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Über dieses Buch

This volume comprises select peer reviewed papers presented at the international conference - Advanced Research and Innovations in Civil Engineering (ARICE 2019). It brings together a wide variety of innovative topics and current developments in various branches of civil engineering. Some of the major topics covered include structural engineering, water resources engineering, transportation engineering, geotechnical engineering, environmental engineering, and remote sensing. The book also looks at emerging topics such as green building technologies, zero-energy buildings, smart materials, and intelligent transportation systems. Given its contents, the book will prove useful to students, researchers, and professionals working in the field of civil engineering.

Inhaltsverzeichnis

Frontmatter

Unexpected Cracking in an RC Bridge Pier Cap—A Case Study

This paper presents an investigation on structural cracking observed in a reinforced concrete (RC) pier cap supporting a prestressed concrete box girder of 13 m span. Unexpected vertical cracks were observed at service loads on the sides directly under the bearings. A site visit revealed that the elastomeric bearings were compressed on one side with loss of contact on the other. The crack width measurements showed a crack width as high as 1 mm at some locations, where the cover provided was found to be 100 mm, more than the proposed cover of 50 mm. A detailed analysis using non-linear finite element analysis (NLFEA) established the reason for cracking as the reduced contact area at the bearings. The wide cracks were due to the unexpected high cover. The safety of the structure at ultimate loads was also checked using NLFEA and the strut and tie method, and is seen that the structure is safe at ultimate loads.

Indu Geevar, D. Adrija, Devdas Menon, A. Meher Prasad

Flood Inundation Mapping of Cauvery River Using HEC-RAS and GIS

Flood is a natural disaster and causes loss of life and property destruction. The objective of the study is to prepare a flood inundation map for a stretch of the river Cauvery for different return periods. To perform hydraulic modelling, the software HEC-RAS was used. GIS was used for spatial data processing and HEC-GeoRAS for interfacing between HEC-RAS and GIS. The obtained inundation map shows total submergence of areas nearby along the chosen stretch, highlighting the need for an adequate flood warning system and proper flood protection works along the stretch. These in conjunction with proper land use management and afforestation can significantly reduce the adverse effects of flooding, particularly in the low-lying areas. Results of such studies will help the departments and agencies concerned to formulate appropriate strategies for mitigating the flood hazard in the river basin.

Abhijith Sathya, Santosh G. Thampi

The Potential Use of Biopolymers as a Sustainable Alternative for Liquefaction Mitigation—A Review

Saturated cohesionless soils, when subjected to sudden loads like earthquake, will exhibit a phenomenon called liquefaction and start behaving like a liquid. This is due to the sudden build-up of excess pore water pressure that results in the complete loss of shear strength. Most of the traditional liquefaction mitigation approaches have several limitations like high cost and labour, disturbance to existing structures and other environmental issues. This paper reviews a series of researches that involve contemporary liquefaction mitigation practices and their mechanisms. It also presents a concise review of the application of bio-geotechnical methods for soil improvement, focusing on the use of biopolymers. Biopolymers are of biological origin and are environmentally friendly. They consist of repeating monomeric units bonded together to form a long polymeric chain and they are used commonly in the chemical as well as the food industry. In the past decade, numerous researches have been carried out to demonstrate their use in the field of geotechnical engineering to improve the various properties of soil. Biopolymers like xanthan, agar, guar, chitosan and starch were found to improve soil properties such as shear strength, permeability and compressibility significantly. Thus, biopolymers could be used to create engineered soil with modified properties in this epoch of depleting natural resources. Findings from the review of works of the literature indicate the prospective use of biopolymers as a sustainable substitute for preventing soil failure due to liquefaction in view of their pore filling and shear strength enhancement properties. Furthermore, the need for exhaustive research on the proposed concept is suggested.

S. Smitha, K. Rangaswamy

Analysis and Mitigation of Delay in Construction of Multistoried Building

Any constructional project success can be realized by achieving its objectives within the planned time, budget and level of quality. One of the major problems that face the construction projects is being behind the schedule. Hence, there is a need to analyse the delays in the construction process followed by the mitigation process. This study focuses on the factor that causes a delay in the construction of multistoried residential buildings located in Kerala, India. The methodology adopted comprises data collection and analysis. Data collected include project type, duration of each activity, planned schedule and actual schedule. Time overrun of each activity was calculated, using this data. Duration Index and Delay Index was proposed and used to determine the critical activities. Delay prediction model was developed by considering its significant variables. The results from the prediction model revealed that the foundation, painting and masonry are the most influencing activities that contribute to the delay in the construction of a multistoried building. A questionnaire was developed in order to evaluate the cause of the delay in each activity. Data were gathered through the survey, ranked using Likert scale and relative importance index (RII) was found. Significant causes of delay and their severities on each activity were identified using RII. Response from the questionnaire survey concludes that the inadequacy of material and labour resources is the prominent cause of the delay in construction. This study paves a way in the construction engineering field to mitigate, analyse and overcome the overall delay in the construction of multistoried buildings.

C. P. Muneera, K. J. Joe Maria

Behaviour of Concrete-Filled Fibre Tubes Under Axial Compression and Lateral Loading

The steel reinforcement in the infrastructures throughout the world undergoes corrosion and it leads to the need for a new product, to those involved with reinforced concrete structures. Concrete-filled fibre-reinforced tubes (CFFT) are formed by combining the concrete and the fibre-reinforced polymer (FRP) sheets with epoxy in which concrete is filled in the prebuilt FRP tube. CFFT columns can be effectively used for earthquake resistant designs, because the lateral confinement increases the ultimate axial strain and compressive strength of concrete (Ozbakkaloglu and Oehlers in Journal of Composites for Construction, 12:469–477, 2008). This work mainly deals with the performance of CFFT and conventional columns under combined axial compression and lateral loading using Ansys workbench. The objectives of this study were to compare the seismic action of conventional columns with CFFT columns using different FRPs such as carbon, glass and aramid, and CFFT columns using different FRP rods made of carbon, glass and aramid fibres. An experimental study was also conducted to validate the material properties of fibres which were used in the seismic study of columns. The compressive strength of ordinary concrete cylinders, concrete-filled glass fibre tube cylinders and concrete-filled carbon fibre tube cylinders were found out. The test results revealed that CFFT columns can produce huge inelastic deformation capacities under seismic loading.

N. Athira, Liji Anna Mathew, U. K. Neeraj

Experimental Investigation of Coir Fibre on Its Potential for the Sorption of Hydrocarbons

Groundwater contamination due to petroleum hydrocarbons is a common problem worldwide. It occurs due to surface oil spills or leaking from underground storages. Nowadays, it becomes a threat to the quality of drinking water wells also. The field remediation methods usually practised involve treating the water by pumping out of the well and recharging it. In this study, an environmentally friendly sustainable solution using coir geotextile is proposed to suggest a remedial measure against hydrocarbon contamination. Hence, it should possess the capability to sorb the contaminants so that its migration towards the groundwater is controlled/arrested. This study aims to analyse the adsorption behaviour, degradation effect, surface morphology and the variation in the lignin-cellulose content of coir geotextile under the action of hydrocarbons. The experimental results exhibit better sorption capacity of oil by coir fibres. Moreover, it is observed that the degradation behaviour is not much influenced by the action of hydrocarbons.

A. V. Praseeja, N. Sajikumar

Dynamic Phase Lag Studies of Damper Mounted Substation Structures

Stability and safety of fragile equipment used in electric power applications are in demand against strong ground motions. Post-earthquake data necessitates the seismic studies on substation used porcelain components in evident to the poor serviceability of the equipment. The installed structures that failed at the field are experimentally tested and passed in laboratories under real-time earthquake motions. In addition to that, with the influence of the heavy movement of tectonic plates, the site-specific conditions are varying rapidly and consequently resulting in the progression of structural failure. Therefore, mitigating the vibration at the base level of the supporting structure is one possible solution to the undesirable ground accelerations. In this paper, two current transformers of different ratings supported on steel structure are considered and evaluated for response phase when subjected to site specified accelerations at critical frequencies with the help of experimental damping factor. Also, the structure is studied for viscoelastic damper attached at the base to recognize the phase shift with the specified ground accelerations. In both the cases of the structure with and without the damper, the system damping is extracted from shake table experiments of 0.3 g ground acceleration. Conclusions are derived for the model connected with damper during complete earthquake vibration using angles of phase versus frequency ratios. The results may be used in redesigning the structure prior to the standard recommended testing.

N. Srujana, T. Bhavani

Acoustic Emission Characteristics of Cementitious Materials During Early Age Hydration

Acoustic Emission (AE) testing was used to study the hydration process in cementitious materials during the first 18 h of setting. AE activity was monitored in fresh cement paste, mortar and concrete specimens. The specimens had a different mixture of composition. It was observed that the AE activity depended on the size of the aggregate present in the cementitious mixture. More AE signals were recorded during the setting process in specimens with the lower w/c ratio than for the higher one. Specimen cast with cement paste showed more AE activity compared to the larger coarse aggregate size (20 mm). The AE activity in fresh concrete is accredited to cavitation in the pores of cement paste during the hydration process and shrinkage. The AE activity showed a notable trend during the time of setting, based on which it was divided into three stages namely, before hydration, partial hydration and complete hydration. The occurrence and duration of these stages varied for cement paste, mortar and concrete. In this study, it was observed that if more AE signals are recorded during the hydration process, higher will be the strength gained by the same concrete in-situ.

Injila Hamid, Umair Ali Wani, Shafat Farooq, Aditya Sharma, R. Vidya Sagar

The Suitability of Marine Clay–Zeolite Mix as Landfill Liners

Feasibility of using marine clay modified with zeolite for the construction of landfill liner was studied. Compacted natural clays are commonly used as liner material due to their high containment, attenuation and cost-effectiveness. The material chosen for liner construction has to satisfy the standards set by Environmental Protection Agency (EPA), based on plasticity characteristics, hydraulic conductivity and shear strength. As per EPA standards, the hydraulic conductivity of the liner material should be less than 1 × 10–7 cm/sec. The feasibility of using marine clay–zeolite mixtures as landfill liner material is presented in this study, and the most acceptable zone was obtained for the same. The liner material was prepared by mixing marine clay with various percentages of zeolite (0–25%). Initially, the suitability of moist and sun-dried marine clay was assessed, because marine clay exhibits different index properties in the natural moist condition and dried condition. Experimental programme involved laboratory tests to determine the index properties, compaction characteristics, hydraulic conductivity and shear strength of marine clay and marine clay–zeolite mix. In order to study the strength development, samples were kept for curing for 7 days, 28 days and 3 months. From the results, 15–20% zeolite content in sun-dried marine clay was found to be optimum.

