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2023 | Book

Proceedings of the 2022 International Conference on Green Building, Civil Engineering and Smart City

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About this book

This book of the conference proceedings focuses on innovative design, technology and methods in the fields of building, civil engineering and smart city. It contains a large number of detailed design, construction and performance analysis charts, benefited to students, teachers, research scholars and other professionals in related fields. As well, readers will encounter new ideas for realizing more safe, intelligent and economical buildings.

Table of Contents

Frontmatter
Correction to: A Systematic Review of Urban Design and Computer Modelling Methods to Support Smart City Development in a Post-COVID Era
Liu Yang, Michiyo Iwami, Yishan Chen, Mingbo Wu, Koen H. van Dam

Green Building

Frontmatter
Numerical Verification of Offline Hybrid Testing for the Seismic Response of Energy Dissipation Structure

Real-time hybrid testing (RTHT) has been developed rapidly for seismic testing. When energy dissipation structure is tested by RTHT, the damper is usually adopted as physical substructure and the structure is adopted as numerical substructure. In order to minimize the seismic response of energy dissipation structure, many dampers installed at different positions are often necessary. The dynamic response of dampers at different positions is different in seismic action. Therefore, more than one damper needs to be tested physically in RTHT, and multiple dampers loaded by multiple actuators in real time will increase control difficulty. To solve this issue, an offline hybrid testing method for energy dissipation structure is proposed based on machine learning, which avoids the challenge of control and stability caused by real-time loading of multiple actuators in RTHT. The feasibility of this method is proved by numerical simulation, which provides a new idea for seismic testing of energy dissipation structure.

Haodong Liu, Zhenyun Tang, Fukang Gao
State-of-the-Art of BRBs in Reinforced Concrete Structures: BRB Units, Connections, Seismic Design, and Performance Evaluation

Owing to the stable hysteresis behavior and favorable costs, the buckling-restrained brace (BRB) is a high-performance damper in seismic areas to protect the building structures from severe damage, especially for steel frames. However, the combination of BRBs and reinforced concrete (RC) structures is complicated, due to the material difference between BRBs and the RC. This study briefly offers state-of-the-art views on the key issues of the combination of BRBs in RC frames (RCFs), such as BRB units, BRB-to-frame connections, seismic design approaches, and performance evaluation procedures. Despite excellent seismic behaviors can be ensured in many BRBs and gusset plates, more high-resilience components require further research. The BBR-to-frame interaction behavior, story shear force distribution relationship, strength and stiffness requirement, and BRB fatigue damage should be taken into account in the design of BRB-RCF systems. This paper aims to provide some recommendations for the development and future prospects of BRBs in RCFs.

Huiming Chen, Jiulin Bai
Design Strategies for Green Retrofitting of a University Student Dormitory in the Hot-humid and Less-windy Climate

Green retrofitting of old buildings is an effective approach for the sustainable urban development. It is different from new green building design and lays much emphasis on the locality and adaptability including climate, function and technology. This study uses a case study approach to demonstrate how to conduct green retrofitting of an old university student dormitory building in a southern city of China, Nanning. The target dormitory building was investigated through field measurement and improvement strategies were proposed based on the investigated results. The improvement effects of the proposed strategies were also quantitatively analyzed using numerical simulation. As a result, it was found that wind speeds around the dormitory are increased by about 0.4 m/s; the average noise level is reduced by about 6 dB; the average outdoor air temperature is lowered by about 5 °C; the daylighting hours inside the dormitory are up by above 1 h; the standard-reaching rate of daylighting is improved from 58.34% to 79.64% and the energy saving rate of building air-conditioning load is raised up by about 0.6%. The findings described in this paper can provide design guidance for green retrofitting of university student dormitories in the hot-humid and less-windy climate.

Binhua Li, Xuexiu Zhao, Yanwen Luo
Analysis of Urban Dual-Carbon Targets and Countermeasures Based on GeoSOS-FLUS Simulation–A Case of Hangzhou City, Zhejiang Province

Revealing the evolution characteristics of land-use carbon emissions in urban areas is helpful to understand the relationship between human activities, urbanization and their influencing factors. It can also provide a scientific basis for the current national land spatial planning and realizing the “dual carbon” goal. Based on the land use data and carbon emission driver data in 2010, 2015, and 2020, this study uses the GeoSOS-FLUS model to simulate the land use situation in 2030, aiming to pass the carbon emission standards and land-use types of different land-use types. The carbon emission in the conversion process is estimated to be the characteristics of Hangzhou’s carbon emission zoning in 2030, and the future carbon governance methods are discussed. After the Kappa and FoM value test, the simulation accuracy of the land use prediction system reaches 95.547%, and the reliability is high. The results show that (1) Hangzhou’s carbon emissions in 2030 will show an upward trend, and the estimated carbon emissions will reach 9706352.272t. (2) The spatial difference of carbon emissions in Hangzhou in 2030 is quite significant. Among them, the carbon footprint pressure index and carbon emission risk index of Binjiang District are the highest, 3082.21 and 27427.467 tons per square kilometre, respectively. The study results can provide evidence that Hangzhou needs to take measures such as establishing a carbon trading market, constructing a carbon monitoring system, and controlling the direction of urban development to achieve carbon governance.

Weiwu Wang, Huan Chen, Shiyuan Cao, Biyan Wang
Research on Macao Cultural Heritage Protection and Sustainable Development——A Case Study of Ruins of St. Paul’s

From the perspective of cultural heritage protection and sustainable development, the paper combines the conference’s concerns on cultural heritage protection, effective development and environmental improvement to ensure the survival, inheritance and development of heritage and make heritage a truly sustainable social activity. Cultural heritage landscape is a renewal model of urban space, which can form a transition space from cultural landscape to modern urban landscape. The information dissemination, spatial renewal and unique culture brought by cultural heritage landscape help to enrich the use function of urban historical and cultural space, and ultimately promote the conservation and development of cultural heritage and tourism development. Ruins of St. Paul’s is one of Macao’s most iconic tourist attractions. The paper takes Ruins of St. Paul’s as a carrier for research, analyzes the landscape status and restrictive factors in the region, and puts forward the landscape control and landscape reconstruction strategy of Ruins of St. Paul’s, which further drives the protection and sustainable development of Macao’s cultural heritage.

Yishan Mao, Yao Wu, Yonglan Wu
3D Printing of Fast Setting Basalt Fiber Reinforced Cement-Based Materials

In this study, the traditional 3D printing process was enhanced, the mixing and pumping processes were removed, and the concrete 3D printer with simultaneous mixing and extrusion of materials was independently developed. The printing of rapid-setting cement-based materials was successfully realized, and the printing performance of rapid-setting basalt fiber reinforced cement-based materials were tested. The results show that the mixing-extrusion integrated concrete 3D printer can successfully print the rapid solidification cement-based composite material with the final setting time of less than 5 min. Under the requirements of printing performance, the dosage range of basalt fiber is 0–2.0%, and the printing performance is the best when the dosage is 1.5%.

Weihong Li, Xuhao Chen, Nan Li
Using Nighttime Light Data to Achieve Precise Estimation of Residents’ Living Carbon Emissions and Landscape Pattern Characteristics

A method for estimating residents’ living carbon emissions and analyzing the spatiotemporal changes of carbon emissions landscape patterns using multi-source data at the township or street scale is proposed. After overlaying the registration of nighttime light data with the registration of Hangzhou township and street-level administrative divisions, the distribution of carbon emissions and carbon emission intensity divisions of the township or street residents in Hangzhou were obtained. Fragstats software was used to analyze the landscape pattern characteristics of living carbon emissions of residents in townships and streets in Hangzhou in 2010, 2015, 2020. The results show that: (1) There is a high Power-law correlation between the living carbon emissions of the township or street residents in Hangzhou and the population distribution, showing a three-layer circle structure. (2) High-intensity areas are concentrated in the northeastern part of the main urban area of Hangzhou, and continue to expand to the northeast, showing the transfer of low-value carbon emission intensity areas and the transfer of high-value carbon emission intensity areas. (3) The landscape pattern of carbon emission intensity has gradually shifted from single-patch control to multi-patch control, among which low-value carbon emission intensity landscape types still play a significant role in controlling urban areas, accounting for more than 70%, and the degree of fragmentation is increasing year by year.

Huan Chen, Biyan Wang, Weiwu Wang, Shan Wang
Research on the Kang in Cold Rural Area Based on Spatial Adaptation and Technological Improvement

Low technology, low cost, high thermal efficiency and other characteristics make cold rural inhabitants reluctant to give up the Kang heating method. The unique Kang technology in some cases has been research hotspots, however how to improve the Kang technology and adapt to the contemporary life is meaningful. Through the on-site investigation and questionnaire survey, it is found that the modern spatial feature is the key constraint of the Kang technology improvement. This paper developed an inheritance pattern of Kang integrated both spatial adaptation and heating effect into account. The numerical simulation was used to prove the heated kang compatible with the modern rural lifestyle, where two conditions were examined:1)the temperature of the main room was increased by 6% and the temperature fluctuation was reduced, 2)the temperature of the secondary room was rised by 14%, achieving better thermal efficiency.

Yiming Li, Hongpeng Xu, Zirui Fang, Chengyuan Bao, Jianmei Wu
Constructing the Mode and Model of Spatial Appeal, Spatial Response for Conservation and Utilization of Chen Hongmou Xiangguo Mansion Site in Qing Dynasty of China Based on Value Evaluation

In this paper, the status of Chen Hongmou’s Xiangguo Mansion Site has been found out basically by Linear space survey, and the Value Evaluation Index System of the Site has been established, through comparing the Site with the Value Evaluation System of Great Site established by Hongwei Liu, then adjusting and supplementing. After evaluating the Site’s value conclusions are drawn as follows: 1) There has a high value of noumenon and environment and it can provide the basis to declare key cultural relics protection units for Xiangguo Mansion Site. 2) There exist three kinds of demands including whole space protection, ontological space protection, and dynamic space change. 3) The thesis formulates three aspects of the response method which include “protection plus overall subarea”, “protection plus ontological perfection” and “protection plus dynamic adaptation”. 4) According to the summary of Visual experience, a height control model is constructed to control the building height by zone. The research results have a good guiding effect on the scientific, reasonable and orderly protection and utilization of the Xiangguo Mansion sites, and provide a mode and model for the protection and utilization of the mansion sites in the Qing Dynasty in Lingnan area of China, and can also provide a reference mode and model for the study of similar mansion protection and utilization in China and abroad.

Zhengmin Wen, Rongsong Quan, Hui Wang, Bing Li, Zhenqiang Li
Air Distribution Analysis and Optimization Layout of In-Row Air Conditioning in Data Center

In order to study the energy-saving and consumption reduction of the data center, taking a practical engineering data center as the object, the physical model of the machine room is established by simulation software, and the airflow organization in the data room is simulated. It is found that there are serious airflow mixing and local hot issues in the machine room. Through the simulation of two kinds of air supply forms of the closed cold aisle and closed hot aisle, the temperature field, airflow field, SHI, and RTI thermal environment evaluation indexes at different heights are compared and analyzed. It is found that the closed hot aisle has better airflow uniformity and temperature stability than the traditional closed cold aisle. At the same time, It is proposed to change the airflow organization of in-row air conditioning from the front supply and the rear return to the side supply and the rear return. The research shows that the airflow organization of the side supply and the rear return has better cooling effects. Through further research, it is found that the air distribution optimization effect is the best when the air conditioning body is pulled out by 30%.

Jianqiang Xu, Zhen Liang
Intelligent Protection and Inheritance Method of the Historic Centre of Macao Based on BIM+ Concept —— A Case Study of Mandarin’s House

The intervention of new technology in the protection of cultural heritage has become the consensus and common goal of heritage protection in all countries. Mandarin’s House is one of the trials conducted by the cultural Bureau of Macau Special Administrative Region in the intelligent protection and utilization of cultural heritage and has made some progress. However, in the process of field investigation and literature research, it can be found that there are still some problems in its protection and utilization. These problems are not only reflected in the protection and utilization of Mandarin’s House, but also in the process of protection and reuse of other cultural heritage in The Historic Centre of Macao. Therefore, this study takes Mandarin’s House as the main research object, explores the problems it is facing at the present stage through field research, case analysis and literature survey, and proposes a solution strategy for intelligent protection and inheritance based on BIM, combined with 3D GIS, Extended Reality, Internet of Things and other technologies. For reference to Cultural heritage protection in Mandarin’s House and other Historic Centre of Macao.

Yao Wu, Hui Zhu
Recycled Concrete Powder Supported Nano-TiO2 Composites: Efficient Utilization of RCP and Excellent Photocatalytic Performance

In this paper, in order to promote the application of recycled concrete powder (RCP), RCP was used to synthesize RCP/TiO2 composites of high value. The microstructure of RCP/TiO2 composites were investigated in detail, and photocatalytic degradation of RhB under UV-light was carried out to assess the photocatalytic performance of RCP/TiO2 composites. The result showed that nano-TiO2 was evenly dispersed on the surface of RCP and firmly combined with RCP by chemical bonds. The RCP/TiO2 composite with only 40% addition of TiO2 exhibited the same photocatalytic performance as equal mass of pure TiO2 within 60 min. There was a threshold RhB concentration for per RCP/TiO2 composite under which an excellent photocatalytic performance can be achieved. RCP/TiO2 composites showed high stability in cyclic tests. The added value of RCP is enhanced by the form of RCP/TiO2 composites. Our work provides a feasible way to promote the upcycling of RCP by preparing value-added products.

Gang Liao, Wu Yao
A Survey on Life Cycle Sustainability Assessment for Triple Bottom Line of Buildings

The idea of life cycle sustainability assessment (LCSA) has recently been embraced in the building field, and academics and practitioners are paying more attention to it. However, the applications of LCSA for triple bottom line (TBL) are still not clear. Therefore, this survey tries to close this research problem by reviewing the peer-reviewed literature papers involved. After illustrating the definition and component of LCSA and TBL, 20 academic publications obtained from the Scopus database were chosen for further analysis and discussion. By summarizing these studies, economic, environmental, social indicators for LCSA are presented. Then, a methodological framework for LCSA consists of four steps: 1) system boundary definition; 2) inventory; 3) impact assessment; 4) interpretation. Finally, the implementations of building information modelling, artificial intelligence, and internet of things will be future directions. Findings from this review are thought to be valuable for academics and practitioners.

Kun Lu, Xueyuan Deng, Baoquan Cheng
Spatial and Temporal Prediction of Carbon Peaking Goals and Zonal Governance Approaches to Achieve Carbon neutrality—A Case Study from Zhejiang Province, China

With global warming, the United Nations General Assembly once again emphasized the control of greenhouse gas emissions. In the General Assembly, China proposed the ambitious goal of achieving carbon peaking by 2030 and carbon neutrality by 2060. In order to study the potential and policy direction of Zhejiang Province in achieving the goal of carbon neutrality, based on the STIRPAT model and combined with ridge regression analysis, two models were constructed to predict the carbon emissions of Zhejiang Province by using scenario analysis. The time to carbon peak was determined by numerical calculation. According to the spatial differences of carbon emission driving factors of low-level cities in Zhejiang Province, the timetable and roadmap for achieving the “dual carbon” goal in Zhejiang Province are put forward. This study also explored the establishment of a regional governance mechanism for carbon peaks in Zhejiang Province. According to carbon peaks’ spatial differential distribution characteristics, a differential low-carbon optimization strategy for land space is proposed.