Krishna Santhosh, G. Sanoop, Sobha Cyrus, Benny Mathews Abraham

Ductility Assessment of an RC Section

Ductility is considered to be an important ability of a material to undergo appreciable plastic deformations before the collapse, and therefore, it is a crucial factor for earthquake resistant design of reinforced concrete sections. Ductility depends upon reinforcement detailing describing the confining of an RC section and engineering properties of constituent materials apart from the structural configuration. The member ductility is generally defined in terms of strain ductility, curvature ductility, and rotational ductility, while safety is assessed through the overstrength factor. The grades of reinforcing steel specified in IS 1786–2008 also include an additional classification for improved material ductility. In the present study, the curvature ductility, plastic rotation capacity, and overstrength factor of an RC column section are evaluated to assess analytically the variation in ductility and safety with a varying spacing of confining steel using ductility-based grades of confining steel having characteristic yield strength as 500 N/mm2. The confining steel used is Fe 500, Fe 500D, and Fe 500S. The effect of confinement has been considered applying Mander’s model. It has been observed that the curvature ductility, plastic rotation capacity, and overstrength factor decrease with an increase in spacing of confinement steel. However, the reverse trend has been observed with reference to the diameter of confinement bars.

Kshama Hemkar, Laxmi Kant Mishra, Goutam Ghosh

Finite Element Analysis of Shape Memory Alloy Ring Spring System for Steel Frames

Shape Memory alloys (SMAs) are smart materials that are capable of recovering its shape under unloading. This phenomenon is mainly due to its two unique properties such as shape memory effect (SME) and superelasticity (SE). The post-earthquake damages suffered by traditional steel frames can be mitigated by the SMA ring spring system in beam-column junctions. An SMA ring spring system is a combination of an inner ring of high strength alloy enclosing an outer ring, made of shape memory alloy with tapered faces. The force generated due to the wedging action between the HSS inner ring and SMA outer ring is responsible for resisting the external loads. This paper deals with the potentiality of the SMA ring spring system in steel frames for seismic applications. A nonlinear finite element analysis using ABAQUS is carried out to study the response of the SMA ring spring system under cyclic loading. For the SMA outer ring, a user-defined material model based on Auricchio's approach is used for expressing the superelastic behavior of SMA. A kinematic hardening model with von Mises yield criterion was used for evaluating steel material. A global analysis of a 3D multi-story frame is carried out to identify the most critical beam-column in the frame under seismic loading. Subsequently, the critical beam-column junction is modified with the SMA ring spring system. A dynamic implicit acceleration was given to the steel beam. The proposed connection shows a superior hysteresis loop and self-centering ability with a substantial increase in the load carrying capacity of the connection.

Ashwin Jose, C Prabha

The Development and Study of Fiber Reinforced Fly Ash Bricks

Knowledge of the importance of environmental sustainability and overexploitation of nonrenewable resources in the field of civil engineering has brought tremendous growth in the research and development of various construction materials. One such alternate material is fly ash which is produced from the thermal industries as a waste material. Manufacturing of traditional clay bricks involves the extraction of high amounts of clay and also the removal of topsoil from the soil surface. Usage of such waste by-products extracted from various industries in the place of conventional construction materials is a forward step to reduce the substantial depletion of natural resources. The addition of fibers to concrete has proven to give higher results in terms of Mechanical Properties like compressive strength, flexural strength, etc. Similarly, one such development in bricks by adding fibers might bring higher performance and strength values. Since bricks are one of the basic components in the construction industry, they tend to bear bending loads in case of load-bearing walls and also are susceptible to Cracks. Hence parameters like compressive strength and durability of bricks alter the performance of walls. This paper shows the experimental program on properties like compressive strength, water absorption, and durability of fly ash bricks induced with different fibers like glass fibers and coconut coir in 1 and 2% (by weight of Fly ash). The composition of fiber reinforced fly ash bricks was 60% of fly ash, 10% of ordinary portland cement (OPC), and 30% of quarry dust. The Compressive strength of fiber reinforced fly ash bricks for 7 and 28 days, respectively, along with water absorption, impact resistance, and efflorescence are determined.

P. Prathyusha, Kolli Ramujee

Seepage Behavior of Fiber Reinforced Embankment Fill: A Review

The earth structures like river embankments, levees, canal diversion structures, check dams, etc., have an important role in the irrigation and drainage projects. Construction of these earthen embankments with satisfying strength and stability requirements is a major challenge for the geotechnical engineers. One of the main reasons for the failure of the earthen structures is the piping erosion due to the seepage force from the water reservoir in the upstream side. Piping resistance of the embankment fill material is a major parameter that influences the stability of the structure, hence proper treatment is to be given to the fill material to enhance the seepage and piping resistance. The fiber reinforcement is one of the widely accepted methods of ground improvement. There are some studies that are focused on the seepage behavior of embankment made with fiber reinforced soil. The main aim of this paper is to review the possible applications of fiber reinforced soil as fill material for earth embankment which is more susceptible to seepage failures. With reference to the previous studies, a critical comparison is done in this paper to evaluate the relative importance of different parameters on the behavior of fiber reinforced embankment fill.

V. P. Devipriya, S. Chandrakaran, K. Rangaswamy

Ground Improvement with Stone Columns–A Review

Soil improvement is rapidly gaining importance due to the paucity of good quality land for development, structures, and transportation infrastructures. A range of soil improvement methods is available amongst which stone column is one of the most efficient and effective techniques. It is generally used to improve soft and weak soil, having less bearing capacity, high compressibility, and high settlement. The improvement is due to its higher stiffness compared to the surrounding ground, and it is measured in terms of stiffness improvement factor. The stone column is designed as per IS 15284-2003 and is usually analyzed by using the unit cell concept. They are generally constructed using crushed stone aggregates and are ideally installed in an equilateral triangle pattern. The failure of the stone column is dependent on its critical length. This review paper is aimed to study some exemplary practices done while designing, constructing, or installing the columns. It also intends to analyze the effects of these practices, which include the pros and cons of each method. Some modifications include geotextile or geosynthetic-encased stone columns, rubber-drained columns, lime-fly ash columns, lime-mortar soil columns, and a column for liquefaction mitigation. Hence, it aims to access the suitability of these practices in the coming future to have increased effectiveness and overall efficiency. Further, some suggestions are made regarding the construction practices which may be pertinent in the near future.

Revathy Manohar, Satyajit Patel

Effect of Fly Ash on Geotechnical Properties of Oil-Contaminated Soil

Accidental oil spillage or leaking has caused severe damage to the environment. Oil contamination can adversely affect the soil microbes and plant as well as contaminate groundwater resources for drinking or agriculture. Hydrocarbon contamination will not just affect the quality of the soil but will also alter the physical properties of oil-contaminated soil, excessive settlement of tanks and breakage of pipeline. Contamination changes the behaviour of soil and also alters its engineering properties leading to several problems like loss in strength, differential settlement and cracks in existing foundation or structure. For any possible applications of contaminated soils, knowledge of the geotechnical behaviour of contaminated soil is required. The experimental programme was carried out in the present study to know the effect of diesel oil contamination (4, 8 and 12%, by dry weight) on geotechnical properties of locally available fine-grained soil and the efficacy of fly ash as a stabilizing agent at different percentages 20, 40 and 60% (w/w). The results show that the consistency limits and the strength parameters have been affected marginally due to contamination. The utilization of industrial by-products such as fly ash is of increasing importance as an option for stabilizing contaminated sites due to its pozzolanic nature and also in view of minimizing the environmental impact. The plasticity index of stabilized soil was observed to be not uniform with the increase in fly ash addition. The compaction characteristics, Unconfined Compressive Strength (UCS) and CBR value of soil decreased with the addition of contaminant and it regains marginally with the addition of fly ash. UCS and CBR values showed an increase of 29.5 and 73.5% with an addition of 60% fly ash. The results from the study may be beneficial for the engineers and researchers in reusing the contaminated soils for safe and economic construction of structures.

Veena Jayakrishnan, Aiswarya Gracious, Anila C. Shaju

Development of Pavement Performance Prediction Models for Low-Volume Roads Using Functional Characteristics

Pavement evaluations are done to determine the functional and structural conditions of the pavement. The combined action of age, traffic, climate and environmental factors usually affects the surface course and causes functional deterioration of the pavement. This will adversely affect the riding quality as well as the vehicle operating cost. The present study aims in developing pavement performance prediction models for low-volume roads in Calicut district of Kerala state, India. The roads considered for the study have an age varying from 1 to 7 years. The data determining the present conditions of the pavement such as pavement distress data, roughness, skid resistance, texture depth, traffic data and geometric details were collected. Since the pavement condition also depends on the subgrade conditions, California Bearing Ratio (CBR) and maximum dry density of subgrade were also collected. The Pavement Condition Index (PCI) and International Roughness Index (IRI) were calculated from the distress data and roughness data, respectively. Three different models were developed to predict the PCI, IRI and Skid Number (SN) of the road sections. Multiple regression models developed correlates PCI, IRI and SN with different factors such as age, Average Daily Traffic (ADT), texture depth and CBR. The performance of each model developed was evaluated using selected performance criteria. The models so developed help the concerned authorities in making decisions on the maintenance strategies as well as the allocation of funds.

Muhammed Shibil P, M. Sivakumar, M. V. L. R. Anjeneyulu

Design and Analysis of Diagrid Structural Systems for High-Rise Buildings

The diagrid is a framework of diagonally intersecting members that are used in the construction of buildings and roofs. It requires a lower percentage of steel than a standard design. The need for columns and can be obviated by the use of diagrids. Diagonal members in the system carry gravity loads as well as lateral forces. Due to the triangulated configuration of members, internal axial forces arise in the members, in turn minimizing shear racking effects. Diagrid structures are generally used in the construction of high-rise buildings as lateral forces get minimized. The primary goal of the research is the design and analysis of diagrid structural systems for the high-rise buildings. The modeling was done by using PATRAN software and was analyzed using NASTRAN software. The study includes analysis of the representative models of various geometric forms for optimal construction in terms of strength, stiffness, aesthetic appearance, material requirement, and low cost. The investigations also include the study of the optimal cross section of diagrid members. A quasi-static environment and geometric nonlinear analysis are considered in the analysis of diagrid structures.

Sneha Mole Jacob, N. Phani Charan, Anju Raju

Seismic Analysis of Composite Box Girders with Corrugated Steel Webs and Trusses

The concrete box girder is one of the most commonly used bridge structures due to its large flexural and torsional stiffness. For long spans, this will not be applicable since it increases the self-weight of the structure. To reduce the self-weight, steel–concrete composite bridges had been introduced. These steels have the potential to produce considerable weight savings, although a hindrance to their effective use in conventional stiffened flat web plate girders includes the potential for web instability, excessive deflections, and fatigue failure. To overcome the limitations, innovative designs have been proposed, including the use of corrugated webs to provide enhanced shear stability and eliminate the need for transverse stiffeners. This structure consists of a top concrete slab, corrugated steel webs, and two bottom concrete-filled steel tubes connected by trusses. The project work firstly studies the behavior of a pedestrian bridge and then continues with a road bridge and its seismic analysis using FEAST (Finite Element Analysis of Structures) software. The response spectrum method of analysis is used to evaluate the maximum deformation, and stress. Various parameters used for the study are thickness and diameter of concrete-filled steel tubes (CFST), corrugated web height, and corrugation length. A comparison between flat plate web and corrugated web is studied to confirm the efficiency of corrugated webs.

P. Aparna, Binol Varghese

Experimental Study on the Effect of Natural Rubber Latex and Plastic Fiber in Concrete

In the modern construction industry, there are a lot of materials introduced for enhancing the properties of concrete. Natural Rubber Latex (NRL) is polymer latex obtained from renewable and locally available resources, which can be employed for the effective modification of cement composites thereby encouraging a sustainable construction practice. The Natural Rubber Latex modification significantly improves the plain concrete from porous to an impermeable and denser microstructure by forming a lining of latex film across voids, pores, and micro-cracks. Polyethylene Terephthalate (PET) is a polyester polymer obtained from recyclable bottles. This project work investigates the combined effect of rubber latex and PET fibers in M40 grade concrete. Various tests are conducted on the laboratory cast concrete specimens and their behaviors are observed and documented for 7 days and 28 days testing. The solution offered in the project by using waste plastic is one of the answers to the long-standing menace of waste disposal.

Elizabath M. John, Seethu Sunny

Effects of Eggshell Powder and Granite Powder on the Strength Properties of Concrete by Partial Replacement of Cement and Fine Aggregate

In construction industries, the usage of cement and fine aggregate gets increased rapidly. Due to the increasing demand and higher cost of cement and fine aggregate, cement is partially replaced by eggshell powder and fine aggregate by granite powder. Eggshell waste is evolved from poultry farms, restaurants and hotels and is made up of calcium which is very similar to cement. Calcium in concrete causes a substantial increase in strength and acts as an accelerator. Granite powder is obtained from granite industries while cutting huge rocks to the desired shape. The disposal of granite powder on land causes environmental hazards like air pollution. In this project, the effect of varying percentages of eggshell powder by the weight of cement and granite powder by the weight of fine aggregate is investigated without changing the mix M40. By utilizing the waste materials, specimens are cast and various tests are conducted such as compressive strength, split tensile strength, flexural strength. The behaviors of the concrete specimen are observed and compared with conventional concrete after 7 and 28 days testing.

Geethika G. Pillai, Manjusha Mathew

Comparison of Seismic Response of a Multi-storied Building With and Without Liquid Damper

A tuned liquid damper is liquid confined in a container usually placed on top of a building that uses sloshing energy of water to reduce the dynamic response of the system when it is subjected to excitation. Usually, liquid dampers are strictly connected to the main structure. The seismic analysis, also known as pushover analysis, is a subset of structural analysis. It is the calculation of the response of a building structure to earthquakes. It helps in identifying critical members to reach limit states during the earthquake and hence proper attention can be given while designing and detailing. In this study, a comparison of the seismic response of a multi-storied building with and without liquid damper will be studied. Also, a comparison of various liquid dampers will be checked and various parameters like lateral displacement, storey drift, etc., will be studied for the building. Suitability of different liquids was also studied. The software selected for the analysis is SAP2000.

Arsha A. Deleep, Varsha Susan Thomas

Enhancement in the Load-Carrying Capacity of RC Rectangular Columns Adopting CFRP and GFRP

There exist various techniques for retrofitting of reinforced concrete structural elements that have undergone damage. The use of FRP wrapping is one of the retrofitting techniques to enhance the load-carrying capacity of reinforced concrete (RC) columns (up to 20% increase). In this work, enhancement of axial load-carrying capacity of distressed RC columns adopting CFRP and GFRP was carried out. An RC column having a cross-sectional dimension of 400 mm × 600 mm and a height of 4 m is considered for this study. The RC column considered for the study was initially designed using concrete having a compressive strength of 30 N/mm2. Eventually, due to erroneous mixing and placing of concrete in the site, it resulted in the concrete in the column to have developed a lower compressive strength of 25 N/mm2. This distressed RC column eventually tends to have a lower load-carrying capacity due to a reduction in the compressive strength of concrete. This RC column is retrofitted using fibre-reinforced polymer (FRP) composites by wrapping the column to restore its original load-carrying capacity through the confinement provided by the FRP wrapping. The FRP composites considered in this study are carbon fibre-reinforced polymer (CFRP) and glass fibre-reinforced polymer (GFRP) fabrics wrapped around the distressed RC column with the application of epoxy. The design and estimation of quantity of the retrofit using CFRP and GFRP are adopted based on ACI codal provisions (ACI 440.2R-08). It was learnt by carrying out the design of the retrofit for the distressed RC column, the number of CFRP and GFRP layers obtained for wrapping are five numbers and ten numbers, respectively. From this study, it is learnt that CFRP is better when compared to GFRP in terms of enhancement in strength and load-carrying capacity of the distressed RC column with a lesser number of layers of wrap.

Md Ibrahim, Y. K. Guruprasad

Efficiency Assessment of RC Jacket Applied on a Distressed RC Column Using Different Codal Provisions

Reinforced structural elements undergo damage when they are subjected to external agencies such as earthquakes, exposure to fire and ageing due to environmental factors. When important reinforced concrete (RC) structures undergo damage that is within a repairable limit, repair or retrofit strategies are adopted to restore the strength, stiffness and stability of such damaged buildings. In this work, an RC column is considered having the dimensions 250 mm × 500 mm × 3200 mm. The RC column in this study is cast with concrete having a compressive strength of 18 N/mm2. The distress in this case is in the form of low compressive strength of concrete leading to low load-carrying capacity. Due to this reason, a strength modification of the concrete compressive strength in the RC column is required to enhance the load-carrying capacity. In this case, the RC column is retrofitted with the external application of reinforced concrete (RC) jacket around it. The RC jacket retrofitting method is applied when the increase in the load-carrying capacity to be enhanced is more than 25%. The reinforced concrete jacketing which is to be provided around the distressed RC column is designed by Indian codal provisions (IS 15988: 2013) and ACI codal provisions (ACI 318: 2008) separately. The design parameters provided and obtained using these codes are compared. From this study, the optimum thickness of the RC jacket applied is also evaluated. The Indian codal provision takes into account an upper bound while considering the factor of safety for design and leading to the overestimation of design parameters and quantities. The effectiveness of design with respect to the strength can be achieved by considering the optimum requirement of the quantities as per ACI codal provisions such that the cost of the overall retrofit can be minimized.

Mazharuddin Mohammed, Y. K. Guruprasad

A Feasibility Study of Colloidal Silica as Stabilizing Material for Passive Site Remediation

Passive site stabilization is a ground improvement method that causes minimal disruption to the site being treated. The concept is to allow a low-viscosity fluid to flow to the target area that solidifies there and create a bond between soil particles. Colloidal silica can be used as a stabilizing material in passive site remediation. This paper explores the chemical processes that are required to initiate the gelling process in colloidal silica. pH and ionic strength are the two parameters that most affect the gelation of colloidal silica. The paper aims to explore optimum pH and corresponding salt content which provide workable gel time in the field. Gel time has been observed for a maximum of 120 days at different pHs and, gel time curves are plotted for various combinations. It was found that increasing salt content leads to a decrease in the gel time. A pH range of 4.5–6.2 has been observed as the most optimum pH range. To find out the effects of gelation in the sand, unconfined compression tests were performed. Samples of 40% relative density grouted with four different colloidal silica percentages under a curing period of 3, 7 and 28 days were tested. A total of 36 samples was tested. It was found out that the strength of the treated sand increases with an increase in colloidal silica percentage and curing time. As a result of the findings of the present research, colloidal silica can be proposed as a suitable stabilizer for non-disruptive liquefaction mitigation.

Prashansha Sharma, Jiji Krishnan, Shruti Shukla

A Critical Review on Mass Concrete Embedded Water Pipes as Permanent Roofing

Tumbling the external energy demand of buildings has always been a challenge for researchers around the world. Supply–demand statistics has never dipped the cost of energy and has always compelled researchers to come with newer models and methods. These methods often lead to huge initial investment and tough maintenance schedules. Concrete, a roofing material in many countries has an excellent thermal mass and can be a source of energy. This when used in roofing structures with water pipes embedded running through it will decrease the external energy demand and maintain comfort conditions inside the building. Studies conducted in this area, even though smaller in number, have been thoroughly reviewed. Different studies conducted in this area, such as the use of PCM (Phase-Change Materials), roof integrated solar heaters, solar concrete collectors, and embedded pipes, removal of hydration heat of concrete, have been analyzed. It was evident that the work in the direction of the solar concrete collector which picked acceleration in the 1990s and early 2000s then gradually gave way for the use of PCM in roof’s concrete collector which was later found to be a failure by itself. Reviews conducted in this article point towards a very serious need for ongoing research in the area of mass concrete embedded water pipes as a permanent roof for achieving energy-efficient residential buildings. Heat extracted by water can then be used to meet different energy-consuming demands of the building itself like hot water for building’s hot water needs, coupling it with thermal power units, solar absorption refrigeration system or even a simple solar stills to produce potable water.