Weiwu Wang, Huan Chen, Ronglu Yang, Biyan Wang, Yuxin Yang
Peak Projections and Solutions for Carbon Neutrality and Carbon Peaking in the Construction Industry

China’s carbon emissions from buildings account for about 20% of the total emissions during operation. We analyze and point out the main factors that affect the carbon emission in the operation stage of construction industry. On this basis, the long-term prediction model of carbon emission from building operation based on LEAP model is constructed, and the contribution rate of different industries to dual-carbon enterprises is analyzed. The results show that under the current development model, China will not be able to peak its carbon emissions by 2030. Only a combination of control measures, such as electrification of heating systems and efficiency improvements, will ensure that China's carbon emissions peak at 2.7 billion tons in 2030. Between 600 and 800 million tons of carbon need to be neutralized by 2060.

Baoxi Zhang, Zhiqiang Kang, Tongxin Jin
Synthesis and Application of Tackifying Resin in Silane Modified Polyether Adhesive for Prefabricated Building

An branched polyether epoxy resin called FBEPO was synthesized by the ethoxylated pentaerythritol and epichlorohydrin. It can be added to the silane modified polyether sealant (SMP adhesive) as a tackifier. The effects of tackifier (FBEPO) which added to the SMP adhesive on the tack-free time, tensile strength, elongation at break, elastic recovery were studied. Research shown the effect of the bonding between SMP adhesive prepared by only adding FBEPO or aminosilane coupling agent and the precast concrete board (PC board) was general, but adding aminosilane coupling agent and FBEPO at the same time to the SMP adhesive could significantly improve the mechanical properties, elastic recovery rate and adhesion of SMP adhesive. The effect is the best when the amount of aminosilane is 0.5% (w/w) and the amount of FBEPO is 1–2% (w/w).

Yangqing Chen, Yuliang Qi, Hengchao Huang, Jianjun Chen, Keke Huang
Analysis on the Regeneration Strategy of Shikumen Residential Building

Shikumen Lanes are the most memorable and unique residential building for the old citizens in Shanghai. With the changes of the times, which will gradually fade away, and a large number of Shikumen Lanes have been demolished due to the rebuilding, and thence the protection of old buildings have been paid more attention and explored by scholars. In this article, taking the reconstruction project of Shikumen residential building in Shanghai Huaanfang as an example, a meaningful discussion on the extraction and rebuilding of traditional buildings is presented.

Ranran Sun
Research on the Transformation and Development of Modern Western-Style Villas in Suzhou Under the Concept of Sustainable Development

Architectural heritage carries history, accumulated culture and inherited spirit, and its protection has attracted more and more attention. Effective architectural heritage conservation and restoration measures are not only sustainable development of cultural relics, but also play an important role in the sustainable development of social civilization. This paper extracts the natural and social environment that affect the development of modern architecture in Suzhou, then selects the modern Western-style villas in Suzhou as the breakthrough point, summarizing the transformation process of its construction concept, Green construction technology and materials from the aspects of morphological layout, structural technology and residential culture, which could provide basic theoretical support for its repair and protection. Finally, based on the sustainable development strategy, outlooks on ecological methods of heritage protection are promoted, which may contribute to the inheritance and innovation of modern western-style villas in Suzhou, So as to promote the sustainable development of Suzhou, a famous Jiangnan city.

Yonglan Wu, Yao Wu, Yishan Mao
A Multi-objective Optimization Approach of Green Building Performance Based on LGBM and AGE-MOEA

This paper proposes a novel multi-objective optimization approach for green building performance combining Building Information Model (BIM) and artificial intelligence (AI) algorithms. LGBM and AGE-MOEA algorithm are respectively utilized to construct the prediction and optimization model, and finally the multi-objective optimization process for total site energy consumption, CO2 emission and discomfort hours can be achieved by changing values of 12 corresponding level-2 indicators. The pareto front and the optimal solution are obtained. The applicability and effectiveness of the optimization method are verified by a practical case, and the results suggest that: (1) the accuracy of LGBM prediction model is as high as 99.975%; (2) under the multi-objective optimization of AGE-MOEA algorithm, the green performance metrics of building information model has improved by 14.32%, which is better than that of widely used NSGA-II and NSGA-III algorithms under the same conditions; (3) the setting of HAVC system is the biggest factor affecting the performance of green buildings.

Yuxuan Shen, Yue Pan
Carbon Emissions of Passive Building During Production and Operation in Cold Region of China

Passive buildings have long been regarded as energy-efficient and environmentally friendly buildings. This kind of buildings can reduce the heat loss of the building by improving the thermal resistance of building envelope and improving the air tightness of the buildings. In this paper, carbon emissions of passive buildings in cold regions and traditional building models based on the example of passive building in the same geographical conditions were calculated and analyzed in the production section and operation section of the building. This article analyzes the carbon emission characteristics of passive buildings in the production section and operation section of building materials, which account for the vast majority of carbon emissions in the whole life cycle of passive buildings. According to the case calculations, the carbon emission of the passive building is 0.77t CO2/m2 in the production section of building materials, and 3.07t CO2/m2 in the operation section. Compared with traditional buildings, the carbon emissions of passive buildings is 37.5% higher in the production section of building materials, 53.27% lower in the operation section. The analysis shows that passive buildings have low carbon characteristics compared with traditional buildings in the whole life cycle.

Zhiqiang Kang, Bo He, Xiaodong Xia
Strength of an Improved Connection for Modular Concrete Structures Without Onsite Casting

This paper presents an improved design for connections to be applied in modular concrete structures. The proposed the connection removes the onsite casting procedure, which improves the productivity in the modular construction. The installation of the connection requires only bolt connections between the two adjacent prefabricated units. The current study aims to investigate the structural performance of the connection under ultimate loading conditions through the calibrated finite element analyses. The validation of the finite element analyses employs a reported experimental study in the literature. Based on the parametric investigation, the proposed connection demonstrates satisfactory ultimate strength with sufficient ductility. The parametric study also examines a number of important parameters for the connection.

Chengguang Xu, Xudong Qian, Ran Tao, Rong Wang
Research on Application Effect of Built-In Louver Insulating Glass Window

This article focuses on the built-in louvered insulating glass. This article focuses on the built-in louvered insulating glass, Analyzed heat transfer of the built-in louvered insulating glass window. Through the simulation calculation of the whole summer, when the louver of the built-in louver is pulled downward and the angle of the louver is 90°, in Shanghai, Beijing, from the perspective of the cumulative total heat gain of summer windows, single-layer LOW-E glass > double-layer LOW-E glass > insulating glass + indoor blinds > built-in louvered insulating glass. Through the simulation calculation of winter heating period, it is found that the single-layer Low-E glass is the smallest in different directions in the two areas, while the total heat gain of hollow shutter glass and double-layer Low-E glass is different.

Aofeng Shi, Guoqing Yu
Micro-scale Regional Spatial Low-Carbon Planning System Framework Based on Scenario Analysis

As the development of national space continues to accelerate, the pressure of carbon emission is increasing day by day. It is urgent to consider how to guide the low-carbon development and construction of territorial space scientifically and directly from the planning department. Therefore, this article studies the relative lack of micro-scale of land and space as the research object, trying to build based on the scenario analysis method, index constraint method as the core, supporting system and standard as the safeguard of micro-scale space low carbon technology framework, finally realizes “Harmony between man and land for Natural harmony” the overall framework of the target. It is hoped that this study can provide some reference value and inspiration for low-carbon planning at the micro-scale.

Zhexuan Chen, Junting Chen
The Optimization of High-Density Campus Transportation Based on Green Transport

With the increasing importance of the concept of sustainable development and environmental protection, green transportation has become one of the core ideas of modern transportation planning, but it is mainly applied to urban transportation rather than campus transportation. The travel characteristics of campus transportation are different from those of urban transportation, and high-density campuses with higher population density and building density are more in need of green transportation methods. The article takes the Xinzhuang campus of Nanjing Forestry University as an example, and investigates the campus in three aspects: spatial form, dynamic traffic and static traffic; by drawing on the neighborhood community model, emphasizing the status of slow traffic and adopting green technology, it proposes optimization methods such as dividing campus clusters, creating campus public space, optimizing road classification and cross-sectional form, supplementing public transport and compounding the layout of parking facilities to alleviate the paradox of traditional campus transport. The aim is to provide a healthy and safe travel environment for students and teachers, and to provide a reference for other high-density campuses in terms of traffic optimization.

Ming Liu
Design of Wave Energy Capture Structure and Research on Mooring System

The wave energy in the ocean contains huge energy and how to convert its unstable energy into stable energy with sustainable output is a significant problem to be solved. In this study, a truss-type trilateral wave energy capture device is designed and modeled. More importantly, the influence of different mooring systems on the device is clarified. The results show that the six mooring line system can effectively improve the anti-wave performance and vibration reduction capability of the wave energy capture device, and reduce the surge response displacement of the device by about 37% under regular waves.

Mingjun Li, Xinhui Duan, Zheng Huang, Yan Wei
The Concept and Strategy of Territorial Spatial Planning System for Construction Waste Reduction and Resource Utilization

This study intends to combine the content and methods of current construction waste resourceful disposal technology, and connect the work of construction waste reduction and resourceful utilization with the territorial spatial planning system. In the process of management, preparation, implementation and supervision and inspection of territorial spatial planning, the objectives, processes and requirements of construction waste reduction and resource utilization are formulated in terms of laws and regulations, norms and standards, overall territorial spatial planning, special planning, zoning planning, control plan preparation, urban design, construction approval, planning verification and legal responsibility, and implemented in planning texts, control plans, planning design conditions, urban design guidelines and In the chart of construction waste reduction and resourcefulness, the construction waste reduction and resourcefulness is implemented into the spatial planning and source management. Through scientific and reasonable planning, the work of construction waste reduction and resource utilization is unified into the spatial planning system of the country, which is more conducive to making guidance from the top, controlling and prejudging construction waste from the source, reducing waste of resources, lowering transportation costs, protecting the construction environment, realizing the source reduction of construction waste and lowering disposal costs, changing passive end management into active source research and recycling, and fundamentally solving the problem of construction waste reduction and resource utilization.

Shuaibo Li, Yingying Zhou
The Study on the Development of Contemporary International Timber Heritage Conservation

Wood built heritage has always been the focus of international heritage conservation because of its special material properties and rich geographical and cultural characteristics. Taking the 2017 revision of the International Council on Monuments and Sites (ICMONUMENTS) Code for The Protection of Wooden Built Heritage and the main content of IIWC conferences in past years as the research object, this paper analyzes the changes in the Code and explains the deep-seated reasons for the changes. It also explains the response and adjustment of the international conservation community to the conservation concept, method, technology and management of wooden heritage in the past 20 years. The paper then looks forward to the development trend of international wooden built heritage protection since 2018 and compares the programmatic documents in China to propose mutual reference areas.

Xi Chen, Mei Huang
Analytical Evaluation for Optimization of Landside Traffic System Planning at a Hub Airport

With the explosive growth of airport passenger and cargo traffic, the operational efficiency of airport ground transportation affects the overall development of the airport. It is important to correctly understand the operation of airport ground transportation networks, evaluate key road nodes, and identify bottlenecks in transportation development for the sustainable development of airport ground transportation in the future. This study takes the land traffic of a hub airport in China as the research object and conducts a simulation analysis of the land traffic of this airport. The operational performance of the landside traffic is discussed by analyzing the simulation results using VISSIM traffic simulation. Potential problems, such as traffic congestion at the entrance and exit of the parking lot, are identified. Suggestions for improvements are also given in this paper.

Hongjing Ge, Jiang He
Study on the Protection and Development of Farming-Type Traditional Village Landscape Under the Concept of Sustainability – A Case Study of Western Henan

For traditional village landscapes, sustainability can be seen as a complex system consisting of four dimensions: environmental, social, economic, and cultural. Based on the concept of sustainability, this paper takes farming-type traditional villages in western Henan as an example. By evaluating resource characteristics and distribution, conservation, and utilization of 11 typical traditional village samples, we summarize the resource characteristics of the villages and the sustainability and shortcomings of the existing development model. At the same time, through integrating the survey results, we propose strategies for the renewal of western Henan farming-type village landscapes in three aspects: environmental sustainability, economic and social sustainability, and cultural sustainability.

Sai Yin
Surrogate Based Multi-objective Optimization for Energy-Saving Building Design

In order to coordinate building energy consumption and indoor comfort for architectural design, a surrogate based multi-objective optimization approach is proposed in this paper. Taking a rectangular planar layout of civil housing as an example, several design parameters closely related to building energy consumption and indoor comfort are selected. With the help of EnergyPlus energy consumption simulation analysis software, the sample data can be generated by simulating the software. Thus, a three-layer radial basis function (RBF) neural network is used to train and learn the sample data, and the models of building energy consumption and indoor comfort can be established. The established energy consumption and comfort models are verified by the experiments. On this basis, NSGA-II multi-objective optimization algorithm is used to balance the building energy consumption and indoor comfort to obtain the value range of design parameters and the Pareto front. So, the optimization results can be used to guide energy saving architectural design.

Yuchen Chen, Xuhua Shi
Research on the Development of Modern Mosaic Wall Decoration Materials Based on Nostalgic Memory—Taking Wumi Congee (Congee Shop) in Cantonese Area of China as an Example

Mosaic is an ancient method of building wall decoration. Based on the memory of nostalgia, this paper develops and designs the decorative materials for the walls of the Wumi Congee (Congee shop), which was designed from the renovation of the village house in the Cantonese Area of Lingnan, China. By introducing in detail the design and development process of the red series ceramic mosaics in the restaurant, the modular combination method of ceramic mosaics, the material properties and the experience of innovative design practices, it provides a reference for the subsequent building wall material decoration.

Qiang Tang, Yile Chen, Junzhang Chen, Liang Zheng
Exploration and Practice of the Application of Natural Lighting and Shading Technology in Building Energy Conservation

Natural lighting and shading technology, as an important factor in building energy conservation, has attracted much attention in building design and renovation in recent years. Taking the renovation design of a college building in Taizhou as an example, this paper focuses on analyzing the design methods and influencing factors of building natural lighting and shading technology, and analyzes the renovation objectives, design methods and performance comparison before and after the renovation, Emphasize the importance of natural lighting and shading technology, and the appropriate renovation strategy and design concept are given. so as to provide relevant reference for the application of building lighting and shading technology. It also provides experience for building sustainable development in the future.

Jinghua Shen, Jie Zhang, Zhaoyang Xue, Jie Wu
Analysis of the Effect of Stress Intensity Factors on Temperature-Shrinkage Reflective Cracks

A 6-parameter generalized Maxwell model is established considering the viscoelasticity of the asphalt mixture, using the second phase of the reconstruction of the East Ring Road of the existing motorway in Nanning, Guangxi as the engineering background. ABAQUS software is used to analyse the changes in stress intensity factor at the tip of temperature-shrinkage reflective cracks under the changes in initial temperature, temperature drop range, temperature drop rate, pavement structure layer, interlayer contact state and crack length. The results show that the stress intensity factor for the same relaxation time gradually decreases as the initial temperature increases, and the relaxation curve gradually slows down; the stress intensity factor for the same relaxation time gradually increases with the increase of the cooling rate of the road surface, and the relaxation curve gradually slows down; there is a positive correlation between the length of the reflective cracks and the stress intensity factor under the same relaxation time condition; there is a positive correlation between the stress intensity factor, the cooling rate of the road surface and the length of the reflective cracks under the same relaxation time condition.