V. P. Jai Shankar, V. K. Jebasingh

Rock Mass Rating and Geological Strength Index Relationship for Sandstone Along Rock Cut Slope at Markundi, Chopan, District Sonbhadra (U.P.)

The Rock Mass Rating (RMRb) and Geological Strength Index (GSI) are widely employed in geotechnical engineering practice. An attempt has been made to analyze the RMRb and GSI using in situ data corresponding to sandstone rock collected from different outcrops in Markundi Hill along SH-5, Chopan, Sonbhadra. RMR and GSI have been analyzed in order to compare them with the results of the analysis conducted in this study. The Markundi Sandstone is categorized Poor rock mass and Fair rock mass at the locations from the data collected on the basis of RMRb. Finally, the best (most suitable) applied math relations between RMRb and GSI are shown and they are accustomed establish general correlations. Hoek (2013) generalized equation show the best regression relationship between RMRb and GSI for Markundi Sandstone rock.

Saurabh Kumar, H. K. Pandey

Evolutionary Topology Optimization of Structural Concrete Under Various Load Cases

Topology optimization has wide applications in the field of engineering as it derives the optimum material layout in a given design space with defined loads and boundary conditions. This article presents the topology optimization of structural concrete with different load cases using a bidirectional evolutionary structural optimization method (BESO). BESO method has several advantages over other optimization methods as it removes inefficient elements and adds efficient elements in each iteration. The methodology adopts the compliance minimization with volume constraint by utilizing the capabilities of ABAQUS finite element software. Strut and Tie model (STM) has been identified as an effective method in modeling discontinuity regions in reinforced concrete structures as it can find out the real load transfer mechanism in structures. With the aid of topology optimization, all the uncertainties related to STM can be avoided.

V. R. Resmy, C. Rajasekaran

Numerical Analyses of Geogrid Reinforced Embankment Over Soft Clay

Construction of embankments on weak foundation soils is a challenging task for civil engineers due to excessive settlement, bearing capacity failure and slope stability issues. To solve this problem, a variety of ground improvement techniques, including vertical drains, grouting, complete soil replacement, geosynthetic reinforcement and piling, are adopted. Geosynthetics provides an alternative and economical solution and has been increasingly applied as reinforcement in embankments on soft soil. In the present study, 3D numerical analyses using the finite element program ABAQUS was carried out to study the time-dependent behaviour of geogrid reinforced embankment. Parametric studies were carried out by varying the height of the embankment.

C. Keerthana, M. P. Vibhoosha, Anjana Bhasi

Tensile Properties of FRP and Ferrocement—A Comparative Study

An experimental investigation was carried out to obtain the equivalent tensile properties of different composite laminates, namely glass fibre-reinforced polymer (GFRP), carbon fibre-reinforced polymer (CFRP) and ferrocement. This work is part of a study on the application of these composites for the purpose of rehabilitation/retrofitting of RCC structural elements under distress. Tension tests were conducted on flat coupons of FRPs based on ASTM D7565/D7565M-10 and ASTM D3039/D3039M-00. Similar tension tests were conducted for mesh reinforcement used in ferrocement. The CFRP consists of unidirectional carbon fibre-woven mats (230 g/m2) in an epoxy matrix (resin used was EPS), GFRP consists of bidirectionally woven glass fibre mat (225 g/m2) in the same epoxy matrix and mesh reinforcement for ferrocement consists of woven square GI wire mesh of gauge 12/29 (0.35 mm diameter wires at a spacing of 2.12 mm). Coupons of 25 mm width were made from the three different composites and tested until failure under tension in a digital universal testing machine. To find the equivalent number of layers of FRPs and mesh reinforcement in ferrocement, a total number of (i) 10 CFRP, (ii) 25 GFRP and (iii) 20 ferrocement tension specimens with a different number of layers were prepared. All coupons were tested to failure and the results are presented. It was found that GFRP with three layers and ferrocement with five layers of mesh reinforcement are equivalent to one layer of CFRP, based on the tensile strength. Similarly, CFRP with 2 layers is equivalent to GFRP with 7 layers and mesh reinforcement of 11 layers in ferrocement, for the materials considered in the study.

P. Bindurani, N. Ganesan, P. V. Indira

Analysis of PVD with Vacuum and Surcharge

Improvement of soft clay for making the ground viable for construction has always been a dynamic area of research. One such ground improvement technique being widely used is the inclusion of Prefabricated Vertical Drains (PVD) in the soil to accelerate the consolidation. The effectiveness of using PVD can be further improved by combining surcharging with vacuum preloading. The paper deals with the 2D numerical modeling of soft soil stabilized with vertical drains subjected to combined vacuum-surcharge preloading using the finite element program ABAQUS. The predictions of settlement and pore-water pressure were compared with the experimental data reported in the literature.

R. Sujana, Anjana Bhasi

Drivers Perspective on Wearing Seat Belt and Use of Mobile Phone While Driving in Metropolitan City

Motorbikes and cars share a highest proportion (33.9 and 24.5%) of total crashes. Most of these crashes result in crash tragedy which increases the severity and is a result of not wearing seat belt or use of mobile. The study aims in analyzing the perspective of drivers toward wearing seat belt and use of mobile phone. Online and field survey was conducted along with observational survey. A logistic regression analysis is carried to find the risky factors influencing not to wear seat belt and use of mobile. It is observed that nearly 50% of drivers are not wearing seat belt, and 94.1% of passengers in rear end were also not wearing seat belts. Wearing seat belt by yellow plate drivers is 10% less that of white plate drivers. The use of mobile phone was noticed during morning hours of the day in the age group of 26–35 years. The highest risk of not wearing seat belt and use of mobile phone was observed on minor roads among the age group of 36–50 years and on weekends. The factors influencing are type of car, road type, time of day, and day of the week which are found to be significant for wearing seat belt and use of mobile phone. The results from this study will be useful for reducing the crash severity rates by implementing appropriate awareness and enforcement programs in and around the metropolitan cities.

Ballem Praveen, Adepu Ramesh, Molugaram Kumar

Calibration of Fundamental Flow Model for Pedestrian Sidewalks in Urban Areas

Walking is one of the major modes of transportation, but pedestrian facilities are often neglected or given with the least preference when compared with the motor vehicles by the town planners and engineers for the safety and comfort of pedestrians, it is important to design and operate the pedestrian facilities like sidewalks, walkways, and crosswalks. Hence, a scientific study is essential to understand the parameters affecting pedestrian flow and to mitigate the same to provide a safe, comfortable, and convenient environment for pedestrians along sidewalks. This research studies the macroscopic stream model of pedestrian movement along sidewalks and develops a new model consisting of these macroscopic parameters (speed, flow, and density) for Indian scenario. Some of the macroscopic models discussed in this study are the Greenshield’s macroscopic model, Greenberg Logarithmic model, and Underwood Exponential model. Based on these models, the maximum free-flow speeds and jam densities are calculated and the fundamental graphs are plotted based on their relationships between parameters. R software was used to analyze and determine the best fit statistical distribution for the observed pedestrian data for the selected sidewalk locations. Using the best fit distribution, based on pedestrian speed and density, a model is being generated for predicting the pedestrian flow.

Nirnay Chintawar, Teja Tallam, K. M. Lakshmana Rao

Determination of Level-of-Service for Public Transport: A Case Study for Hyderabad Metro

Public transportation is a predominant bestowing factor for attaining urban sustainability. Effective transportation networks that incorporate public transit helps in lowering the city's per capita carbon footprint, and make cities more livable by easing commute and transportation needs and increasing accessibility. Performance of any public transport depends on its qualitative and quantitative measures. The utilization of any public transport can be increased by improving the service quality and operational efficiency. An attempt is made to find out the service quality measures of Hyderabad Metro by conducting a commuter survey of 1500 passengers and evaluating the Level-of-Service (LOS) using a combination of Analytical Hierarchy Process (AHP) and numerical rating analysis. The transit performance can further be improved by ameliorating the weaknesses discovered. The LOS of Hyderabad metro was depicted to be 0.752 on a scale of 1, and the attributes that should be improved to increase the LOS are ticket fare and parking spaces.

Teja Tallam, Harshini Yallabandi, C. Naveen Kumar

GFRP Reinforced RC Deep Beam with Multiple Web Openings

Deep beams are members with clear spans to depth ratio equal or less than four times the overall depth. Reinforced Concrete (RC) deep beams are used as load-distributing structural elements such as transfer girders, pile caps, foundation walls and offshore structures. Due to some structural and aesthetical aspects, provision of openings with square, rectangular and circular shapes are provided in the beams. These openings are made mainly for providing conduits and ducts. These provisions are mainly used for the reduction of space in high rise buildings. In offshore construction, the corrosion of reinforcement is the major threat to the structural integrity of the structure. To overcome this corrosion problem, Fibre Reinforced Polymer (FRP) reinforcements are employed under such extreme situations. The non-corrosive nature of FRP reinforcements enhances the serviceability of the structures. The present study was aimed to determine the ultimate load-carrying capacity, ultimate shear-carrying capacity and crack propagation of deep beams reinforced internally with Glass Fibre Reinforced Polymer (GFRP) reinforcements with multiple circular web openings. The deep beams of size 1100 mm × 150 mm × 450 mm were cast. Two different reinforcement ratios of 0.50 and 0.84% provided at the bottom with top reinforcement of 0.33%. A total of six beams with multiple circular web openings were cast, out of which four beams with GFRP and remaining two beams cast with conventional Steel reinforcement. The ultimate load-carrying capacity, ultimate shear-carrying capacity, number of cracks, mode of crack formation, and direction of crack propagations were observed. The theoretical and analytical predictions were carried out for load- and shear-carrying capacities. These results were compared with experimental results.