Qinshou Huang
Exploration of the Emergency Renovation of Sports Venues Resilience Space Based on Green Building Technology Under the Normal Epidemic Situation

The sudden outbreak of COVID-19 has caused a surge in medical demand. It has inspired people to continuously explore how to transform public buildings such as gymnasiums in a fast, low-cost and green way during emergencies. The article studies the feasibility of applying gymnasium to sudden public events, discusses the design methods for the renovation of gymnasium space, water supply and drainage system, ventilation system and intelligent system in emergency situations. The focus is on preventing cross-contamination, preventing backflow contamination, pressure shaving, airflow organization, and system control. Through these design methods, the gymnasium has the characteristics of efficient, adaptable and inclusive epidemic prevention. The application prospect of green building technology in emergency reconstruction was explored, and a reference is put forward for the design and reconstruction of gymnasiums in the post-epidemic era with “combination of epidemic control” and improving the resilience space of gymnasiums.

Jie Liu, Tong Yang
Research on Boundary Space Design of Urban Residential Community in the Pearl River Delta

The essence of boundary space is the transition and fusion zone of two different substances, space or regions. As a form of living closely related to people’s life, the way of presentation of public space affects people’s every move. The author hopes that through the research of urban residential community boundary space types in Pearl River Delta region, taking different types of common problems as the starting point, from the perspective of urban protection and renewal, through “architectural design”, “art design”, “landscape aesthetics” etc. explore the new model of harmonious coexistence and greening between people and nature. This is not only the transformation and continuation of the ecological environment, spatial environment, cultural environment, visual environment, and recreation environment, but also the continuation and renewal of the social network structure, psychological setting, and emotional attachment of the neighbors.

Junrui Cao, Yichenfei Guo
Distributed Ledger for Construction Material Providers to Control Carbon Emissions, a Case Study of Glulam Material

To combat global warming, the European Union pioneered an emissions trading system (ETS) that regulates emissions in government-selected industries and has proven to be successful. In many countries, the construction industry is enforced to join the ETS because of its high energy consumption and emissions. Nonetheless, most existing ETSs only cover the operation phase of a typical project while the materialization phase is rarely considered. The materialization phase includes emission from both construction work and the construction material production. Currently, there are few instruments to evaluate carbon emission within the manufacturing process of construction materials. As the accurate data is not available, the benefits of low-carbon construction materials such as the glulam are veiled to the public. To address such issues, this paper proposes a carbon emission assessment tool for wood products such as glulam during the production stage. The new tool is also supported by the distributed ledger which is highly compatible with future ETSs under Industry 4.0 framework. The system enables construction material manufacturers to evaluate, upload, and share information in a distributed manner. Carbon emissions and materials properties simultaneously updated on the chain when producing constructional materials. Such a system serves as a foundation of subsequent construction material and carbon allowance trading.

Wenhao Liu, Zhan Shu
Dynamic Response Analysis of Stress Intensity Factor of Reflective Cracking in Asphalt Pavement Addition

Taking the second phase of the reconstruction of the East Ring Road of the existing motorway in Nanning, Guangxi as an example, this paper employs ABAQUS software based on kinetic theory and the plane strain finite unit method to analyse the dynamic stress intensity factor variation law with time under dynamic load for reflection cracks. The results show that: the time course curve of dynamic stress intensity factor slows down as the thickness or modulus of asphalt paving layer increases; the time course curve slows down as the thickness or modulus of stress absorbing layer increases; the amplitude gradually becomes smaller as the vehicle speed increases; the amplitude gradually becomes larger as the axle load increases; the vibration curve gradually tends to level off as the action time continues, and the time course curve does not completely decay to zero when the load action ends.

Qinshou Huang
Study on the Evaluation Index System of Reinforcement and Renovation of Existing Campus Buildings: Take Yueyi Building as an Example

In the context of the constant perfection of the green building system,a substantial proportion of old campus buildings need to be reinforced and renovated to meet the requirements of safety, use, energy saving and so on. However, due to the unique characteristics of the existing campus buildings in terms of cultural inheritance, functional improvement, and usage and so on, the existing index system of reinforcement and renovation cannot fully and purposefully evaluate the reinforcement and renovation of campus buildings. Taking Yueyi building of Soochow University as the object of practical measurement, studying the green building concept, analyzing the relevant evaluation index system of buildings with a comprehensive subjective and objective evaluation method and searching for the correlation between the renovation of ultra-low energy consumption buildings and the building reinforcement project, the study aims to build a scientific and reasonable evaluation index system for existing campus buildings. Lastly, an overall evaluation index system with two levels of reinforcement and renovation is built to provide a reference for the selection of reinforcement and renovation plans and to guarantee the sustainable development of existing campus buildings.

Xiaoxue Tang, Jie Wu, Youqing Zhu, Ruijie Xu, Shunuo Li, Qianqian Yan
In-Process Reinforcement Method for 3D Concrete Printing: Status, Potentials and Challenges

3D concrete printing (3DCP) as a revolutionary technology has reached the construction industry with numerous achievements. While the key to promote the structural application of 3D printing lie in the effective reinforcement approaches that ensure the mechanical capacities of printed structures. Many researchers have tried to find solutions to reinforce 3D concrete printing elements. Hence, the need to review the different types of in-process reinforcement solutions based on their mechanical performances, their application process challenges, and their performance on different structures. Our primary focus is to examine ten different reinforcement solutions used in 3D concrete printing over the past ten years. This paper shows the improvement of each reinforcement strategy over time and propose a reinforcement solution that can be considered for future research.

Billy Kazadi, Liang Yao, Li Wang
Systematic Framework of Economic KPIs for Prefabricated Building Construction

Prefabricated construction has been increasingly adopted in building projects all over the world because prefabrication technology has tremendous advantages over the cast-in-situ construction. However, the development of prefabrication technology in China has encountered many challenges such as cost overrun. Economic performance determines the success of a project, which has raised the attention of construction project stakeholders. Therefore, this study aims to develop a systematic framework of economic key performance indicators (KPIs) for measuring prefabricated buildings. First, this paper establishes a systematic framework of eight KPIs through a comprehensive literature review. The KPIs cover unit cost, cost variance, etc. Second, to demonstrate the use of the framework, a cross-case study is conducted to measure and compare the economic performance of a prefabricated building and a building built using cast-in-situ construction. Throughout the case analysis, the economic performance of a building project using prefabricated construction is much better than that using cast-in-situ construction. For example, the overall delivery of prefabricated buildings is 30%–50% faster than that of traditional buildings. The paper should assist construction enterprises in measuring the economic performance of prefabricated building projects and could also facilitate the development of prefabricated construction in China.

Bingyan Wang

Civil Engineering

Frontmatter
Numerical Simulation of Resists Progressive Collapse of the Elevated Station

To study the progressive collapse resistance of the elevated station, LS-DYNA software was used to establish the pure frame numerical simulation model for the elevated station in Xi’an Station, and 1–3 columns in the corner area and in the middle area were removed for numerical simulation analysis. The results show that the elevated station has good robustness. Under the conditions of single column removal and double columns removal in the middle area, the beam mechanism is the main resistance mechanism, and the catenary mechanism is developed under the three columns removal condition. Finally, the influence of the floor on the collapse resistance of the high-speed railway station was analyzed, and the results show that the deformation of the structure can be effectively reduced, and the collapse resistance of the structure can be improved by the tensile membrane mechanism of the floor under the large deformation of the two columns and three columns removal.

Xiaolan Yuan, Weizhuo Huang, Guangtao Li, Zhi Li, Xiaofang Deng
Numerical Simulation Method of Dynamic Coupling of Complicated Mountains and the Wake of Multiple Wind Turbines

The computational fluid dynamics (CFD) method is widely employed in the numerical simulation of wind turbine wake with the advancement and improvement of computer technology. In the simulation of wind turbine wake, the actuator disk model (ADM) has been verified. This method, however, can only isolate the wake flow field of a single wind turbine and does not take into account the mutual coupling effect between numerous wind turbines’ wakes. As a result, this paper proposes a calculation method that takes into account the dynamic coupling of multiple wind turbines’ wakes, and explores the coupling effect between the wakes of multiple wind turbines and the terrain by dynamically updating the resistance source term in real time according to the incoming wind speed during numerical simulation. The revised dynamic updating source term approach can detect the incoming wind speed on the basis of ensuring the quality of numerical simulation, making it more suited for linking numerical modeling of complex terrain flow field and the wake of many wind turbines.

Chi Ma, Shuanglong Fan, Zhenqing Liu
Numerical Simulation of Substructure Shake Table Testing for Base-Isolated Structure Using Model-Based Integration Algorithm

Base isolation is an effective method of reducing the seismic responses of structures. As a promising experimental measure, substructure shake table testing (SSTT) can be used to investigate the seismic performance of base-isolated structures. Model-based integration algorithms have the advantages of explicit formulation and unconditional stability, and thus they are very suitable for SSTT. In this study, the SSTT using a family of generalized CR (GCR) algorithms for the base-isolated structures is numerically studied. Firstly, time history analyses of a six-story base-isolated structure are conducted and compared with the corresponding non-isolated structure. Then, the SSTT approach using the GCR algorithms is proposed for the base-isolated structures. The numerical simulation of a series of SSTTs with different time steps, integration coefficients and time lags are finally conducted. The results indicate that the GCR algorithms with relative large time step still have excellent accuracy. The SSTT results of using the subfamily of κ1 = 1 are less accurate than the subfamily of κ1 = 1/2. In addition, the time lag has obvious adverse effect on the SSTT results. There is an instable tendency of the SSTT results as the time lag increases.

Bo Fu, Futai Zhang, Jin Chen
Effect of Ceramic Waste Powder on Mechanical Properties of Recycled Coarse Aggregate Concrete

In this paper, the recycled coarse aggregate concrete (RCAC) was prepared by replacing cement with ceramic waste powder (CWP) in mass fractions of 0, 10%, 20%, 30% and 40%. Its mechanical properties, hydration products, microstructure, and morphology were investigated by means of isothermal calorimetry, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and universal testing machine. The results show that the early compressive strength of RCAC is reduced by the addition of CWP, but the compressive strength of RCAC with 10% and 20% CWP increased by 12.53% and 4.78% respectively. In addition, after 56d of curing, the splitting tensile strength and flexural strength of RCAC with 10% CWP are higher than that with none CWP, but lower than natural aggregate concrete (NAC). The incorporation of CWP would accelerate the hydration of blended paste slightly, which leads to earlier exothermic peak. On the other hand, CWP could markedly reduce the total hydration heat and the hydration exothermic rate. The TG results showed that the content of Ca(OH)2 in CWP-cement paste decreased with the increase of CWP content after 56d of curing. It can be seen from SEM that the incorporation of CWP makes the microstructure of hardened paste more compact.

Ronghui Yang, Xin Min, Feixiang Chen, Gang Li
Construction Technology Innovation of Light-Weight Steel-Concrete Composite Cable-Stayed Bridge

Jiangxinzhou Yangtze River Bridge in Nanjing, built at the end of 2020, is one of the important river channels in Nanjing. The bridge is composed of a central double-cable plane three-pylon Light-weight composite beam cable-stayed bridge with two main spans of 600 m. In view of the new structures such as steel shell concrete pylons and UHPC-steel Light-weight composite beam with coarse aggregate, the innovative construction technologies and equipment such as segmental manufacturing and installing of steel shell concrete pylon, industrial precast UHPC bridge deck with coarse aggregate and integral manufacturing and installing of Light-weight steel-concrete composite beam are systematically developed, which significantly improve the engineering quality and construction efficiency, and promote the great transformation for bridges from field construction to industrialized lean construction.

Xueyun Kang, Qi You, Gang Li, Huijun Shen
Numerical Simulations of the Effects of the Radiant Floor Combined with the Displacement Ventilation of the Spread of Exhaled Contaminants in the Confined Space

The COVID-19 pandemic has seen the importance of confined space ventilation to reduce the risks of cross infection. To evaluate and compare the relative impacts of different mitigation strategies is important in order to reduce the risk of infection in a given situation. Using CFD methods, this study aimed to modulate the spread of exhaled contaminants in a floor-heated and ventilated space. Three different inlet velocities and four floor temperatures were used to assess the effect of the radiant floor combined with the displacement ventilation (RFDV) on room airflow and pollutant spread. Results show that RFDV reduced exposure to infection from 87% to 50% compared to the reference case. The inlet velocity is required to increase when the floor temperature is higher to decrease the contaminant exposure risk to in the room. This research provides a timely and necessary study of the ventilation and heating systems. These findings are expected to be useful for designing future of RFDV.

Jie Wu, Liang Xu, Jing Hua Shen, António Candeias, Wei Zhang
Research on Impact Collapse Resistance of RC Beams After Fire

In order to explore the mechanical properties of improve concrete (RC) beams of the combined action of impact load and fire, numerical simulation of the high temperature test of RC slabs conducted by ZHANG et al. was carried out based on ABAQUS finite element software to verify the effectiveness of sequential thermal-mechanical coupling modeling. Then, numerical simulation of impact tests such as FUJIKAKE was carried out and the influence of temperature deterioration effect was considered, and the influence of different fire duration, drop height of drop weight and beam reinforcement ratio on impact resistance of RC beam after high temperature was studied. Finite element analysis shows that with the fire time, the RC beam changes from bending failure to shear failure, which significantly reduces the impact resistance of RC beam. When the drop height of the drop weight and the beam reinforcement ratio are the same, the maximum impact force of the beam and the maximum reaction force of the support decreased by 21.03% and 24.62%, respectively, compared with the case without fire in the cases of 90 min of fire exposure. Under fire conditions, increase the reinforcement ratio can effectively reduce mid-span displacement, but has limited impact on maximum impact force and the maximum reaction forces of support.

Zhi Li, Kaiqian Huang, Xiaolan Yuan
Method Research on Traffic Volume Forecasting Based on Bio-LSTM

Nowadays, urban traffic management plays an important role to improve traffic system efficiency and ensure safety, and decision-making about that is based on the adequate understanding for traffic condition. Traffic volume is the representation of current traffic operation, so it is of great significance to master traffic volume in advance and accurately. The developments of computer and Deep-Learning provided support for traffic forecasting. Firstly, the principle of Long Short-Term Memory neural network (LSTM) to overcome “gradients vanishment/explosion” is analyzed. And then Bio-LSTM is used to forecast the traffic volume of a certain road in the next 24 h. Finally, the Wavelet Neural Network is used to predict the same data of this road. The two series of prediction results are compared, it is showed that Bio-LSTM for prediction has the advantages of simple operation, convenient adjustment of key parameters and higher prediction accuracy.

Xiao Li, Chaoyang Li, Tao Wang, Yi Zhang, Changqin Xi
Application of BIM in Automatic Typesetting of Universal Segments in Shield Tunnel

Shield method is an advanced construction method of underground engineering, and the typesetting of segments is an important procedure in the construction process. The traditional segment design method is not easy to modify, low efficiency. This study proposes a universal segment automatic typesetting method based on BIM technology. Firstly, a parametric lining ring template is established in the BIM platform according to the segment geometry. A python script was created to realize the secondary development of the BIM platform and then select the appropriate point of the lining ring based on the distance between the center point of the lining ring and the tunnel axis. A shield tunnel project is used to evaluate the automatic segment assembly algorithm. The results show that the proposed algorithm can quickly establish a shield tunnel model, which improves the design efficiency of segment to a certain extent. The method proposed in this paper has certain significance for guiding the design of the segment and the assembly in the construction process.

Liujie Zhu, Yuxian Zhang, Jixun Zhang, Zichang Ma
Rating Techniques Research on Operation Performance of Continuous Box Beam with Common Span in China High Speed Railway

Rating techniques for operation performance of continuous box beam with common span are discussed based on measured data and theoretical research on dynamic performance of bridge in China high speed railway in recent years. Rating tasks are analyzed and the main technical parameters to evaluate the operation performance of continuous box beam are proposed. According to the statistical analysis on measured data of the bridge dynamic performance by the testing and commissioning of high speed railway with the reliability of 97.5%, the suggested ordinary value of main parameters of prestressed concrete continuous box beam under 250 and 350 km/h high speed train operation speed are put forward: the vertical natural frequency is determined by the power function of span, the vertical damping ratio is 0.5% to 2.0%, the ratio of deflection to span is 1/5500 to 1/3500 and 1/6000 to 1/4000 respectively, the vertical rotation angle at girder end is 0.60‰ and 0.50‰ rad respectively, the dynamic factor is 1.17 to 1.26 and 1.20 to 1.30 respectively, the vertical and lateral amplitude at midspan of beam is 0.25 to 0.80 and 0.10 to 0.15 mm respectively, the vertical vibration acceleration at midspan of beam is 0.25 to 0.40 m/s2, the lateral amplitude at pier top is chosen as the ratio of the height of pier and the lateral average width of the pier in the range of 0.5 to 4.2, the relative lateral displacement of rail support on both sides of adjacent girder end of ballastless track is 0.5 mm.

Wei Wang, Penghui Liu, Xin Meng, Zhensheng Dong, Jing Yin, Yigan Wang
Static Simple Shear Tests on Mechanical Behavior of Interface Between Coral Sand and Concrete

There are various concrete foundations and retaining structures on the islands and reefs, which are subjected to various static and dynamic loads. The interaction characteristics of the contact surface between coral sand and concrete is the key to affect the stress and deformation of rock and soil mass and structure. The static simple shear test of the contact surface between coral sand and concrete was carried out using the simple shear tester. The influence of normal stress, different roughness, particle size and relative density on the static shear characteristics of the surface of contact was studied. The relation between axial displacement, shear stress and tangential displacement of interface. The experimental results indicate that the magnitude of the normal stress has a certain effect on the normal displacement and shear stress of the contact surface, and there is a direct proportional relationship between shear strength and applied normal stress.; the roughness of the contact surface is relatively dense with the coral sand The degree also has a positive effect on the shear stress of the contact face; The particle size has a certain influence on the shear stress and normal displacement of the contact surface.

Chunyong Jiang, Xuanming Ding, Gang Yang
Concrete and Steel Structure of High-Rise Modular Buildings: A Systematic Review

Modular construction has been increasingly adopted in high-rise building projects recently and various studies have been carried out on high-rise modular buildings. However, the majority of the previous research focused either on steel-framed modular structures or on concrete modular building. There is still a lack of systematic review on both steel and concrete modular systems for high-rise building development. Therefore, this paper aims to systematically review the research and development on high-rise modular buildings by investigating the state-of the-art practices and academic research to point out the future research directions. A comprehensive and critical literature review is conducted, including over 30 journal papers and 10 case projects all over the world. Content-based analyses is utilized to analyze the identified journal papers and the case projects. Results of the review reveal that the previous research mainly focused on steel modular system; and most of the case projects are low- to mid-rise, while few of them are high-rise buildings. In future, the paper suggests focusing more on innovative structural connection system for both concrete and steel modular buildings. Throughout the systematic review, this paper contributes to both the knowledge and the practices of high-rise modular construction.

Zhen Yu
Dynamic Properties of Hydrophobic Sand as a Filling Material in Road Subgrade

In order to ensure the safety and comfort of vehicle transportation, a great concern has been given on the subgrade of road about its deformation and stability. Water is one of the most important contributing factors to the diseases of subgrade such as frost heave in cold areas and collapse in saline soil subgrades. Addressing water-induced subgrade damage is usually costly and time-consuming. This study proposed a novel solution by using hydrophobic sand as a subgrade filling material. Hydrophobic sand can impede water infiltration with low cost. Although such sand has been proofed to hinder the water movement effectively, its dynamic mechanical properties are still unclear which are important for the assessment of subgrade seismic response. This study tests four hydrophobic sands by resonant column test to investigate the effect of hydrophobized treatment and outdoor weathering on their dynamic properties. Hardin-Drnevich model is used to fit relationship curves of dynamic shear modulus with shear strain. The result showed that hydrophobized treatment increased both dynamic shear modulus and damping ratio, depending on the type of water repellent agent and outdoor weathering duration. Hardin-Drnevich model is applicable for all tested subjects.

Gege Huang, Hongjie Lin
Effects of Redispersible Latex Powder on the Performance of 3D Printing Cementitious Materials

To investigate the effects of redispersible latex powder (RLP) on the workability and mechanical properties of 3D printing cementitious materials (3DPC), the fluidity, extrudability, open time, buildability, green strength, flexural strength, and compressive strength of cement mortar with 0%–4% of RLP were investigated. Results show that RLP can improve the fluidity, buildability, and open time of 3DPC, but it negatively influences the strength of 3DPC. When the dosage of RLP is about 2%–3%, the strength loss of 3DPC is not significant.

Huan Wang, Xinchen Tian, Huixian Wei, Xueyan Dai, Yujun Che, Huashan Yang
Study on the Deterioration Law of Sleeve Grouting Defects on the Lateral Bearing Capacity of Assembled Shear Walls

Sleeve grouting defects in assembled buildings leave a major safety hazard for building safety. Assembled shear walls are the most widely used key lateral force resisting element in assembled buildings and their lateral bearing capacity is critical to the safety of the building. However, the deterioration pattern of the defects on the lateral bearing capacity of assembled shear walls is still unclear, which makes it impossible to make an accurate assessment of the performance of defective assembled shear walls and thus to develop reasonable reinforcement solutions. In order to be able to accurately predict the lateral bearing capacity of defective assembled shear walls. A non-linear finite element model of the defective assembled shear wall structure was developed using the finite element software ABAQUS and compared with tests to verify the correctness of the model. Subsequently, the influence of the defects distribution and the defect rate on the ultimate lateral bearing capacity of shear walls was investigated. The results show that defects concentrated on one side of the wall are more harmful than uniformly dispersed defects, and the degree of deterioration effect of individual defects decreases as the number of defects in the same part increases. Finally, the deterioration coefficient, which reflects the degree of deterioration of defects on the lateral load bearing capacity of shear walls, is obtained, and can be used to calculate the lateral bearing capacity of assembled shear walls with defects, providing a reference basis for the performance assessment of assembled buildings.

Qizhou Liu, Yuhan Lin, Jinzhou Li, Min Zhang
Monitoring Technology of Runway Pavement with Holes Based on Vertical Shear Strain

Analytical solution of flexural-tensile strain and vertical shear strain in slab on elastic foundation were obtained based on theory of moderate thickness slab and the relation between vertical shear strain and flexural-tensile strain on slab bottom was obtained by the solution. The finite element model of slab with holes was built by ABAQUS to analyze the distributing characteristics and influence factors of vertical shear strain in holes under aircraft load. The model test of slab with holes was designed to obtain the vertical shear strain and its distribution characteristics in the holes. The research results show that there is a linear correlation between vertical shear strain and flexural-tensile strain with the same location of aircraft load. The distributing characteristics of vertical shear strains are different in different holes. In addition the results obtained from the model experiment show that distributing characteristics of vertical shear strain in holes are in accord with theory resolution and finite element analysis results. The shear strain in the holes increases with the load’s increasing. Flexural-tensile strains on the slab bottom calculated by vertical shear strain in holes differ from the measured values with maximum value of 16% and this value is conform to the engineering test require, which indicates that the monitoring technology of flexural-tensile strain calculated by shear strain is feasibility and the state of the existing pavement slab can be monitored with this technique.

Jing Cai, Hanxue Wang, Yue Li, Zhiqiang Du
Research on Vibration Control for Transformers of Off-Shore Wind Turbine

Offshore wind power has gradually become the mainstream of wind power generation, which has the characteristics of more resources, less turbulence and far away from human living areas. However, offshore wind turbines bear great wind and wave loadings in complex working environment, and various components are also prone to damage in work. Among them, transformer is an important working component in offshore wind turbine, with complex internal structure and large size. Therefore, it is necessary to study the motion response of transformer in operation. In order to design a larger offshore transformer that can adapt to a more complex environment to configure today’s larger offshore wind turbine and ensure its safety and stability, a damping device can be added to the usual transformer to enhance its anti-vibration ability and reduce its motion response. This paper introduces the modal analysis theory, uses SolidWorks to model the transformer, and uses ANSYS software to calculate and analyze the modal of the transformer before and after setting the vibration damping device and the vibration life at the main frequency. It can be found that the vibration damping device can greatly improve the vibration resistance of offshore wind turbines.

Xianqing Guo, Chengyuan Wang, Hongju Wu
Hybrid Simulation Platform for Onshore Wind Turbine Under Coupled Wind-Earthquake Load

Onshore wind turbines are usually faced the challenges of multiple disasters such as wind and earthquake. With the continuous growing demands on the generating capacity of wind turbine, the length of the tower and blades is gradually increasing. Due to the significant superiority of conducting physical tests on large scaled specimen, such as tower and blades, hybrid simulation is widely used in structural seismic analysis. Combining the numerical simulation and physical testing, it has the ability to solve the problem of multiple loads facing by wind turbines. A software platform suitable for standard hybrid simulation of onshore wind turbine is developed based on Simulink. In order to consider the interaction between the blade deformation and the wind load in the process of hybrid simulation, the software OpenFAST for dynamic analysis of wind turbine under wind load has been developed to realize the transmission of data with Simulink step by step, which provides a new way to implement the hybrid simulation of wind turbines under operating conditions. The accuracy of the software platform is numerically verified, and the cost of time on computation of numerical substructure and data transmission between Simulink and OpenFAST is also tested.

Hao Hu, Zhu Mei, Yang Liu, Kao-shan Dai
Risk-Based Inspection Planning for Support Structure of Offshore Wind Turbine

The optimal allocation of deterioration control in risk-based inspection (RBI) planning is based on the pre-posterior analysis using Bayesian decision theory and expected utility theory. This paper applies the RBI planning in the area of offshore wind turbine foundation structure, aiming to minimize the life-cycle cost which takes the direct cost and the indirect consequence into account. The direct cost refers to the direct loss and the indirect consequence refers to the power loss due to the downtime of wind turbine. A monopile offshore wind turbine structure is analyzed in OpenFAST simulation package to demonstrate how to utilize RBI planning in the field of support structure of offshore wind turbine, in which the environmental condition is taken from the statistical data in North Sea. The case study show that the RBI planning can effectively reduce the expected life-cycle cost of offshore wind turbine.

Weiheng Zhang, Dagang Lu, Jianjun Qin, Min Liu, Michael Havbro Faber
Upper Bound Limit Analysis for the Stability of Elliptical Tunnels Based on the Node-Based Smoothed Finite Element Method and Second Order Cone Programming

The stability of 2D elliptical tunnels in cohesive-frictional soils are studied by using upper bound approach of limit analysis based on smoothed finite element method (SFEM) and node-based strain smoothing techniques (NS-FEM). According to the upper bound theorem of limit analysis, the stability of tunnels will be expressed as a second order cone programming (SOCP) problem following the Mohr-Coulomb (for 2D) yield criterion and the associated flow rule. This convex programming can be solved in fast and robust way by primal-dual interior point algorithm. In order to analyze the effectiveness of NS-FEM-based upper bound approach for the elliptical tunnel stability, especially to overcome the performance of volumetric locking under incompressible condition, several typical numerical tunnel models are established and analyzed. From the numerical results, failure mechanism of the elliptical tunnels can be revealed without the volumetric locking problem.

Feng-Tao Liu, Xi-Wen Zhou, Yan Zhang
Response of Soil-Structure with Respect to Different Shapes of Pile Cross-section Under Cyclic Loads in the Context of CO2 Emission

In the process of prosperous development of the construction industry, the problem of carbon emissions caused by material consumption is severe and cannot be ignored. The pile cross-section is an essential factor influencing the lateral resistance, while a reasonable pile cross-section can reduce material consumption and CO2 emissions. Thus, the behavior of piles with different cross-sections embedded in Toyoura sand under cyclic lateral load was studied numerically in this paper. This paper described how to use cyclic loads to simulate earthquakes, how to find the most unfavorable load, and the numerical analysis results, such as the lateral load-displacement curves and the cyclic accumulation of horizontal displacement of the head of the pile. This paper presented a new indicator (ρ) to represent the trade-off between the CO2 emission (represented by the consumption of the materials) and the seismic behavior, which helps in making engineering decisions. By comparing the results, it can be concluded that the lateral resistance of the solid square pile is higher than that of the solid circular pile by 39.98% under the most unfavorable cyclic load and ρs is 7.573, ρc is 16.066.

Linfeng Li, Jianjun Qin
Simplified Calculation of Waist Hole of Straddle Monorail Pin Bearing

To realize the horizontal displacement function of the bearing, a kind of pin bearing with a waist hole is applied to the straddle monorail viaduct system for the first time. Because there is no stipulation on the calculation of the pin bearing with waist hole in the domestic and foreign codes, based on the pin design formula of the steel structure design standard, this paper analyzes the key parameters that affect the force of the waist hole and establishes a simplified calculation formula of the waist hole, which can be used as a supplement to the relevant provisions of the code and can be used as a reference for the corresponding design.

Hui Wang, Shuyi Duan, Yanqiang Ji
Experimental and Numerical Studies on the Seismic Performance of Crawler-Type Connection Node

A kind of prefabricated external wall panel connection node is proposed in this paper. The node is simplified as a crawler damper and analyzed by quasi-static tests to investigate the influence of different materials on the mechanical properties of the node. The test results indicate that specimens made of cold-rolled Q235 and hot-rolled Q235 have excellent energy dissipation effects, but the specimens made of hot-rolled materials have better fatigue resistance and are more in line with the needs of practical use. In addition, based on the finite element analysis software ABAQUS, a specimen model was established for finite element analysis and compared with the mechanical test results to verify the reliability of the finite element simulation method. The influence of the height, thickness, and arc segments’ diameter geometric parameters of the crawler damper on its bearing capacity and energy dissipation capacity was studied. The variation of the load capacity and energy dissipation capacity of the damper with these geometric parameters is determined.

Yixin Zeng, Wei Lin, Jing Li, Yixi Hu, Zhilong Jiang, Peixing Xie
Experimental Study on the Lateral Performance of Traditional Wooden Structure with Bamboo-Woven Mud Infill

It is a typical practice to embed the bamboo-woven mud wall (also called wattle and daub wall, W&D wall) in the traditional Chuan-Dou wooden structure widely distributed in southwest China, such as Chongqing or Guizhou. Based on a large-scale field investigation in Chongqing, this paper had carried out detailed research on two specimens of bamboo-woven mud infilled wooden frames with different wall thicknesses for cyclic loading test, in order to study the influence of wall thickness on the lateral resistance of this kind of wall. The test results showed that bottom slip of all the bamboo-woven mud infilled wooden frames were obvious during the whole cyclic loading process. Increasing the wall thickness can obviously improve the bearing capacity and stiffness and energy dissipation capacity of the traditional Chuan-Dou timber frames, on the other hand, serious mud falling off may occur if the wall thickness is too large and this may become a safety hazard.

Yunyang Qi, Hao Huang
Seismic Response Analysis of Shallow Tunnel Under Simultaneous Oblique Incidence of P and SV Wave

The incident angle of seismic waves can significantly affect the seismic response of shallow tunnels. Based on wave field separation technology and equivalent seismic load method, a general 2D numerical model whose accuracy of the model is verified considering oblique incidence characteristics is established. A series of time-history analysis are conducted to study the influence law of P wave oblique incidence alone, SV wave oblique incidence alone and simultaneous incidence of P and SV wave (P-SV wave) on the dynamic response of shallow tunnels. The results show that (1) The seismic response of tunnels increases with the increasing of incident angle in small range. (2) For the same intensity level, the seismic response of structures under the obliquely incident SV wave is higher than that under P wave, while the vault and arch foot are vulnerable parts. (3) The seismic response resulted in the oblique incidence of SV wave alone is less than that under P-SV wave, which indicates the necessity of considering the simultaneous incidence of P and SV waves.