R. Murugan, G. Prasanna

Influence of Superplasticizers on Blended Cement and Their Effect on Flow Characteristics by Incorporating PGBS as Partial Replacement for Fine Aggregates

Currently the upsurge practice of the mineral admixtures as an alternative for cement to cut down the carbonic gas emission, to reduce the cement cost, and to progress some technical recitals is truly the indispensable novelty advanced in construction industry. Mortars with different w/c require the use of appropriate and compatible chemical admixtures to achieve desirable consistency. The principal tactic delivered to contest in contradiction to this exertion is to choose the furthermost effective twosome cement–superplasticizer, facilitating to attain a determined water reduction, an enhanced flow, and an adequate rheology. Processed Granulated Blast Furnace Slag (PGBS) incorporated as partial replacement for Fine Aggregates (FA) along with different types of Superplasticizers (SP) for different dosages, which were chemically based on Lignosulfonate (LS), Sulphonated Naphtha Formaldehyde (SNF), and Polycarboxylate Ether (PCE), was used to check the behavior of flow characteristics in this work. The fusion of Portland pozzolana cement (PPC) along with partial replacement of fine aggregates has resulted to understand the better flow interaction between the cementitious materials and under different water–cement ratio (w/c).

D. Arpitha, V. J. Sudarshan, Y. T. Thilak Kumar, C. Rajasekaran

Investigations on Flow Characteristics of Mortars Using Partial Replacement of Fine Aggregates with Processed Granulated Blast Furnace Slag

Sand has always been an integral part of construction in our civilization. It has been the most easily available and acceptable source for the same. However, the depletion of river sand availability has led us to start looking at the alternatives including some industrial by-products. Processed Granulated Blast Furnace Slag (PGBS) is an alternative slag sand for fine aggregate which is being extensively utilized. Low density and strength issues concerned with Granulated Blast Furnace Slag (GBS) have led to the innovation of PGBS. PGBS is considered as an economically viable and environmentally acceptable alternative material for replacing river sand having tremendous economic impact, conservation of natural resources, and gainful recycling of process by-products. In this study, mini slump cone test is conducted for mortars using 10, 20, 30, and 40% partial replacement of Fine Aggregates (FA) (River sand) with PGBS to study the flow behavior and to identify the suitable combinations of water binder ratio (W/B) (0.4, 0.45, and 0.5) and superplasticizer dosage (0.2, 0.4, 0.6, 0.8, 1.0, 1.2, 1.4, 1.6, 1.8, and 2.0).

V. J. Sudarshan, D. Arpitha, Y. T. Thilak Kumar, C. Rajasekaran, Nagesh Puttaswamy

Development of Satellite Data-Based Multiple Regression Equations for the Estimation of Total Coliform and Petroleum Hydrocarbons Along South West Coast of India

Coastal waters are showing deteriorating trend in its quality. This leads to the damage of marine ecosystems and interferes in its normal use. In order to tackle this issue, it is important to know about the extent of pollution. Conventional method of water quality estimation includes analysis of water samples from various locations. This is a tiresome and costly process limiting its application to small scales and accessible sampling sites. In this paper, an attempt has been made to quickly estimate the concentration of Petroleum Hydrocarbons (PHC) and counts of Total Coliform (TC) which are important water quality parameters, along the south west coast of India. This study formulated satellite data-based multiple regression equations for determining the count of total coliform bacteria and concentration of petroleum hydrocarbons. The sea surface temperature and remote sensing reflectance values of different bands of MODIS sensor along with field values were used in the process. The developed algorithm is validated for future use. Maps are created using these equations, showing the distribution of these parameters along the coast using Moderate Resolution Imaging Spectroradiometer (MODIS) and Visible Infrared Imaging Radiometer Suite (VIIRS) data. Hence, the feasibility of VIIRS for determination of these parameters with the same algorithm is examined. Thus, based on the results, areas of high PHC and TC could be identified and necessary control measures could be adopted.

Dinu Maria Jose, Venkata Ravibabu Mandla, Srinivasa Rao Neerukattu, Sri Venkata Subbarao Saladi

Analysis of Thin Plates Using Applied Element Method

Applied Element Method (AEM) is a numerical method for structural analysis developed in the year 1997. It is very efficient in terms of accuracy, memory requirements and processing time. It is able to capture the structural behaviour up to collapse. AEM is extended to the analysis of thin plates in this paper. Few modifications are made in the conventional applied element to bring in the behaviour of thin plates. Convergence study is done and is compared with that of Finite Element Method (FEM). The computational time of AEM and FEM are also compared. The displacement and force resultants of few classical problems are determined. This is done for plates with different length to width ratios. The deflection, bending moments and shear forces are close to that of Classical Plate Theory. The complementary shear stress distribution is parabolic across the depth and the normal stress distribution is linear. Hence, it is found that AEM is effective for the analysis of thin plates.

D. Lincy Christy, T. M. Madhavan Pillai, Praveen Nagarajan

Study of Tilt on Adjacent Strip Footings

The primary function of the foundation of a structure is to safely transfer the loads from the superstructure to the soil beneath without occurrence of shear failure and excessive settlements. Due to rapid urbanisation, very often structures and their foundations are built close to each other. Foundation of the newly built and the already existing structures interferes with each other to some extent depending on their relative positions. Due to large stresses at points between the footings (due to overlapping of stresses), there is a non-uniform pressure distribution beneath the footings and beyond in the gap between the footings. There is an increase in stresses from the outer edge of the footing to the inner edge. This causes tilt in the footings. This numerical study looks into the tilt of two adjacent strip footings on the surface of cohesive and cohesionless soils. Numerical analysis using a finite element-based software is being used. The parameters varied in this study are the clear distance between the two adjacent rigid strip footings and width of the footings. One of the footings representing an already existing foundation is loaded with half of the estimated failure load of isolated footing and adjacent footing loaded up to failure. The effect of interference is observed to be particularly significant in terms of the tilt.

S. Anaswara, R. Shivashankar

Structural Stability of Cold-Formed Steel Wall Studs Under Compression by DSM Approach

The significance of the application of Cold-Formed Steel (CFS) in residential and industrial structures depends upon the stability and the sustainable load-bearing criteria. The main element in the CFS wall panel assembly is its studs, which bear all the compressive load in the wall system. The parametric study on the CFS wall stud is important to assess its variation in axial load-carrying capacity when stiffeners are used in its cross-section. In this study, the variation of the strength of wall stud made up of C-type section has been done by performing the finite strip analysis to assess their elastic buckling loads in Confined and Unconfined Finite Strip Method (CUFSM) tool of version 4.05. The parametric variation considered here is the change in size configuration, length of the section, thickness of cross-section, using web and flange stiffeners in the cross-section, and dimension of lip in the cross-section. The results obtained for each specimen by the Direct Strength Method (DSM) of the American Iron and Steel Institute (AISI S-100) (Appendix-2) procedure. The semi-analytical DSM approach is the robust procedure to evaluate the CFS wall studs under with and without sheathed condition for the axial strength. The important aspect of this study is to explore the variety of results obtained when both standard and optimized sections are analyzed for nominal axial strength. This study could be further utilized for the study and design purpose of CFS wall panels.

Abhinav Dewangan, Govardhan Bhatt, Chanchal Sonkar

A Model for Estimation of Critical Gap and Its Distribution Behaviour at Un Signalised Intersections

Traffic congestion on the urban road network is a result of the increase in vehicular traffic as it is characterized by slow speed, longer trip lengths, and longer delays. Unsignalized intersections are provided for low volume traffic flow and its performance is also used to evaluate urban road networks. Delay is considered as the important parameter and evaluation of unsignalized intersections is achieved through gap acceptance behavior. Gap acceptance behavior is an important parameter for the determination of capacity and at unsignalized intersection. This article explicitly presents an overview of the estimation of critical gaps at unsignalized intersections by conventional methods like Raff’s method and maximum likelihood method. The parameters are compared with Indo-HCM for better identification of traffic characteristics. Data are collected through video graphic techniques at two locations in Hyderabad. Traffic parameters like speed, volume, approaching vehicle type, accepted and rejected gaps were extracted. The study has also examined the variables associated with occupancy factor, vehicle type, and socio-demographic features. It is observed that conventional Raff’s method gives accurate results compared with other methods for different types of vehicles. Indo-HCM is also one of the most simplified techniques and gives precise values, and the critical gap values vary at a difference of 0.15 s compared to Raff’s method.

M. Satya Deepthi, A. Ramesh

Critical Review on Stress-Sensitivity and Other Behavioral Aspects of Arch Dams

Dams have an important role in the economic and social development of a nation. As per ICOLD statistics, there are not less than 59,071 registered large dams in the world of which 2332 are arch dams. Some of the existing dams have deficiencies w.r.t. design and some of them may not meet the present design standards. Further, apprehensions on the health of some of the dams have been raised on account of aging. Safety of dams is of paramount importance and warrants utmost priority as the water stored is a potential source of threat to the life and property of the stakeholders downstream of the structure. Safety inspections and safety evaluations of existing dams would cast light on whether the dam has any structural, hydrological, and operational deficiencies and if there is any deterioration. Periodical structural evaluation using advanced technological interventions are indeed essential. The behavior of arch dams differs unpredictably vis-à-vis that of other types of dams due to its shape, the mechanism of transfer of loads, and the response of the dam body against such loads. Identification of the nature and magnitude of loads acting on the arch and consideration of all possible combinations of loads is an important part of engineering analysis. Safety evaluation of an arch dam shall highlight the issues of strength, stability, and vibrations, as well as special problems of arches and arched structures when subjected to the anticipated loads. Modern-day engineering has solutions for problems related to the strength and stability of arches, and vibrations encountered in its life period. Galleries and other openings are integral parts of arch dams too. Stress contours and intensities of stresses at various salient locations, cantilever motions/periodic movements of an arch dam vis-à-vis fluctuating impoundment levels, the effect of stress reversals due to temperature variations, dynamic behavior due to seismic loads, etc., are to be computed and analyzed to understand the behavior of the dam. Computational models using the finite element method (FEM) are capable of modeling and simulating the dam structure as well as the dam–fluid–foundation interaction, In this paper, a brief review of literature pertaining to structural analyses of arch dams and case studies on its behavioral aspects under various loading scenarios is presented. Some of the issues that require further investigation will be highlighted.