Dong-Dong Zhang, Yang Liu, Feng Xiong, Zhu Mei
Experimental and Numerical Investigations on the Structural Behaviour of the Joints in Aluminium Alloy Frames Supported Glass Curtain Wall

In-plane and out-of-plane structural behaviour of aluminium alloy joints connected by stainless steel bolts were investigated through experiments and numerical analyses. Coupon tests were conducted prior to the tests of joints to obtain the material properties of aluminium alloys. Then, six full-scale tests on the joints were conducted, considering different loading conditions and different locations of joints in aluminium alloy frames. Key structural responses of joints, including failure modes, moment-rotation curves, initial stiffness, ultimate moment resistances and corresponding rotation at ultimate moment resistances, were obtained from the tests and the joints were classified by the specification in EN 1993-1-8. The test results indicated that the flange of the vertical member and the bolts in the horizontal member need to be strengthened for joints subjected to in-plane and out-of-plane loads, respectively. Following the tests, numerical models verified by the test results were established to mimic the structural behaviour of joints. Through discussion of test and numerical results, design suggestions were proposed.

Mengyu Li, Chunyin Ma, Zhongxing Wang, Guoxing Li, Lulu Fan
Discussion on Key Problems of 3D Printing Concrete in Coastal Environment

3D printing concrete (3DPC) has the advantages of flexible design, high construction efficiency and less consumables, which meets the requirements of construction industrialization. The current research, forming the preliminary results of 3DPC, mainly focuses on the mix design, performance evaluation method and printing control technology. however, there are few studies considering the service environment condition. At the same time, the cement material consumption of 3DPC is too high currently, which is inconsistent with the dual-carbon target. Therefore, this study investigates and analysis the research literature of 3DPC at home and abroad, and summarizes its research progress, technical characteristics and problems, analyze the current problems of 3DPC, then a research framework and technical route is proposed for the green and low-carbon development of 3DPC in the coastal environment. and the key problems of them are point out, which is expected to provide exploration and reference for the expansion of 3DPC applications.

Xinyue Zhang, Weijiu Cui, Chengping Qu, Sheng Wang, Qi Yu
Experimental and Numerical Investigations on the Compression Behavior of Calcareous Sand-Rubber Mixture

Improving calcareous sand is of great engineering significance to the construction of man-made islands. At present, waste tire chips (i.e., rubber) have been tested to improve geotechnical materials for infrastructures such as road subgrades and foundations. However, the influence of rubber on the compression behavior of calcareous sand is still unclear. In order to observe this, the one-dimensional compression tests of the mixture with rubber content of 0%,10%, 20%, 30% and 50% and the numerical simulation of MatDEM were carried out. The experimental results showed that the ductility and high compressibility of rubber resulted in a higher compressibility and lower strength of the mixture, which may mitigate the degree of particle breakage. As the rubber content is greater than 20%, the intensity of the calcareous sand-rubber mixture is too low to be recommended for engineering. Further study will focus on the particle-particle, particle-rubber and rubber-rubber stress to clarify the mechanism of particle breakage mitigation.

Ziye Zhou, Hongjie Lin, Jiankun Liu
Stress Analysis of Narrow Steel Box Continuous Composite Beam Based on ABAQUS

The ABAQUS was used to analyze the stress of two narrow-width continuous composite steel box beams with different reinforcement ratios, and the rationality of the model was verified by comparing with the experimental data. Based on the model, by changing the strength grade of the composite beam wing plate and introducing the UHPC material, the stress condition of the beam negative moment area was improved. The buckling problem of the bridge deck was solved by filling the whole span with concrete. The simulation results showed that when the reinforcement ratio increased from 1% to 2%, the cracking load and yield load were significantly increased, and when the reinforcement ratio continued to increase, the enhancement effect was not significant. Only increasing the strength of the composite beam wing plate had no obvious optimization effect on the stiffness and yield strength of the composite beam. However, using UHPC material, the cracking load of the beam increased by 57.6%, and the deflection value decreased by 43.8% when reaching the cracking load. Compared with C40 composite beam, the yield load increased by 29.5%. The overall stress of composite beams was significantly improved.

Jing Huang, Shuai Liu, Yan Zheng, Xiaobei Liu
Optimization Design and Simulation of TMD for a Wind Turbine Based on SIMPACK

TMD plays a great role in the wind turbine vibration control under various working conditions, which will reduce the fatigue damage and prolong the service life. However, previous research and design generally adopted the finite element simulation, which is not consistent with actual project in model and load calculation, causing difficulty when applying technology transformation. Meanwhile, the damping performance of TMD in all directions and limitation of installation space in nacelle need to be studied further. Consequently, this study proposes a new TMD design, and then completes the combined model of turbine and TMD in the commercial software SIMPACK. Innovatively, typical working conditions are analyzed to establish the radial basis function neural network, which contribute to global optimization of TMD by using genetic algorithm. Besides, comparison of simulation results with and without dampers is given to verify the performance of designed TMD, taking the reduction rate of time history standard deviation as the index to evaluate damping effect. The final results indicate that the installation of optimized TMD can reduce the average force at tower bottom by 23.84% and the average bending moment by 18.29%. The results have been applied to TMD design in real engineering.

Yang Li, Chao Wang
Measurement and Analysis of Flow Velocity in a Large Air Duct Elbow System

Increasing large air ducts (hydraulic diameter over 2 m) have been applied in various projects. In the air conditioning system composed of large air ducts, the air distribution of air ducts should be thoroughly analyzed by to analyze the influence of diversion plate setting of duct elbow on the pressure loss and energy consumption of the system, so as to realize energy saving of ventilation and air conditioning system of the building. The background project of this paper is the mechanical and electrical installation project of Shanghai XinZhuang Metro Station Project. In this paper, a scaled model test was carried out to measure the pressure loss of duct bend of a large air duct system. By measuring the air velocity and pressure at different positions along the duct under different working conditions, parametric study was conducted to provide guidance to reduce pressure loss and noise of large air duct system with different elbow flow diversion system.

Yi Tang, Sen Yu, Xiaocheng Cao, Haidong Wang
Modal Identification of Underwater Precast Self-centering Segmental CFST Bridge Under Horizontal or Vertical Ground Motion Based on Covariance Driven Random Subspace Identification

Precast segmental self-centering concrete-filled steel tubular (PSCFST) bridges have good seismic performance and resilience. In recent years, researchers have carried out certain research on the seismic performance of this kind of bridge, while there is still a lack of research on modal parameters under earthquakes action. In order to further understand the vibration characteristics of PSCFST bridge under earthquake action, based on the modal parameter identification process of covariance-driven random subspace identification (COV-SSI), this paper analyze the modal parameters of PSCFST bridge under different water depth conditions and different ground motion directions using the shaking table test of PSCFST single-span bridge. In three different water depth environments, namely: water depth of 1.5 m, water depth of 1.8 m, and no water, seismic ground motion in vertical and horizontal (along the direction of the bridge) directions was added through shaking table test to obtain the acceleration response of the bridge. The signal is used as the input data of the covariance random subspace method to obtain the natural frequencies and damping ratios of the first four modes under 6 different working conditions. The analysis results show that the algorithm has a good identification effect on the modal parameters of the PSCFST bridge, in which, water has a small effect on the natural frequency but a large effect on the damping ratio. The COV-SSI method provides theoretical support for the application of structural health monitoring system in PSCFST bridges.

Mo Zhang, Yunfei Wang, Dan Zhang, Junfei Zhang, Ning Li
Earthquake Damages to Substation Buildings

The present study highlights the significance of conducting the appropriate seismic design of substation buildings. First, the seismic damage of substation buildings during past several earthquakes is summarized to illustrate the damage features of common substation buildings. Then, the current seismic practice of substation buildings is presented, focusing on the seismic performance of substation buildings in some numerical and experimental studies. At last, the research trend from performance-based design to resilience-based design of substation buildings is discussed to shed a light the development of seismic design of substation buildings.

Weixian Che, Yanfeng Wang, Baichong Pan, Xinghua Wang, Wenwei Zhu, Jingen Guo, Hantuo Dong
Automatic Object Detection of Construction Workers and Machinery Based on Improved YOLOv5

Automatic detection and localization of workers and machinery on construction sites through surveillance video is important to supervise on-site safety and construction process, which could develop civil construction management and services. However, it is difficult to detect all instances due to the extremely complex construction environment and numerous multi-scale objects. This paper proposes an improved YOLOv5 model to automatically detect and localize construction workers and 11 common types of construction machinery. Firstly, use the bidirectional feature pyramid network (BiFPN) layer for better multi-scale feature fusion ability; Secondly, 3 × 3 convolution layer is replaced by RepVGG block, which shows favorable accuracy-speed trade-off. The experimental results indicate that the mAP (mean Average Precision) of our proposed method is 87.32%, which is 2.12% higher, and inference time reduce to 5.7 ms per frame.

Yuanzhi Xiang, Jiayue Zhao, Wenjing Wu, Caifeng Wen, Yunzhong Cao
Study on Comparison and Selection of Grouting Pre Reinforcement Schemes for Underground Excavation Land Section of River Crossing Tunnel – Taking Rongjiang Fourth Road River Crossing Tunnel as an Example

Jiangxi Ganzhou Rongjiang 4th Road River crossing tunnel is the first river crossing tunnel constructed by mining method in Jiangxi Province. In order to ensure the construction safety of the underground excavation land section of the tunnel, based on the fuzzy analytic hierarchy process theory, this paper carries out the comparison and selection of grouting pre reinforcement schemes for the surrounding rock of the underground excavation land section of the river crossing tunnel. The research results show that: 1) according to the engineering properties of the surrounding rock in the concealed excavation land section of the Rongjiang fourth road river crossing tunnel, through the research on the grouting pre reinforcement scheme, the pre reinforcement engineering plans of high-pressure rotary jet grouting and sleeve valve pipe grouting are selected; 2) Based on the theory of fuzzy analytic hierarchy process, a comparison model of grouting pre reinforcement schemes for surrounding rock of underground excavation land section of river crossing tunnel is established. The comparison result of the model is that the high-pressure rotary jet grouting scheme is better than the sleeve valve tube grouting scheme.

Hongwei Zhang, Helin Fu, Hongyu Guo, Guijun Luo, Kaiyuan Zhang
Study on Impact Resistance of Corroded Concrete Beams

To study the mechanical properties and failure modes of corroded RC beams under impact, this paper verifies the accuracy of finite element model established by finite element software ANSYS/LS-DYNA through impact test of concrete beams conducted by Fujikake et al. Based on the verified finite element model, the influence of corrosion rate of reinforcement on the impact resistance of concrete beams was researched. The finite element analysis shows that the concrete spalling degree of concrete member under impact effect increases with the increase of steel corrosion rate. The higher the degree of steel corrosion, the more serious the concrete spalling. All the corroded RC beams at different impact heights exhibit flexural failure characteristics. Steel corrosion has a certain influence on the impact resistance of reinforced concrete members. At the same drop hammer impact height, the peak impact force decreases and the mid-span displacement increases with the increase of steel corrosion rate. When the height of impact is 2.4 m, the peak value of impact force decreases to 29.0%. when corrosion rate is 30.0%, and the mid-span displacement increases to 15.7% when it is not corroded.

Xiaofang Deng, Longmei Jin, Zhi Li
GPU-Accelerated and Machine-Learning-Based Wind Turbine Damper Optimization

Wind turbine wake flow generally has larger turbulence intensity compared with free flow, which would result in larger damage to downstream wind turbines. However, there still has no research about wind turbine vibration considering wake effect. Meanwhile, although previous research had reduced wind turbine vibration by installing dampers, there is still no systematic global optimization method for wind turbine damper. The question that whether optimized damper without consideration about wake effect can be directly applied in wind turbines affected by wake or not is still not clear. To this end, this study first investigates wake effect on downstream wind turbine vibration. Then, tuned mass damper and rotational inerter double tuned mass damper are installed in wind turbine tower to control tower vibration. Innovatively, this study proposes a global optimization method for dampers based on radial basis function neural network and genetic algorithm, which is significantly accelerated by GPU acceleration technology. As well, wake effect on wind turbine dampers is studied by comparing optimized dampers with and without consideration of wake. Optimized dampers can reduce at most 44% tower bottom equivalent fatigue load. Numerical results can provide references for choosing damper and damper optimization in real engineering.

Shi Liu, Yize Wang, Zhenqing Liu
Influence of Openings on Fluctuating Wind Pressure Characteristics of Large-Span Cantilevered Roofs

Based on the rigid pressure measurement test of the stadium large-span cantilevered roof. The influence of openings on the fluctuating wind pressure characteristics of roof is studied. Firstly, compare the roof of no opening and opening in some aspects, such as fluctuating wind pressure coefficients, skewness and kurtosis, and probability density functions. Secondly, the two types of roofs are divided into non-Gaussian regions based on the cumulative probability curve. Finally, the Hermite moment model is used to calculate the peak factor to consider the non-Gaussian distribution characteristics of the roof. The results show that probability distributions of fluctuating pressures within the vicinity of the windward-side edge, which appear serious deviation and bulge compared with those of standard Gaussian distribution, and which present typical non-Gaussian characteristics. However, the opening can effectively slow down the flow separation phenomenon in the edge opening area, which weakens the non-Gaussian characteristics. The area located in the middle and rear of the roof with smooth airflow still obeys gaussian distribution after opening. At last, the reasonable values of peak factor of the two types of roofs are put forward.

Min Zhang, Pailin Fang, Qizhou Liu, Dan Lu, Dan Pan
Influence of Scour Depth on Pile Group with Complex Configuration in Clay

The pile foundation in the current and marine environment will be affected by the scour of the current, which will cause the soil around the pile to be eroded, thereby reducing the bearing capacity of the pile. Many studies were pointed out that scour is one of the main reasons for bridge failure. However, A few studies have investigated the change in bearing capacity of laterally loaded pile groups under scour conditions. Based on the LIJIATUO Bridge 5# and 6# pile groups foundation and corresponding geological data on the JIALING River in Chongqing, a number of numerical studies are conducted to examine the lateral behavior of two pile groups with complex configurations under different scour conditions by using three-dimensional FEM model. The MCC model was adopted to describe the mechanical responses of soil. The formation process of the local scour hole around pile groups was simulated using the life and death element method. By comparing the bearing capacity of laterally loaded pile group and laterally loaded isolated pile under the same scour conditions. The results show that the increase in scour depth will reduce the bearing capacity of the laterally loaded pile group. The group effect of pile groups under lateral load will change with the varying scour depth. Among them, the scour depth has the most excellent effect on the group effect of the leading row piles.

Zengliang Wang, Hang Zhou, Longyong Tong
Finite Element Simulation Analysis of Double-Wall Steel Boxed Cofferdam for MaLuKou Zishui River Bridge on Guanzhuang-Xinhua Expressway

Steel boxed cofferdam is a facility for underwater foundation construction, which has the advantages of high stiffness and simple construction. For the safe of steel boxed cofferdam, its overall mechanical properties need to be studied. Take the double-wall steel boxed cofferdam of MaLuKou Zishui River bridge for an example, the finite element model is established by MIDAS/civil. Its mechanical properties in different conditions are discussed and analyzed in this paper. Research shows: (1) The stress state of the double-wall steel boxed cofferdam is good, and the stress of the structural members and the bond stress of the bottom concrete meet the design requirements. (2) In the construction process, extreme stress occurs during pumping, which is the most dangerous working condition. (3) The stress of wallboard and steel pipe support is higher during pumping, and the pumping condition is the design control condition of wall and steel pipe support. (4) When pouring the bottom concrete, the stress of the bottom member is higher, which is the design control condition of the bottom plate. It is of great significance to the design and construction of the steel boxed cofferdam.

Lu Yi
Defect Detection and Damage Evaluation of Steel Rods Based on Ultrasonic Guided Waves

Structural defects caused by corrosion and fatigue of steel rods are the main problems in cable-supported engineering. Compared with the traditional ultrasonic detection methods, guided waves have attracted the attention of more and more researchers because of the one-place excitation, long-distance propagation, and wide-range detection. In this paper, the propagation characteristics and laws of the guided wave in the rod are theoretically studied, and the dispersion curve of the rod-shaped structure is deduced. Then, a large number of numerical simulation experiments are carried out for the steel rods with defects using ABAQUS software, and the optimal excitation mode and excitation frequency are selected. Finally, the relationship curve between the evaluation index and the defect depth can be obtained by calculation, which can be used to describe the damage of the steel rod quantitatively.

Han Zhu, Jing Zhang
Study on Enhancing the Performance of Unglazed Solar Air Collector by Attached Jet

This paper creatively designs a unglazed solar air collector using attached jet to enhance heat transfer. The collector enhances the heat exchange between air and Heat collector plate by creating a specific structure to block and reflect the jet and make it impact the heat collector plate. The structure can not only strengthen the heat exchange, solve the problems of insufficient heat exchange and heat loss of direct exposure to the environment of the unglazed heat collector, but also make up for the reduced effective heat collection area due to the opening on the heat collector plate. Through the simulation and analysis of the internal flow and heat transfer characteristics of the collector, it is found that the attached jet effect is obvious, which can better improve the above problems of the unglazed collector. The effects of slit width and baffle diameter on heat collection efficiency are analyzed by numerical simulation. Finally, the experiments showed that the collector’s heat collection efficiency remained stable throughout the day, significantly improving the thermal performance of the traditional unglazed permeable solar collector.

Jian Jin, Jianjun Hu, Gui Hu, Shenghua Du
Experimental Investigation on Stress-Strain Curve of Phosphogypsum Under Uniaxial Compression

To study the stress-strain relations of phosphogypsum (PG), 36 samples with different mix proportions were tested under uniaxial compression. The failure mode, measured curve, elastic modulus and Poisson’s ratio were analyzed in detail. The results show that all samples showed similar failure modes, and all stress-strain curves can be divided into 3 stages. The strength of the sample increases with the reduction of the water-solid ratio, and the elastic modulus increases with the increase of the compressive strength. The mix proportion has little effect on the peak strain and Poisson’s ratio of the PG sample. Furthermore, a stress-strain model was developed based on the mathematical fitting method, comparisons between the test and calculated curves showed that the proposed model has a good accuracy.

Li Zhou, Song Hu, Chao Yin, Yifeng Xu, Qingyu Zou
Numerical Simulation on Progressive Collapse Resistance of RC Beam-Slab-Column Substructures

In order to study the progressive collapse resistance (PCR) performance of unequal-span reinforced concrete (RC) spatial beam-slab-column substructures, numerical analysis based on the experimental study of the PCR performance of RC structures under central column failure completed by Qian was carried out. A finite element (FE) model was established by the high precision FE software ANSYS/LS-DYNA, and the accuracy of the model was verified by comparing with experimental results. Based on the verified FE model, the extended parameters of the model were analyzed, including the effects of concrete strength, slab thickness and slab reinforcement ratio on collapse resistance of RC spatial beam-slab-column substructures and mechanism of load redistribution. The FE analysis results showed that the increase of concrete strength would increase the first peak load of the structure but weaken the deformation capacity of the member. Appropriately increasing the slab thickness can significantly improve the bearing capacity of the structure. And with the increase of the reinforcement ratio at the bottom of the slab, the resistance to catenary mechanism was improved obviously, but the deformation capacity of the structure was weakened. In the whole process of RC frame collapse, the contribution of the slab to resistance was about 46% on average according to load redistribution analysis.

Yi Zhang, Yirong Gao, Xiaolan Yuan, Bing Liu
Effect of Vertical Load on Lateral Response of Single Piles in Coral Sand

Coral sand is distributed widely between 30 °S and 30 °N, and its mechanical properties are significantly different from general siliceous sand. To investigate the pile-soil lateral response in calcareous sand foundation under the vertical-horizontal load combinations, a series of effective numerical studies were conducted and analyzed. The lateral load-displacement curves, pile deformations, soil stress fields, and soil displacement fields were analyzed in detail. The combined loaded piles show a significant increase in the lateral capacities, or a corresponding reduction of pile displacements as compared to pure lateral loaded pile. In addition, the existence of vertical load can increase the stresses of sand around pile and weaken the rotation flow zone of sand near the pile tip.

Chunyan Wang, Xuanming Ding
Study on the Effect of Pier Explosion on the Performance of RC Curved Girder Bridge with Double-Column Pier

A finite element (FE) model for reinforced concrete (RC) double-column pier curved continuous box girder bridge was established using ANAYS software. The FE modeling method was verified based on a pier explosion test. Considering two types of explosions including vehicle-borne explosion and knapsack explosion, the sensitivity of the columns in side span and mid-span under the explosion load was studied. The effect of the explosion location at different parts of the weak pier is also studied. The results show that the inner column of the side span was the most vulnerable column, and the weakest part for this column was the connection between column and bridge deck. The above research results provide a certain guiding significance for the design of double-column pier curved box girder bridge against explosion.

Guohua Song, Sandeep Gharti Magar, Mingming Yang, Jian Su
A Comparison Between PDEM-Based Approach and Linear-Regression-Based Approach in Seismic Fragility Assessment: Application into Low-Rise Frame Buildings

In this paper, a comparison between probability density evolution method (PDEM)-based approach and linear-regression-based approach in seismic fragility assessment is performed, and an application into low-rise frame building is conducted for implementation. The principles of the two fragility approaches are introduced first. The PDEM-based fragility approach has solid foundations in the reliability field and is expressed as a non-parametric form without predefined fragility shapes, while the linear-regression-based fragility approach is expressed as a classic parametric form, commonly under the assumption of lognormal distributions. Then a 3-span-4-storey reinforced concrete frame (RCF) building, which represents the existing buildings with large quantities in China, is used for seismic assessment by the two approaches. In general, the application shows the similar tendency of fragility curves for the two methods, and verifies the effectiveness of the non-parametric PDEM-based approach for seismic performance assessment. Comparatively, the PDEM-based approach omits the heavy computing burden as Monte Carlo simulation, and reflects the fragility characteristics with considerable accuracy as linear-regression-based approach, which turns on a new path for the fragility assessment scheme in the performance-based earthquake engineering.

Xuyang Cao, Jigang Xu, Shizhi Chen
Study on the Fissure Propagation of Jointed Rock Slope Under Unloading Condition

The rock mass unloading is closely related to the change of geological environment, such as river valley down-cutting, frequent rainfall and evaporation, and slope excavation. For the jointed rock slope with complicated structure, these changes may trigger the propagation of cracks, posing a serious threat to slope stability and construction safety. Thus, it is necessary to analyze the fissure propagation of jointed rock slope under unloading condition. Currently, traditional finite element method (FEM) has been widely used to analyze the failure of slope because of its rigorously theoretical system. However, for discontinuous problems such as crack propagation, the result in FEM often presents high stress concentration in crack tip (numerical singularity), causing calculation to abort. In this connection, this paper intended to introduce cohesive zone model (Theory of cohesive element) from fracture mechanics to deal with the numerical singularity, and meanwhile adopt Voronoi diagram algorithm for rapidly modelling the structural planes. Firstly, a jointed rock slope model was taken as an example, discontinuity network of which was generated by Voronoi diagram, and then 0-thickness cohesive elements were embedded into structural planes to establish a numerical model. Finally, the study compared and analyzed the crack evolution of slope under different unloading conditions by changing the geometry of slope.

Sheng Li, Chen Yang
Determining and Estimating the Fracture Risk of Diaphragm Wall from Observed Lateral Deflection

Due to the great uncertainty and complexity in the underground environment, the investigation and analysis of the internal force of the diaphragm wall are a highly challenging problem. Aiming to achieve the safety estimation of foundation pit in deep excavation, this paper proposes a framework for the calculation of bending moment and determination of fracture risk of the diaphragm wall. Firstly, the five-point smoothed cubic smoothing algorithm is used to eliminate the adverse impact of data noise on the curve fitting. Secondly, the developed natural spline smoothing algorithm is used to implement the curve fitting by establishing the connection of piecewise approximation and smoothness. In addition, three case studies are analyzed to verify the effectiveness and applicability of the developed algorithm. Thirdly, the curvature is obtained by the second derivative of the fitted curve to calculate the actual bending moment with the elastic bending theory. Finally, the efficiency factor of bearing capacity (K) is calculated to investigate the behavior and determine the fracture risk level of the diaphragm wall. Meanwhile, a deep well excavation in Shanghai’s Hard X-ray project is utilized as a case study for demonstration purposes. The contribution of this research lies in that the approach can be effectively applied to calculate the bending moment of the diaphragm wall and implement the risk assessment for deep excavation engineering.

Xiong Wang, Yue Pan, Mingguang Li, Jinjian Chen
Hysteretic Performance of Self-centering Glulam Beam-To-Column Connections with Steel Core Panel Zone

Resilient timber structures have arisen global attention due to the advantages in seismic resisting, of which the low repair cost and acceptable downtime are most favored to the public. Post-tensioned glued-laminated timber (PT-GLT) connections played a key role in assigning timber structures the seismic resilience. With the shortening of steel tendons, members connected to the PT-GLT connections are pulled back to their original position. However, there’s still room for improvement. Based on the authors’ previous experimental research on PT-GLT connections, the efficiency in concentrating damage was low. The connection was unable to entirely depend on the replaceable energy-dissipating elements to dissipate energy. The accumulative damage yielded to the permanent compression deformation on the timber column face, which was not recoverable This paper presents a preliminary study on the feasibility of a method for improving the PT-GLT connections. It was attempted to use a steel member in the intersection of the beam and column. The steel member provided a stiff foundation when the rocking occurred. A cyclic loading test of two PT-GLT connections was conducted. A comparison was made between the connections with and without the improvement method. It was proved that the method was beneficial to improve the connection efficiency in the energy dissipation, connection ductility, and stiffness.

Zheng Li, Fei Chen, Xiaofeng Sun, Zhan Shu, Minjuan He
Behavior of CFRP-Confined Basalt Fibre Reinforced Recycled Aggregate Concrete

The research findings of an experimental study on the axial compressive behavior of carbon fibre reinforced polymer (CFRP) confined basalt fiber (BF) reinforced recycled aggregate concrete (RAC) are presented in this paper. Six CFRP confined BF reinforced RAC (BFRC) short columns were tested under axial compression. The effects of the recycled concrete aggregate (RCA) replacement ratio and CFRP constraint form were studied. The failure mode, stress-strain curve, finite element model and ultimate bearing capacity prediction are analyzed in detail. The results show that the failure modes of unconfined BFRC are similar, while those of CFRP-confined BFRC are different. CFRP constraints can effectively improve the bearing capacity and deformation capacity of BFRC square columns, and the degree of improvement is positively correlated with the thickness and the confined area of CFRP. Based on the experimental data, a simple prediction model of ultimate bearing capacity is established. The model has good accuracy.

Yi Xu, Jiangfeng Dong, Qingyuan Wang
Influence of Hammer Geometry on Impact Performance of RC Beams

Finite element models were created based on the impact test of RC beams to examine the influence of hammer curvature radius on the resistance of RC beams under drop weight load. The influence of varied hammer curvature of drop weight on the dynamic response of RC beam under impact load was investigated using a confirmed finite element model. The findings showed that the FE model accurately predicted the dynamic response of an RC beam under impact load. It is also discovered that increasing the curvature radius of the hammer increases the impact loading rate and the peak of impact force. The peak value of impact force recorded by the drop hammer is more stable at varying beginning inclination degrees of the drop weight when the curvature of the hammer is not zero.

Tianqi Xue, Xiaolan Yuan, Xin Zhang, Zhi Li, Xiaofang Deng
Component-Based Simulation on Progressive Collapse of a 2D-Framed Steel Structure Under Debris Impact

In this study, component-based models for FP joints and WUF-B joints were proposed and validated against impact tests. Then a steel-framed structure with 10-floor designed by NIST was studied by removing column method with the application of the models. The locations of the removed columns, including different floors and bays, and the number of the removed columns were considered as variables. The simulation results showed that removal of a column located at a lower floor, contrasted with that at a higher floor, can cause a larger increase of axial forces of the columns at the same floor with the removed ones. The vertical displacement at the removed columns decreased with the floor number decreasing. Since the gravity bay was more vulnerable than the moment bay, column removal at the transition area would lead to the greatest change of axial force occurring at the column belonging to the adjacent moment bay. In addition, a sufficient lumped mass was required to trigger the progressive collapse of structures.

Yufang Yuan, Kang Chen, Bo Yang
Analysis of Mechanical Properties of Turbogenerator Foundation Based on ANSYS

As a working platform supporting the normal operation of the generator set, the turbo-generator foundation, its dynamic characteristics are very important to the safe operation of the whole set. In this paper, a finite element model was established according to the measured size of the turbine generator foundation, and the finite element software ANSYS was used to perform a static analysis on the foundation of the turbo-generator, and the deformation and stress cloud diagrams were obtained. The results shown that the local stress concentration phenomenon occurred in the foundation, which leaded to the high tensile stress at this stress position of the foundation. Then, the modal analysis of the foundation was performed to obtain the natural vibration characteristics of the foundation. Then the time-history analysis and calculation of the foundation structure under earthquake action were carried out. The results shown that the foundation of the turbo-generator met the seismic requirements, and the earthquake action had little influence.

Mingyi Tang, E Wenqi, Cong Zeng
Mechanical Properties of Spray-Based 3D Printed Micro-cable Reinforced Concrete

Spray-based 3D (S-3D) printing is an intelligent architectural technology by spraying concrete layer by layer, which can solve the problem of collaborative construction between 3D printing and reinforcement. This paper studies the feasibility of S-3D printed concrete with reinforcement. Effects of micro-cables diameters with 0.6, 0.8 and 1.0 mm on the flexural properties of S-3D printed micro-cable reinforced beams are considered. In addition, the interfacial bonding properties between micro-cable and concrete is observed by scanning electron microscope (SEM). The results showed that the ultimate flexural strength of S-3D printed micro-cable reinforced beam is improved by 43.4%–114.1% with the ductility improved by 58.4%–315.7%, respectively, which benefits the firmly bonded interface between micro-cable and concrete. This paper provides an effective method to improve the cooperation between 3D printing and reinforcement.

Ji Zhou, Guanyu Hou, Xiongfei Liu, Qi Li, Li Wang, Jixiang Li
The Distributed Hybrid Test and Validation of Multi-substructural Space Steel-Braced Frame Models Based on OpenFresco

The distributed hybrid test (DHT) is a new structural seismic test method, which is created to accommodate the increasing size and complexity of the test structure. Based on the OpenFresco platform, this paper introduces the principle and system components of the DHT for multi-substructures, and describes the modeling process, parameter selection and test system network construction process of the DHT model in the finite element analysis software OpenSees Navigator. A multi-story space steel-braced frame model is used as the research object to conduct the DHT, and the good loading accuracy and communication performance of the test system are proved. OpenSees Navigator was used to establish pure numerical models of the global structure respectively, and the analytical results of both were compared with the results of DHTs to prove the applicability and accuracy of the proposed test method.