K. Jiji Panicker, Praveen Nagarajan, Santosh G. Thampi

Assessment of Safety of a Retrofitted Damaged Reinforced Concrete Column Based on the Bond Stress and the Stress Transfer at the Interface of the Reinforced Concrete Jacket and the Old Concrete

Reinforced concrete columns in buildings undergo damage due to earthquakes, under-designed or erroneous designs, exposure to high temperatures, or due to overloading. Damaged reinforced concrete columns affect the safety and stability of the overall building. Hence, damaged reinforced columns are retrofitted to restore them, from strength and stability aspects, to improve their load-carrying capacity. In this study, retrofitting of an existing damaged reinforced concrete column of a commercial building has been carried out. The bond stress developed at the interface of the reinforced concrete jacket and the old concrete corresponding to the damaged reinforced concrete column is assessed by carrying out a three-dimensional finite element analysis. Based on the magnitude of the developed bond stress, the number of shear connectors to be provided to anchor the old and new concrete in the reinforced concrete jacket is decided. The shear and axial stresses developed in the shear connectors are also checked with the corresponding permissible material strength values. The safety of the retrofitted reinforced concrete column is assessed based on the bond stress values; the shear and axial stress developed in the shear connectors; and the number of shear connectors provided at the interface of the damaged reinforced concrete column and the reinforced concrete jacket.

Y. K. Guruprasad, K. S. Jayasimha

Parametric Response Estimation Study on Cantilevered and Strutted Diaphragm Walls

Diaphragm walls are ideal solution for the productive utilisation of underground space to meet the modern-day demands of infrastructural development. The selection of appropriate wall and support configurations has a substantial impact on the economy, time and performance. Unsatisfactory implementation of such retaining systems during or after construction may cause heavy causalities. The practical significance of excavation induced deformations is large due to its potential damage to adjacent structures. Hence, reliable estimates of excavation related responses are vital for construction and implementation of diaphragm wall projects. Numerical studies performed to understand the effects of factors such as ground characteristics, excavation geometry and support criteria in the response of diaphragm walls are presented here. Detailed parametric analysis is conducted to comprehend the combined effects of these factors on both cantilevered and strutted diaphragm walls. Walls embedded in cohesive and non-cohesive backfills with varying groundwater locations are considered. Properties of struts and their influence on excavation geometries for various ground characteristics are assessed. Studies are performed to obtain the most effective combinations of excavation and embedded depths for cantilevered diaphragm walls. Numerical analysis was conducted using finite element software Plaxis 2D and values of lateral deflections, normal forces, bending moments, shear forces and axial strut forces are computed. Comparative charts are drawn to demonstrate the variations of wall responses with different combinations of influencing factors. Ideal wall and support configurations for any given ground conditions and excavation geometry can be perceived from the charts enabling fast and cost-effective implementation of projects.

Anu James, Babu Kurian

Numerical Studies on Impact Response of Reinforced Concrete Beams Using FE Software

Recently, the demand for structural safety subjected to blast and impact loading has been increased. For this reason, various studies for predicting the behaviour of structures under blast and impact loading have been actively performed. Finite Element Analysis (FEA) represents a numerical method, which provides a solution to problems that would otherwise be difficult to obtain without incurring significant expenses. In the present study, the impact energy absorbed by the reinforced concrete beam under point impact load up to the formation of initial cracks and their crack pattern, under falling-weight impact was studied numerically using FE software ANSYS. Simply supported rectangular reinforced concrete beams of 100 × 100 mm in cross-section and 1200 mm overall length was used to compare the impact response of RCC beams of different reinforcement percentages (0, 0.56, 1, 1.57 and 2.26%) using FE software to assess the effect of reinforcement on the impact behaviour of reinforced concrete beams. The impact energy absorbed by the beams were increased with an increase in the percentage of reinforcement up to a certain extent. Afterwards, it decreased due to an increase in the brittleness of the beam after crossing the over reinforced limits.

Anand Raj, B. Kiran Kumar Reddy, Praveen Nagarajan, A. P. Shashikala

Numerical Studies on Impact Response of Prestressed Beams Using FE Software

Impact is a high-intensity shock load applied for a short interval of time. Such a force is more damaging than a lower magnitude force applied over a proportionally longer period of time. Prestressed concrete (PSC) beams encounter these loads from a variety of sources during their service life as structural members. Here, an endeavour to carry out numerical studies to study the effect of prestressing force on the impact resistance of a PSC beam is undertaken using finite element software ANSYS. In this paper, a simple supported rectangular prestressed concrete beam of 100 mm × 100 mm in cross-section and 1200 mm length is used to compare the impact strength of prestressed beams due to prestressing forces of 4, 6, 8, 10 and 12 kN. The results of the study indicate that the capacity of the beam to absorb energy increases with an increase in prestressing force.

Anand Raj, Raunak Kumar, Praveen Nagarajan, A. P. Shashikala

Fracture Behaviour of Steel Fibre Reinforced Rubcrete

Discussions on the failures in quasi-brittle materials like concrete provide a better understanding of its response to loadings when it is presented with the backdrop of fracture mechanics. Rubcrete is a term used to denote a concrete in which mineral aggregates are replaced by crumb rubber. An idea about the energy utilised to open the unit area of a crack surface can be obtained by using Fracture Energy (Gf). Results of experimental investigations on M40 grade concrete with steel fibres and crumb rubber to determine the Gf as per RILEM TC50 FMC is presented in this paper. The rubcrete variants considered in this paper include M40 grade concrete in which fine aggregates are replaced by 5, 10, 15 and 20% with crumb rubber. The steel fibre reinforced concrete variants have steel fibre proportions of 0.25, 0.5, 0.75 and 1% of the total volume of the mix. Steel fibre reinforced rubcrete mixes have a rubber content of 15%. It can be concluded that, with the addition of steel fibres of about 1% by the total volume of the mix, the Gf increases by 51% and 84% for the ordinary concrete and the rubcrete specimen, respectively.

Anand Raj, P. J. Usman Arshad, Praveen Nagarajan, A. P. Shashikala

Performance of Diagrid Structures with the Addition of Shear Links

Diagrid structures are an innovation in high-rise buildings for the efficient resistance of lateral loads. They can be considered as an extension of the truss system, as they consist of triangulated modules in the exterior in place of vertical columns in conventional framed tubular structures. The triangulated system contributes to the structural efficiency, i.e. the lateral and gravity loads are transferred through the axial action of the members. The disadvantages of diagrid structures are their limited energy dissipation capacity and ductility. In order to overcome this difficulty, the incorporation of shear links to the diagrid system is suggested. This paper aims in assessing the performance of shear links in diagrid buildings. In this paper, shear links of different lengths are introduced in diagrid frames and comparison of the performance is evaluated.

Minu Ann Peter, A. S. Sajith, Praveen Nagarajan

Design of Box Girder Bridges Using Simplified Frame Analysis

As box girder bridges are inevitable kind in the field of bridge engineering, studies on them is always a fascinating job for researchers. The inherent nature of its cross-section can resist many structural actions. Even though, the geometry of these kinds of bridges is simple their design procedures are not. Mostly Three-Dimensional Finite Element Analysis (3D-FEA) is done to design these structures. As 3D-FEA is time consuming, various simplified methods are used by design engineers for the preliminary study and analysis. Simplified Frame Analysis (SFA) is one among such simple methods used by bridge engineers to conduct trial design on box girder bridges. SFA is an easy method to find the transverse bending moments in box girder bridges. This paper focuses on how to use the results of Simplified Frame Analysis (SFA) for the transverse design of box girder bridges.

J. Chithra, Praveen Nagarajan, A. S. Sajith

Use of FEM for Design of Reinforced Concrete Beams as Per IRC 112-2011

To design reinforced concrete beams, engineers all over India refer to IS 456-2000. Nowadays finite element software is used for any design rather than hand calculations. In the appendix of the latest revised code for bridges IRC 112-2011, design procedures using three-layer sandwich model based on finite element analysis has been included for the design of reinforced concrete structures. In the sandwich model, a shell element is divided into three layers. The top and bottom layer are supposed to take out of plane moments and the core carries out of plane shear. In this paper, sandwich model has been used for the design of reinforced concrete beams. Here solid and hollow rectangular beams are considered for the design. The results are then compared with IS 456-2000.

J. Chithra, Praveen Nagarajan, A. S. Sajith, R. A. Roshan

Estimation of Ultimate Strength of Concrete Box-Girder Bridges Using Space Truss Analogy

The box section has high torsional stiffness and bending stiffness which makes it a very efficient structural system to resist different forces acting on it. Owing to its complex geometry, the analysis and behavior at the ultimate stage of a box-girder bridge are not yet completely understood. Among the existing theories, Space truss analogy is the basic theory to understand the behavior of box sections at its ultimate stage. For reinforced concrete box-girder bridges subjected to a combined action of bending and torsion, space truss analogy visualizes the structure as a space truss formed by inclined diagonal concrete elements as struts and reinforcing cage as ties. In the present study, box-girder bridges are modeled and their ultimate strength is predicted using the theoretical formulations of space truss analogy and strut and tie model. In analysis, the various load patterns are considered to incorporate the actual bending and twisting effects which are generated due to eccentric load. The numerical computations for the space truss are performed using STAAD, and the results are compared with those available from literature.

Bajare Mayur Mangesh, J. Chithra, Nagarajan Praveen, A. S. Sajith

Performance Evaluation of Geopolymer Concrete Beam-Column Joints Using Finite Element Methods

The beam-column joints are the most critical zones in a reinforced concrete building. They are subjected to forces in all directions during earthquakes, and their behaviour has a significant influence on the structure. Thus, highly ductile materials are required for the design of beam-column joints. Geopolymer concrete is environmentally friendly and contributes to sustainable development. As it attains higher compressive and tensile strengths and increases the durability of structures, it can be an effective substitute to OPC. The use of Finite Element Analysis (FEA) to analyse various structural components is gaining widespread importance nowadays. The aim of this paper is to predict the behaviour of GGBS-dolomite geopolymer concrete exterior beam-column joints using ANSYS. Limited experimental studies have been done and further behaviour is studied using Numerical Methods. For this purpose, constitutive relationships are developed from experimental investigations. The displacements, stresses, strains and forces at any point can be determined under different loading conditions. The deflection characteristics, first crack load and ultimate load of beam-column joints are determined. Non-linear finite element analysis is carried out in several load steps taking care of the force and displacement convergence criteria to study the specimen’s behaviour from first crack load to ultimate load.