Tengfei Li
Kalman Filter Based Adaptive Control for Real-Time Hybrid Simulation with Nonlinear Substructure

Real-time hybrid simulation (RTHS) plays an important role in obtaining the structural responses under dynamic loads. However, the nonlinearities in physical testing system often induce time-delay, which is detrimental to RTHS. To deal with this issue, a Kalman filter based adaptive delay compensation (KF-ADC) method had been proposed based on the discrete system model, whose parameters is estimated by Kalman filter (KF) algorithm. The delay compensation method was validated through a Benchmark problem in RTHS. This study intends to further investigate the performance of KF-ADC dealing with nonlinear physical substructures (PS). Virtual RTHSs are carried out on PS with bilinear and Bouc-wen restoring force characteristics, respectively. The results of virtual RTHSs reveal that the KF-ADC has an excellent tracking performance for nonlinear physical substructure and is beneficial for improving the accuracy and stability of RTHS.

Wei Huang, Xizhan Ning
Comparative Analysis of Tunnel Structures with Different Sections in Open Excavation and Buried Section of Urban River Passage

Based on the engineering background of the cross-river tunnel in the Rongjiang New District of Ganzhou, this paper uses Midas Gtx to establish three different tunnel cross-section structures: rectangle, polyline, and arch, and compare and analyze their ability to withstand bending moments and shear forces. Deformation, material consumption. Finally, the best section form is obtained. Studies have shown that under the conditions of large-section tunnels, arched tunnels have better mechanical performance. The maximum bending moment that arched tunnels can withstand is 47% of rectangular tunnels and 54% of broken-line tunnels. The structural deformation of the arch tunnel is the smallest, the maximum deformation of the rectangular tunnel is 19.97 mm, the maximum deformation of the broken line tunnel is 18 mm, and the maximum deformation of the rectangular tunnel is 15.6 mm. At the same time, the arched section structure is more economical in terms of material consumption. The concrete consumption of the polyline structure tunnel is 1.44 times that of the arch tunnel, and the concrete consumption of the rectangular structure is 1.67 times that of the arch structure. Under the same supporting conditions during construction, the safety reserve of the arch tunnel is higher.

Hongyu Guo, Helin Fu, Guijun Luo, Hongwei Zhang, Kaiyuan Zhang
Study on Flexural Behavior of Coral Concrete Beams Reinforced with BFRP Bars

Coral concrete structure reinforced with fiber reinforced polymer (FRP) bars is a new type of structure with broad application prospect in island construction. To this end, the failure pattern, midspan deflection, concrete strain, basalt fiber reinforced polymer (BFRP) bars strain and crack characteristics of coral concrete beams reinforced with BFRP bars (CCBRB)were analyzed through the three-point flexural tests. The test results showed that the CCBRB have two failure modes: flexural failure and shear failure, and the strain of mid-span concrete conforms to the plane section assumption. The flexural behavior of CCBRB is similar to that of ordinary concrete beams reinforced with BFRP bars (OCBRB). Reinforcement ratio increased from 1.22% to 2.34%, the cracking load and ultimate load of CCBRB increased by 33% and 25% respectively, and the mid-span deflection, crack width and average crack spacing decrease by 30%, 50% and 66% respectively. The cracking load of all specimens is 15–20 kN, about 10% of the ultimate load. CCBRB has a certain deformation recovery ability. The flexural capacity of CCBRB is calculated by the formula derived by Wang et al. The calculated value is closer to the experimental value.

Yi Zhang, Baikun Chen, Xiaolan Yuan, Bing Liu
Stochastic Model of Typhoons Along the China Coast and Its Application into Risk Assessment of Sea-Crossing Bridge Under Multiple Hazards

Typhoon-induced strong wind, extreme wave, and storm surge pose a significant threat to the structural and operational safety of a sea-crossing bridge. However, historical typhoons are usually insufficient in determining extreme hazards. Stochastic modeling of typhoons can expand the TC database and has been widely used in the risk assessment of TC-induced hazards. This paper introduced a full-track stochastic model to generate synthetic TCs based on historical TCs and climatology data along the China coast. A variable geo-graphical sampling approach is used to capture spatial heterogeneity. The track model is derived using the Cartesian coordinate system and considers the statistical characteristics of TC lysis. The one-dimensional ocean model is included to consider the ocean feedback on the typhoons. A catalog of 10,000-year synthetic typhoon events around the China coast is then generated by the developed stochastic typhoon model. The practical applications of the developed model are illustrated by an example sea-crossing cable-stayed bridge. The wind, wave, storm surge and current at bridge site under all the selected synthetic typhoon events are simulated by SWAN+ADCIRC. The joint probability of the typhoon-induced extreme conditions is established using the Copula theory. The environmental contour with a given return period is then obtained by the inverse first order reliability method. The stochastic dynamic responses of bridges during typhoons are finally investigated based on the obtained environmental contour under typhoons. This paper provides an insight into the risk assessment of the sea-crossing bridge under typhoon-induced extreme conditions in a life-cycle context.

Kai Wei, Zhonghui Shen, Xi Zhong, Zhiyu Bai
Comparison of Stability of Four Numerical Integration Methods Under Negative Stiffness

Numerical Integration Algorithm plays a very important role in real-time hybrid experiments. Based on the Newmark (γ = 1/2, β = 1/4) average constant acceleration algorithm, the stability analysis equations of Chang Algorithm, CR Algorithm and TL Algorithm under the condition of negative stiffness were derived by using the principle of positive stiffness analysis. The stability of the four algorithms under the condition of negative stiffness was analyzed by Matlab, and the stability characteristics of the four algorithms were studied by changing the integral time interval, damping ratio and stiffness ratio. The research findings indicate that when stiffness is negative, the Newmark average constant acceleration algorithm (γ = 1/2, β = 1/4) is no longer unconditionally stable, whearas the other three algorithms are all unconditionally stable. The Chang Algorithm has the best stability, while the CR algorithm is nearly as stable as the TL algorithm. It is suggested that while performing hybrid testing with probable negative stiffness, the numerical integration algorithm should be carefully chosen.

Fantao Meng, Jianfeng Zhao, Xingqun Ruan
Study on Phase Change Process of Heat Source for a Water Source Heat Pump

Allowing water phase change to release latent heat to provide heat for water source heat pump system can increase the running time of heat pump unit and reduce the use of auxiliary heat source. When water freezes and releases latent heat to provide heat energy for heat pump unit, its heat transfer process is more complex. This paper mainly studied heat transfer characteristics of ice-water phase change for a spiral coil heat exchanger. Firstly, the phase change process of water was studied experimentally. Then, the numerical model was established based on the experiments and the model was verified by the experimental data. Finally, the temperatures and liquid fraction in the heat exchanger container were studied by the verified numerical model.

Junhua Wu, Nuo Wang
Bidirectional Hybrid Simulation of a Six-Story Full-Scale Frame Specimen with Incomplete Boundary Conditions

It is imperative to carry out full-scale bidirectional hybrid simulations to accurately reproduce the responses of complex structures under earthquake excitations. To study the seismic performance of a six-story steel frame structure, a bidirectional hybrid simulation was carried out on a six-story, one-bay one-span experimental substructure by HyTest. In the test, only three degrees of freedom in the floor plane were considered. Four large-ton actuators were used for loading onto each floor. In this case, there was a problem with redundant actuator control. The control mode of “three displacements and one force” was used to complete the bidirectional test study, in which the redundant actuator is operated in force control mode. Furthermore, the “table-type” experimental substructure has a strong problem of incomplete boundary conditions. Thus, a hybrid simulation method with incomplete boundary conditions based on restoring force correction was proposed. The numerical results show that this method can effectively solve the problem of incomplete boundary conditions well and is a promising method.

Shangzhang Wang, Ge Yang, Liang Tang, Zhen Wang, Bin Wu, Yanfang Liang, Zhen Tian, Jiajun Xiao
Main-Aftershock Modeling According to Measured Records

At first, the coherence between main and aftershock measured records is systematically studied, and a Fourier trigonometric series model for the coherence function is proposed on the basis of this. After that, the parameters of evolutionary power spectrum density (EPSD) function model of main-aftershock ground motion are determined using the best square approximation. At last, to realize the dimension-reduction modeling of main-aftershock ground motion, it is regarded as a one-dimensional two-variate (1D-2V) stochastic vector process simulated by the POD-based dimension-reduction representation method. Thus, the dimension-reduction modeling for main-aftershock ground motion according to measured records is achieved with merely two elementary random variables. Numerical results show that the representative samples are consistent well with the measured records in terms of the coherence and the response spectrum, which demonstrates the correctness of the proposed main-aftershock model and the effectiveness of the dimension-reduction modeling method. It provides a positive way for the accurate dynamic response and reliability analysis of engineering structures subjected to main-aftershocks.

Zixin Liu, Yunmu Jiang, Zhangjun Liu, Xinxin Ruan
Study on Mechanical Performance of Column Base Joint with Slip-Friction Arc Endplates

In order to study the mechanical performance of column base joint with slip-friction arc endplates, the finite element simulation analysis of this joint is carried out. By changing the radius of arc endplate, axial compression ratio, and other parameters, the effect of different parameters on the bending capacity, joint stiffness, and bolt group force distribution of the joint is analyzed. The results show that the slip behavior of the column base joint is the best when the arc endplate radius is 0.7H (H is the height of the column section); This column base joint is semi-rigid and has good rotation capability. Based on the force distribution of the bolt group in the finite element analysis, the neutral axis of the bolt group is assumed to be located at the outermost row of bolts. Through theoretical analysis, the calculation formula for the sliding threshold of this joint is obtained. Compared with the simulated value, the two are in good agreement by using a correction coefficient of 0.75.

Chengyu Li, Zimeng Lai
Effect of Tung Oil on Mechanical Behavior of Silica Sand

Cemented sands have great potential as construction materials compared with clean sand due to the higher strength, but they have insignificant environmental benefits such as high embodied energy and carbon footprint. To provide an environmentally friendly, cost effective and reliable method to create an engineered soil, this study investigated on how Tung oil affects the mechanical behavior (strength and stress-strain behavior) of silica sand. Sand is mixed with a certain concentration (5%) of Tung oil. Heating could accelerate the equilibration of Tung oil-sand mixture and may contribute to the increase of mechanical strength compared with those at normal temperature condition. Therefore, conventional unconfined uniaxial compression tests are performed on sample equilibrated at 60 ℃ for different durations of heating. The Tung oil-sand mixture was found to exhibit (1) brittle failure under compression, (2) shorter time of equilibration and increasing compressive strength with longer duration of heating within 14 days.

Ke Chen, Sérgio D. N. Lourenço
A Study on Wind Resistance of Steel Arch Pedestrian Bridge

Pedestrian bridge is an important part of urban landscape. On the basis of satisfying the function of pedestrian traffic, it gradually steps forward to the comprehensive requirements of light structure, unique shape, large span, high bearing capacity and convenient installation. With the increase of bridge span, bridge structure becomes more portable and flexible. The wind resistance of bridge structures is increasingly prominent, especially for the flutter stability and eddy stability of bridges, which have become the key factors directly affecting the further growth of bridge span. Taking a steel arch pedestrian bridge in Guangzhou as an example, the flutter stability and eddy stability are investigated. The result shows that the bending-torsional coupling critical wind speed of flutter and separation flow flutter is less than the critical wind speed of flutter, suggesting that the flutter will not occur in the design reference period.

Jiahua Xian, Junfeng He, Shaocai Zhu, Minting Zhong
Research on Impact Resistance of H-shaped Steel Beam

This paper established a fine finite element model based on the impact test of H-shaped steel beams completed by Huo Jingsi et al. From Hunan University, in order to verify the accuracy of the finite element model. The paper used the validated finite element model for parametric analysis to study the impact of hammer geometry and boundary conditions on the impact resistance of steel beams. According to the parameter analysis: changing the hammer head geometry leads to changing the contact stiffness, so the impact force time-history curve changes; when the steel beam boundary condition is changed from hinged to rigid connection, the bearing on the beam is weakened, so the impact force is greatly reduced, the beam span deflection increases.

Yunhao Weng, Shihong Li, Xiaolan Yuan, Tianqi Xue
Segmental Prefabrication and Assembly Technology of Composite Box Girder with Corrugated Steel Webs

The three approach bridges of the Jiangxinzhou Yangtze River Bridge in Nanjing are prestressed concrete box girder bridges with corrugated steel webs, which is the first in the world to adopt the process of short-line matching prefabrication and cantilever assembly by bridge erector. A series of new technologies and equipment are proposed for the construction process from the manufacturing of corrugated steel webs to the matching prefabricated and cantilever assembly of composite beams, such as a special matching prefabricated template system, manufacturing of corrugated steel webs in yard by short-line matching method, technological process of molding with partial mode for steel cage and high precision cantilever assembly by bridge erector. On this basis, combined with field measurement and numerical simulation, the mechanical behavior of segmental precast assembled box girder with corrugated steel webs during construction is revealed.

Huijun Shen, Hehui Zheng, Fei Tian, Hao Dai
Correlation of Spectral Shapes of Horizontal and Vertical Ground Motions at the Same Period Based on Copula Function

Correlation and joint distribution model of spectral shapes of horizontal and vertical ground motions are important for the study of some applications. This study investigates the correlation and joint distribution model of the epsilons between vertical ground motions and associated horizontal ground motions at the same period via copula technique. The correlation of spectral shapes of horizontal and vertical ground motions based on four sets of horizontal and vertical NGA-West2 GMPEs are respectively studied, and a pair of horizontal and vertical GMPEs is selected for illustration. The joint probability distributions between horizontal ground motions epsilons and vertical ground motions epsilons via copula functions have been built, and then the conditional mean epsilons of vertical ground motions are calculated to verify the accuracy of the correlation of spectral shapes of horizontal and vertical ground motions. It has finally been found that epsilons of horizontal and vertical ground motions at the same period follow bivariate normal distribution. The correlation and joint distribution model of spectral shapes of horizontal and vertical ground motions from this study could be used as a theoretical basis for the site-specific spectrum generation in the future.

Xiaolei Wang, Zixu Zhao, Ruiguang Zhu
Hydrophobicity Assessment of Sands Treated with Tung Oil

Hydrophobic (or water repellent) soils have been reported worldwide. Soil hydrophobicity shows significant effects on water infiltration, water movement, evaporation, and soil strength. The unique properties of hydrophobic soils have been recognized by geotechnical engineers. They have been considered as novel construction materials for ground infrastructure. Synthetic hydrophobic soil was then proposed as it can be more economic, sustainable, and durable. Artificially inducing soil hydrophobicity can be obtained by using hydrophobizing agents, e.g. silane compounds and fatty acid. This paper presents a study of synthetic hydrophobic sand treated with Tung oil, a natural vegetation oil. The soil hydrophobicity was assessed through varied methods (contact angles, water drop penetration time and water entry pressure). Relationships between different hydrophobicity indicators and the amount of the applied Tung oil were investigated. The most efficient concentration for applying Tung oil to sand was proposed.

Xin Xing, Sérgio D. N. Lourenço
Study on Essential Maintenance of Long-Span Bridge in Railway

Bridge is one of the most critical structures on the railway. Steel structure is widely applied in the long-span bridges crossing natural obstacles such as canyons, rivers, and lakes. The focus of the long-span bridge is gradually diverted from design to maintenance. The points of maintenance of a long-span railway bridge in operation are discussed in this paper. The basic principles of maintenance are proposed. In this paper, spherical bearings, suspenders, and bolted connections are defined as key components for long-span railway steel bridges. The inspection strategies and typical diseases of spherical bearings are introduced. The testing methods and contents of different types of suspenders are listed. Numerical control constant torque electric wrenches are recommended for inspecting high-strength bolts, and the delayed fracture factors of high-strength bolts are discussed. The essential maintenance in this study is recommended for long-span bridges in railway.