Aravinda Rajhgopal, P. Saranya, Praveen Nagarajan, A. P. Shashikala

Numerical Studies on GGBS–Dolomite Geopolymer Concrete Short Columns

In recent years, Geopolymer Concrete (GPC) is gaining popularity as a greener construction material compared to conventional concrete which is made up of Ordinary Portland Cement (OPC). Many studies have been conducted on fly ash and GGBS-based geopolymer concrete. The use of GGBS and dolomite to form GPC will increase the workability of concrete. In addition to this, the overall cost is also expected to come down as dolomite is a cheaper industrial waste. Since the strength development mechanism of GPC is different from that of OPC binder, it is necessary to obtain a suitable constitutive model to predict the load–deflection behaviour and strength of GPC structural members. The aim of this paper is to predict the behaviour of short columns subjected to axial load using ANSYS, a commercially available finite element software. The analysis determines the displacement, stresses, strains and forces at any point under different boundary conditions. The deflection, ultimate load and crack pattern have been determined from the model.

Akash Kumar Behera, P. Saranya, A. P. Shashikala, Praveen Nagarajan

Effect of Double Plastic Hinges on Seismic Performance of Strengthened Column

The RCC bridge columns are generally severely damaged during disastrous earthquakes. Traditionally, strengthening methods by bonding with steel plate, FRP or other strengthening materials are employed in RCC columns. The deformation capacity is improved for strengthened column, and they can withstand large earthquake due to the energy dissipation effect of the non-elastic phase. The plastic hinge formation is a major factor in the deformation of the column and plays an important role in the seismic performance of the column. Strengthening partial height of column with steel plate and by optimizing the plate thickness, two plastic hinges could be formed simultaneously at two positions, one at the column bottom and other at the upper edge of the strengthening steel plate. A cantilever bridge column of rectangular hollow section is modelled in ABAQUS, and a comparative study on the seismic performance of the unstrengthened and strengthened columns with single and double plastic hinge is done. In the column, the double plastic hinge formation improved the ultimate deformation, stiffness and its strength capacity.

C. U. Aswin, Alice Mathai

Plastic Hinge Relocation in RCC Double-Slotted Beam Connection

Plastic hinge relocation is the technique to relocate the plastic hinge away from the beam-column junction, i.e. to the beam. Over last few years, several plastic hinge relocation techniques were introduced to avoid penetration of strain into beam-column junction and to ensure strong column–weakbeam behaviour. The main drawback of these techniques is difficulty in prediction of centre of rotation of beam element. In this paper, an innovative type of beam-column connection known as Double-Slotted Beam (DSB) is developed, as a plastic hinge relocation technique with high level of accuracy in prediction of centre of rotation. Here, the beam consists of two vertical slots at top and bottom fibres of beam member. The slots are introduced to control the location of centre of rotation. The location of vertical slots is shifted from face of column towards the beam in each specimen, in order to relocate plastic hinge away from beam-column junction. Finite element analysis of beam-column connection with and without vertical joints was done using ABAQUS, in order to study the behaviour of structure under seismic loading. Displacement-controlled cyclic analysis of DSB connection was conducted. The double-slotted beam connection achieved plastic hinge relocation, minimum damage in concrete and reduction in deterioration of bond in joint.

Anandhu P. Haridas, Alice Mathai

Evaluation of Reliability Index for the Steel Beam Designed Using IS 800:2007

This study presents an evaluation of the reliability index of the steel beams designed according to limit state of collapse in flexure as per IS 800:2007. The safety evaluation is based on structural reliability analysis of beams using Hasofer and Lind’s method, which are laterally supported. The parameters, yield stress, dead and live loads are considered as random in the reliability evaluation. It is assumed that failure function is a linear combination of basic variables. The effects of geometrical imperfections and stresses in beam are taken into account.

Chinnu Sabu, Praveen Nagarajan, P. Robin Davis

Experimental Investigation on Bond Strength Properties of Geopolymer Concrete

Geopolymers are new alternative binders for the development of concrete. Geopolymer concrete can overcome the environmental impact of cement concrete. Highlight of the work is development of geopolymer concrete from industrial by-products such as Ground Granulated Blast Furnace Slag (GGBS) and dolomite. Performance of structural elements mostly depends on the bond between concrete and reinforcement. Enhanced bond stress was observed in geopolymer concrete than that of cement concrete. Different equations were evaluated for the prediction of bond stress. Effects of addition of different percentage of dolomite on bond strength are also investigated. Addition of GGBS and dolomite can reduce the production cost of concrete and can also reduce its disposal problem.

P. Saranya, Praveen Nagarajan, A. P. Shashikala

Numerical Procedures for Simulation of Wave Propagation in Plates

Structural health monitoring (SHM) using wave propagation technique is an emerging method that can be used to detect, locate, and quantify the structural damages before catastrophic failures. Advancement of several finite-element simulation programs has helped scientists and engineers in validating the numerical solutions with the experimental results. Most of the researchers use explicit procedures for wave propagation problems. However, for electromechanical problems where piezoelectric materials are used for exciting waves, the explicit procedure is not available in most cases. Hence, implicit procedures are used to account for the piezoelectric effect. It becomes necessary to choose which procedure is apt for obtaining sufficient accuracy and to run the problem within reasonable computational time. This paper presents a comparative study of different finite-element procedures for modeling wave propagation in plates. Three different analysis procedures are studied, namely implicit analysis, explicit analysis, and implicit–explicit co-simulation analysis. The results show that the co-simulation model is more reliable and efficient compared to other models.

Mohammed Aslam, Praveen Nagarajan, Mini Remanan

Study on Compatibility Issues and Flow Behavior of Copper Slag-Based Mortars

With the growing constructions industries, sand availability has become a headache for the builders and engineers. In this paper an attempt has been made to understand the flow characteristics of partially replaced copper slag (10, 20, 30, and 40%) in mortars with varied water binder ratio (0.35, 0.4, and 0.45) for different percentages of superplasticizers dosage (0.2, 0.4, 0.6, 0.8, 1.0, 1.2, 1.4, 1.6, 1.8, and 2.0). Thus, the test results drawn help to identify the optimum dosage of superplasticizer required for different percentage replacement of fine aggregates and water binder ratio and understand the flow behavior characteristics of mortars.

Y. T. Thilak Kumar, D. Arpitha, V. J. Sudarshan, C. Rajasekaran, Nagesh Puttaswamy

Properties of Coconut Shell Aggregate Concrete: A Review

The demand for concrete has increased since it became an unavoidable construction material worldwide. Coarse aggregate is one of the main ingredients of concrete. Depletion of aggregate deposits occurs due to continuous extraction of aggregates, which leads to environmental degradation and thus ecological imbalance. Therefore, trends in concrete technology are currently directed toward searching for alternative sustainable materials for aggregate in order to minimize over reliance on natural resources. Many substitute materials such as aggregates from industrial wastes and byproducts are used for production of concrete. Coconut shell is a waste material from agricultural industries and available in plenty throughout the tropical regions worldwide. Coconut shells are used for many useful purposes, but most of the coconut shell wastes are yet to be utilized commercially. A promising solution to the challenges in coconut waste management involves coconut shell as aggregate in concrete. Many researches were conducted on coconut shell aggregate concrete in the last decade. This paper presents an overview of physical, mechanical and chemical properties of coconut shells, followed by a discussion on the physical, mechanical, bond and durability properties of coconut shell aggregate concrete. Structural behaviors such as shear, flexure and torsion of coconut shell aggregate concrete are also discussed. Some applications of the coconut shell aggregate concrete are also highlighted. The current understanding of coconut shell aggregate concrete provides basis for further research in this field.

A. Sujatha, S. Deepa Balakrishnan

Effect of Rigidity on Seismic Analysis of Structures

In response spectrum method, the modal seismic response is a combination of the damped periodic part and a rigid part. In high-frequency modes, the damped periodic part of the response is negligible and the response becomes rigid. The proposed methods and the current practices that have been used to account the effect of rigid part of the response into the seismic analysis of structures and their modal response combination methods are reviewed. Case studies on (i) a squat shear wall with an aspect ratio less than unity to show the behavior of a structure in high-frequency region of a spectrum and (ii) a building with a stiff base supporting a tower to show the effect of “missing mass” on the seismic analysis of structures with rigid modes are presented. The paper concludes with a set of methods for considering the effect of rigidity in earthquake analysis of irregular structures based on the latest developments in the field.

M. Dhileep, P. D. Arumairaj, G. Hemalatha, M. S. Sandeep

Effect of pH on Compressibility Behaviour of Cement-Treated Soil

To enrich the performance of structures, the stability of underlying soils must be checked. The stability of soil may change due to discharge of pollutants into water bodies without adequate treatment which causes momentous changes in the behaviour of water and further leads to changes in the pH of water. In the present study the black cotton soil has been treated with ordinary Portland cement of 53-grade and Portland slag cement with different percentages (3, 6 and 9%), and laboratory tests such as Atterberg limits, compaction, UCS, CBR and consolidation have been performed. This paper attempts to assess the effect of pH (pH = 5, 7 and 9) levels on curing time (7, 14 and 28 days) behaviour of cement-treated soil. Test results have shown that there is an increase in OMC which leads to decrease in MDD. The UCS and CBR strengths of soil got increased due to the addition of cement; besides that, there is a reduction in the compressibility with the addition of cement content which were cured for ages (7, 14 and 28 days).

Suresh Kommu, SS Asadi

Simplified Grid Strut and Tie Model Approach for Shear Walls

Conventional strut and tie model for certain structural elements are not well established. Alternative methods that evolved later are inappropriate for general practice. A new simplified grid strut and tie method is introduced in this paper. For checking the effectiveness and reliability of the proposed method, a model of slender shear wall with staggered openings was developed and compared with the experimental and numerical analysis available in the literature. Results were promising as it predicted the failure modes satisfactorily.