Xin Jiang, Zhouyu Zhang, Peng Wang, Xinlin Ban, Min Huang, Jichao Guo
Load-Path Method for Design of Disturbed Regions in Concrete Structures

This study develops a quantitative load path method for the shape selection of the strut-and-tie models in disturbed regions (D-regions) of structural concrete. Firstly, quantitative load paths are generated in two ways. One approach is to develop a computer-based tool to plot principal stress trajectories seen as load paths. Another approach is to give mathematic descriptions of the load paths based on their geometric boundary conditions in some typical D-regions. Then, the characteristics of the load paths are explored. With the help of the quantitative load paths, the shape selection of the strut-and-tie models can be significantly facilitated. The suitability and efficiency of the proposed methodology are demonstrated in three types of D-regions, including deep beams, bottle-shaped struts, and dapped beams.

Jianlin Wang, Zhiqiang Wang, Zhiqi He
A Study on the Design Strategy of Living Space Renovation Under the Background of “Aged Caring at Home”

The aging of the population has become a problem that cannot be ignored in China. Due to the current economic development in China, it is not possible to copy the aging system of western developed countries for the time being, and the “aging in place” model will become the first choice for most of the elderly in China. This paper summarizes the current situation of the elderly living space and proposes the principles of aging-friendly renovation applicable to the current development situation in China, and finally proposes the strategy of living space renovation in the context of aging in place.

Feng Wang, Xiangyun Wang, Jie Liu
Experimental Study on Bending Toughness of Engineered Cementitious Composites

Through the three-point bending test of ECC, the bending toughness of ECC is studied, and the load deflection curve is obtained to evaluate the bending mechanical properties of ECC. The conclusions are as follows: after the initial crack, the load of ECC continues to rise until the ultimate load, showing good strain hardening characteristics, but the increase of deflection corresponds to the opening of a single crack, and there is no multi crack cracking; The flexural performance of ECC of ordinary cement series is better than that of ECC of composite cement series. The composite preparation of cement has a certain impact on the flexural performance of ECC. The amount of fiber has a certain influence on the flexural performance of ECC, especially the ultimate deflection. The variety of PVA fiber has little influence on the bending performance of ECC, which is generally controlled at 5%. Under the same dosage, the influence of domestic PVA fiber and imported PVA fiber on the bending performance of ECC is basically the same.

Huiqing Xue
Near-Fault Pulse Ground Motion Decomposition Based on Improved Wavelet Multi-scale Analysis Method

Near-fault pulse ground motion is a kind of special destructive ground motion. Domestic and foreign scholars usually decompose it into different frequency components in the research process. To accurately decompose the ground motion records, this paper improves the wavelet multi-scale analysis method and obtains the low-frequency and high-frequency components that can decompose the near-fault pulse-type ground motion into specific values with the boundary frequency. The effectiveness and applicability of this method are verified by time-domain and frequency-domain analysis.

Longlong Zhou, Huiguo Chen, Yixin Lei, Xiaorui Yang

Smart City

Frontmatter
A Comparative Study of Point Cloud Mapping Algorithms Towards Heterogeneous Traffic Scenarios

In recent years, the traditional automobile industry has paid an increasing attention to autonomous driving. For autonomous driving, the point cloud map contains abundant information of environment and can support various algorithms such as intelligent vehicle positioning and moving obstacle detection. Therefore, it is significant to make an accurate point cloud map for driving tasks. However, the actual road conditions are complicated in practice, especially in the underground scenes where GPS is unavailable like tunnels. Meanwhile, common point cloud mapping algorithms cannot be directly applied to long and narrow underground tunnels on the grounds that the lack of feature information, where the quality of point cloud is degenerated. Dealing with the problems above, this paper adopts a 64-line mechanical lidar and applies different point cloud mapping algorithms to construct maps, so as to explore the effect of different point cloud mapping algorithms in heterogeneous traffic scenes. The main work is as follows. Firstly, point cloud data collecting platform system has been established on a vehicle. The information interaction between the system and the environment is achieved according to the requirements of specific scenes. Then data are collected in tunnels and conventional roads, and mapped via different algorithms. Empirical validations indicate that in the scene of underground scenes which lacks of geometric structure and point cloud degradation (e.g. tunnels), Lightweight and Ground-Optimized Lidar Odometry and Mapping based on scan context (SC-LeGO-LOAM) can achieve better point cloud map over normal distribution transformation (NDT).

Jiazhong Zhang, Shuai Wang, Xiaojun Tan, Minghao Chen
Assessment of Urban Bikeability with Structural Equation Model

The concept of bikeability provides a basic framework for evaluation of cycling environment, which has great significance to promote bicycling as a low-carbon travel mode. This paper aims to propose a method for assessing urban bikeability by identifying the key characteristics influencing the willingness to use bicycle. An online questionnaire is designed for participants to score the indicators according to their cycling experiences and preferences. We adopt the structural equation model to divide the 15 indicators into five latent variables for information systemization. Based on the result, we address the relationship between the indicators and satisfaction level for cycling. Then, this paper develops an evaluation model to evaluate urban bikeability.

Yijun Liu, Aitong Pang, Gege Jiang
Long Short-Term Memory Network and Ordinary Kriging Method for Prediction of PM2.5 Concentration

When building a smart city, one must pay attention to the complex and diverse environmental problems in the city. Air quality prediction is an indispensable part of smart cities as it is conducive to guiding the development of air pollution prevention and control and alleviating urban air pollution. Based on the PM2.5 concentration data of 10 state-controlled air quality monitoring sites in Changsha City, Hunan Province, China from January 1, 2017 to December 30, 2021 and the meteorological data of Changsha city, a long short- term memory recurrent neural network model applicable to PM2.5 concentration prediction of Changsha city is formulated according to actual conditions with reference to related machine learning methods, and is used to predict the daily average concentration of PM2.5 at 10 air quality monitoring sites. Using the predicted PM2.5 concentration at the air quality monitoring sites in Changsha city, the spatial distribution simulation map of PM2.5 mass concentration within Changsha Third Ring Road is made by ordinary kriging method. Suggestions for PM2.5 pollution protection measures are put forward based on the predicted results. In addition, the interpolation analysis map of PM2.5 concentration distribution based on the measured value of each monitoring station is made. This is used to compare with the interpolation analysis map based on the predicted values so as to illustrate the rationality of the PM2.5 concentration prediction method.

Junyou Liu, Bohong Zheng, Jinyu Fan
The Influence of the Characteristics of the Elderly on the Landscape Design of Residential Area Suitable for Aging

With the continuous improvement of the age of the elderly, their psychological and physiological functions are weakening, and the demand for the use of landscape in residential areas has also changed greatly. This paper makes a detailed analysis and study of the psychological characteristics, physiological characteristics and behavioral activity rules of the elderly group, and concludes its influence on the overall planning, spatial layout, landscape facilities, construction technology and other aspects of the residential area suitable for aging garden landscape design principles and design strategies. It provides some theoretical support and design guidance for the construction of garden landscape space in line with the actual use needs of the elderly group.

Xiangyun Wang, Feng Wang
Travel Mode Recognition Using Mobile Phone Signaling Data

Urban residents can choose different travel modes, including walking, cycling, taking public transportation, and driving, and the information about the residents’ daily travel mode choices is important in the urban traffic planning and management. Therefore, the collection of such information is important. However, the traditional approaches are generally resource-consuming. Mobile phone signaling (MPS) data provides a chance to effectively collect residents’ travel mode choices. MPS data are generated when mobile phones connect to their nearby base stations. With the widely use of mobile phones, millions of MPS records are generated every day. This study explores the application of MPS data in travel mode recognition. Based on the MPS data and navigation trajectory, the proposed algorithm has four main steps: a) invalid data cleaning, b) staying point recognition, c) road matching process based on the Hidden Markov Model, and d) trajectory similarity calculation based on the Dynamic Time Warping. An Experiment is preformed to test the applicability of the proposed algorithm.

Fanghao Fu, Jiemin Xie, Shuqi Zhong, Ming Cai
Construction and Study of Automotive Working Conditions Based on Improved K_means Clustering

To address the problem that the random selection of the initial clustering centers when using K-means clustering for the construction of working conditions cannot guarantee the quality and stability of clustering, a method of selecting the initial clustering centers based on the data's own characteristics is proposed. Taking the actual operating conditions of passenger cars in Zhengzhou city as the research object, a processing method combining short-trip division of test data, principal component analysis (PCA) and improved K_means clustering is realized by using MATLAB programming to construct the cyclic working conditions of passenger cars in Zhengzhou city. The results of the comparison with the typical working conditions constructed by traditional K_means clustering show that the error of the characteristic parameters of the working conditions constructed by the improved K_means clustering has been reduced, and the average error of the joint velocity-acceleration distribution and the actual full working conditions has been reduced from 0.55 to 0.43, which is a 21.8% improvement and proves the effectiveness of the improvement, and the accuracy of the constructed working conditions is higher and more comprehensive to reflect the actual traffic conditions in Zhengzhou. The accuracy of the constructed conditions is higher, which can reflect the actual traffic conditions of Zhengzhou city.

Wei Ding, Songwen Tian
Research on the Innovative Design Mode of Guangzhou Vernacular Architecture Under the Background of Carbon Neutrality

Carbon neutrality is an important topic of environmental economics, and it is also an important strategy to promote the development of low-carbon buildings. The article takes an eco-leisure guesthouse next to the Art Town of Zinitang, Panyu, Guangzhou as a practical case, and studies the honeycomb paper calcium silicate board produced by construction users as the wall material, which is fully integrated into the design. Finally, it provides reference for the low-carbon design mode of modern vernacular architecture in Guangzhou.

Qiang Tang, Yile Chen, Liang Zheng, Junzhang Chen
The Thermal Comfort Characteristics of PCS Applied in EVs

In order to satisfy the needs of occupant’s thermal comfort and reduction in HVAC energy consumption at the same time, based on the thermal comfort improvement measures in the building environment, this research applies the personal comfort system (PCS) to the electric vehicle cabin. By testing the physiological and psychological parameters of the occupants at different ambient temperatures, the effect of different local heating methods on the thermal comfort of the occupants is studied. The results show that PCS can effectively both increase the occupant’s body surface temperature and the local and overall thermal sensation. In addition, the thermal sensation of the feet has the largest influence on the overall thermal sensation with the separate heating method which will provide a reference for the winter heating design of the EV in the future.

Jingjing Wu, Jingde Zhao
Mode Choice Behavior of Ride-Sourcing Passengers Under Travel Time Variability

Travel time variability has a great impact on travel behavior. In this paper, we conduct a survey which shows that travel time variability is a vital element of mode choice in ride-sourcing services. According to the survey results, we address some key factors that influence travelers’ mode choices, including travel time, travel time variability, monetary cost and comfort. Then we propose a theoretical framework to investigate the mode choice behavior under travel time variability. In addition, the pricing strategy of the ride-sourcing company is formulated as an optimization problem. Our study shows that considering the impact of travel time variability is of vital importance both in modeling the travel behavior of travelers and the pricing strategy of the ride-sourcing market.

Aitong Pang, Xin Zhang, Gege Jiang
Intelligent Control of Shield Tunneling from the Perspective of Complex Network

In order to more comprehensively analyze the influence of shield tunneling parameters on shield machine performance, this study develops a complex network (CN) -enabled framework to explore the shield tunneling performance. In the first step, Principal Component Analysis (PCA) is used to observe time series data. In the second step, the adjacency matrix is obtained by calculating the correlation between parameters of any two rings and setting appropriate threshold values. Each node of the complex network stands for different rings, and the links between nodes (i.e. edges) represent the nonlinear relations between the rings. Finally, Leiden, as an excellent community discovery algorithm, aggregates nodes with similar tunneling status to form clusters of different sizes in the network, and different clusters show different tunneling performance in terms of over excavation rate. We verify the feasibility of complex network theory in the case study about the Contract T308 along the Eastern Regional Line (ERL) in Singapore.

Xiaojing Zhou, Yue Pan, Jianjun Qin
A Systematic Review of Urban Design and Computer Modelling Methods to Support Smart City Development in a Post-COVID Era

The COVID-19 pandemic emphasised the need for decision-support tools to assist urban designers in building resilient and smart cities. Therefore, a multi-disciplinary systematic review was conducted following the PRISMA guideline to identify papers relevant for selecting appropriate methodologies that can be applied to build decision-support tools for resilient cities. This paper presents a list of 109 key references, selected from 8,737 records found from the searches, and identified major research themes, fundamental design interventions, and computer modelling techniques. We extracted six groups of interventions categorised by different scales of action: from an individual, crowds (social distancing and travel-related interventions), to a building, a neighbourhood/district, and a city. In addition, there are three sorts of computational modelling approaches, i.e., computer simulation, statistical models, and AI algorithms. Most of the studies developed models for predictive purposes, and 28% of the modelling studies built models for descriptive purposes. This work intends to empower urban designers and planners to overcome and get prepared for unpredictable disasters in pursuit of resilient and smart cities, particularly in the post-pandemic world. This review enables them to quickly find relevant papers as well as suitable methodologies and tools for a particular research purpose.

Liu Yang, Michiyo Iwami, Yishan Chen, Mingbo Wu, Koen H. van Dam
Impact Estimation of Traffic Accident Duration Based on Survival Analysis by Using Field Urban Traffic Condition

Analyzing and predicting accident duration is important in the field of Traffic Incident Management (TIM). This study imports survival analysis to identify the influencing factors for the duration of urban arterial-way accidents based on field accident data and traffic condition data. First, the Kaplan-Meier method is used to compare the accident duration distributions under different attribute values. And then, the Cox proportional hazard model is developed to investigate the relationship between accident duration and different attributes. Finally, the analysis result shows that the impacted duration of nighttime accidents and off-rush time accidents is significantly longer than that of daytime accidents and rush-hour accidents, and the arrival time of TIM staff and accident location significantly influence the risk of accident ending. The proposed model can help accident clearance operators investigate urban traffic accident duration and make real-time management strategies.

Duanya Lyu, Yongjie Lin
An Integrated Framework for Population Synthesis at Fine-Grained Spatial Scales

With the conception and development of Smart City and its applications, Digital Twins and other related technologies have been growing rapidly during the past years. Simultaneously, in the fields of transportation and urban analytics, agent-based models (ABMs) and microsimulations have also gained popularity, partly echoing the Digital Twins initiatives in Smart City applications, and is also owing to the sharply rising utilizability of high-performance computation resources and rapidly boosting high scale data storage. This study mainly developed a population synthesis pipeline to generate spatially detailed populations in urban environments and combined probabilistic models and re-weighting techniques for agent synthesis to cope with microdata on heterogeneity and marginal control matching. We also structured the built environment with higher spatial resolution than previous studies. We then created a realistic and spatially fine-grained synthetic population by the assignment of agents to the spatial units via rule-based and behavioral modeling. The results show good performance in terms of the accuracies over different dimensions and the proposed pipeline can facilitate the use of ABMs in Smart City projects.

Yinni Huang, Meng Zhou, Runqin Deng, Zeteng Huang, Linlin You
Backmatter
Metadata
Title
Proceedings of the 2022 International Conference on Green Building, Civil Engineering and Smart City
Editors
Wei Guo
Kai Qian
Copyright Year
2023
Publisher
Springer Nature Singapore
Electronic ISBN
978-981-19-5217-3
Print ISBN
978-981-19-5216-6
DOI
https://doi.org/10.1007/978-981-19-5217-3