Kannan C Bhanu, N. Ganesan, P. V. Indira

Analysis of RC Buildings by Metamodel Approaches

Response of RC structures is very complex and dynamic in nature because of the vulnerabilities that exist in geometry, material properties and loading. To represent the random dynamic responses accurately, stochastic analysis is chosen here. The stochastic analysis can be done by two types of methods, like statistical and the non-statistical approaches. In non-statistical approach a relationship is developed between the input and random output or responses. Computationally efficient, simplified methods are required as an alternative to Monte–Carlo simulation which is considered as an accurate method for stochastic analysis. The present study is an evaluation of the different non-statistical metamodel-based approaches such as high-dimensional model representation and using design of experiments approaches like central composite design, Box–Behnken design and full factorial design for the representation of the response surface. The effectiveness of high-dimensional model representation over conventional response surface metamodel approaches is discussed in the present study with regard to two contexts, namely free vibration response and nonlinear time history responses of RC frames. The seismic fragilities obtained using high-dimensional model representation are compared with established metamodel approaches for effectiveness and computational efficiency. It is found that the use of high-dimensional model representation yields fairly accurate results with even less computational effort.

Deepak Sahu, Pradip Sarkar, Robin Davis

Dynamic Analysis of Roll-Pitch Coupled Motion of Ship With or Without Gain and Delayed Feedback Control

This paper presents the complex behavior of two-degree-of-freedom (2DOF) nonlinear coupled pitch-roll motions such as periodic, aperiodic, and chaotic solutions with or without active vibration control based on time-delayed feedback control under sinusoidal excitation. In the present study, the classical numerical integration technique has been applied to study the response behavior of coupled pitch-roll motion. A comprehensive numerical scheme based on numerical integration is applied to analyze all possible resonances of nonlinear couple pith-roll motion of the ship under time-delayed feedback. The numerical integration technique is applied to solve the nonlinear differential equation of two modes of a system model under sinusoidal harmonic excitation near the primary resonance, subharmonic resonance, combination resonance, internal resonance, and simultaneous resonance. The behavior of the system is studied using a frequency response curve and the different types of resonance cases (1) Ω ≅ ω1, (2) Ω ≅ 2ω1, ω2 ≅ 2ω1, (3) Ω ≅ ω1, ω1 ≅ ω2, (4) Ω ≅ ω1, ω2 ≅ 2ω1 are checked. The numerical simulation is carried out by numerical integration (NI) method and the results are presented graphically and are discussed. After the application of feedback control law, the frequency response plots have been obtained and control of response has been studied and compared. The different feedback control laws have been applied with either only displacement feedback with gain and delay or both displacement and velocity feedback with gain and delay. The gain and delay values are generally to be obtained from linear stability analysis. In the present study, the two-degree-of-freedom model is considered as weakly nonlinear coupled. The arbitrary gain and delay value have been used on the trial basis of different combinations of displacement and velocity gain-delay value to obtain the control of roll and pitch responses. The response stability of the 2DOF system is solved using MATLAB and Simulink toolbox. The frequency responses were analyzed using ode45 of MATLAB and Simulink of ode 45 and the results were compared. Characteristics of the solutions were also identified with the help of the phase plot diagram and Poincare map.

Reena Devi Ningombam, Atul Krishna Banik, Manoranjan Barik

Correlation Establishment of Compressive Strength and Bond Strength of Fly Ash Brick Masonry

Masonry is a heterogeneous material with the most complex, non-linear, anisotropic behaviour among all other construction materials (steel, concrete, etc.). Both masonry compressive strength and bond strength are two important parameters for structural design. A wide range of experimental studies considering two types of fly ash bricks and three grades of cement mortar is conducted to check the influence of masonry bond strength on its compressive strength. During the compressive strength test on stack bonded prisms, it is seen that when the brick–mortar bond strength is poor, the prism failure is also accompanied by a failure of the brick–mortar bond. The experimental result in the present study also reveals that with the increase in shear bond strength compressive strength increases indicating the existence of a correlation between these two important parameters. The correlation between compressive strength and shear bond strength of masonry is investigated and an analytical model is suggested accordingly.

Santosini Sahu, Peri Raghava Ravi Teja, Pradip Sarkar, Robin Davis

Mechanical Strength, Voids, and Sorptivity Evaluation of Copper Slag Based Standard Concrete

Management and proper employment of industrial waste is nowadays very essential in developing an unobjectionable environment. Using these waste products as a substitute to concrete preparing material is proving to be a better emerging solution for the problem. Copper slag is one such industrial waste, when used for a revolutionary concrete production (as an alternative to fine aggregate) provides good strength and durability. This paper deals with workability, compressive strength, split tensile strength, voids, water absorption, and sorptivity characteristic of concrete-incorporated copper slag. Copper replaces fine aggregate with five different percentages (0, 20, 40, 60, 80, and 100) to study slump value, mechanical strength, and percentage of voids, percentage, and rate of water absorption. Performance of copper slag incorporated concrete found to be superior to control specimen to produce concrete of good strength and durability.

Swetapadma Panda, Pradip Sarkar, Robin Davis

Application of Finite Element Modeling for Assessing the Fire Ratings of Beams

In recent times, occurrences of fire accidents in buildings have become more frequent. To avoid such situations, the effects of fire need to be incorporated into structural design and detailing. In this study, the structural behavior of fire-exposed flexural elements is assessed at elevated temperatures and fire rating is determined in accordance with different methods of Eurocode-2. Structural moment capacity is also evaluated by incorporating the procedure of simplified calculation methods present in Eurocode EN 1992-1-2:2004. In this study, Wickstorm’s method and transient thermal analysis using ANSYS are used for estimating temperatures in fire-exposed RCC members. Fire ratings obtained from the simplified calculation method and advanced calculation method of EN 1992-1-2:2004 is compared to fire ratings recommended in IS 456:2000 codal provisions.

Vivek Jain, Govardhan Bhatt

Effect of Shear Span to Depth Ratio in Strut-And-Tie Model on Deep Beam

In this paper, simply supported deep beam with different shear span to depth ratios are analyzed. The two different approaches are considered first as the elastic model of deep beam and Strut-and-Tie model. A study on strain behavior and flexural stress behavior with respect to shear span to depth ratio is considered. The load distribution in vertical tie mechanism and horizontal tie mechanism with respect to shear span to depth ratio is carried out and the graphs are plotted. Formulations of effectiveness factor in the Strut-and-Tie modeling are compared for different shear span to depth ratios on the deep beam. The FEM modeling of simply supported deep beam with different shear span to depth ratio is also computed using Finite Element Analysis Software “FEAST” in order to understand the stress flow path correctness. Based on all these parameters, some important conclusions are made.

Renu Sahu, U. K. Dewangan

Optimal Design Techniques of Composite Payload Adapter for a Typical Launch Vehicle

Composite materials made with the objective of getting a more desirable combination of properties are extensively used in weight-sensitive structures due to its very high strength to weight ratio and relatively high stiffness to weight ratio. A payload adapter forms an interface between the payload or the satellite and the launch vehicle core. The importance of weight savings in the payload adapter is that any reduction in its mass can help in a corresponding increase in the satellite mass since the sensitivity is 1:1. This is due to the positioning of the payload adapter near the satellite. This paper deals with the optimal design of a lightweight Composite Payload Adapter in three different configurations with a maximum mass advantage which at the same time should be able to withstand the loads acting on them during the flight. The design options studied were: monocoque, stringer-stiffened, and sandwich-structured construction. In monocoque construction, a metallic skinned structure made out of aluminium and also layered composite skinned structure made out of M55J/M18 prepreg laminates are considered for the study. The sandwich constructions are studied with metallic face sheets and layered composite face sheets in combination with a hexagonal aluminium honeycomb core. The study of stringer-stiffened construction was conducted by comparing the structure having the stringers and the shell made of aluminium with that made of M55J/M18 laminates. The optimum design out of these cases studied was arrived at. Static, buckling and free vibration analyses of all the cases were carried out using the general-purpose finite element software MSC. NASTRAN.

V. Pavithra, Gangadhar Ramtekkar

Nonlinear Static Analysis of a Rectangular Cable Supported Submerged Floating Tunnel (SFT) as an Alternate Crossing for Waterway

A buoyant-rectangular cable supported Submerged Floating Tunnel (SFT) can often be used as a waterway crossing even over the vast length and depth following the Archimedes’ principle. The interaction between buoyancy and self-weight controls the static and dynamic behavior of the tunnel. For SFT, weight to buoyancy ratio must be equal or less than one (W/B ≤ 1), so that the tunnel tube can float, where the cable curbs the upward thrust confirming its position, and hence 0.8565 is chosen. Here, SFT is modeled in ANSYS based on the environmental parameters of the Qian Dao Lake (China), where self-weight, hydro-static pressure, vehicular load, and water pressure to the tunnel are considered during nonlinear static analysis. Consequently, it has been observed that the deformations and stresses are in the permissible limit, where maximum equivalent strain exceeds the allowable limit due to its high slenderness, and the maximum strain occurred only at the cable joints.

Md. Hafizur Rahman, Chhavi Gupta

Nonlinear Finite Element Analysis of Plain Footing

Plain foundations are shallow foundations which are widely used in construction industry. In traditional analysis of plain footing, the finite element analysis is carried out as plain strain problems in different soil models. In the case of 3D problems, the combined effect of nonlinear behaviour of soil and soil-structure interaction under footing is not accounted for. In this paper, the nonlinear analysis of plain footing is performed by using 3D stress elements and considered the interaction between the soil surface and the bottom of the foundation, that is, the distribution of contact pressure under the plain footing along with the material and geometric nonlinearities. A three-dimensional model of the plain footing having dimensions 0.6 m x 0.6 m x 0.05 m, resting on very soft clay, is considered and the rigorous analysis of the same is performed. The finite element model of the plain footing is developed by using the popular package ABAQUS. The validation of the model is performed by making use of the results from an experimental study available in the literature. A parametric study is also carried out to asses the performance of the footing under the variations of four different soil parameters, viz, elastic modulus, Poisson’s ratio, friction angle and cohesion intercept. Although the elastic properties of the soil have no influence on the bearing capacity of the footing, this is demonstrated for purely of academic interests.

Rakhi Elizabeth Thankachan, Bennet Kuriakose, Jitin Jacob

Soil–Structure Interaction Analysis of Tall Steel Chimney Subjected to Wind Load

Chimneys are tall structures having phenomenal sensitivity to wind loads. Generally, computational analysis of tall structures is carried out without considering the effect of soil beneath, which in turn results in incorrect prediction when compared to the real response. This paper presents finite element modelling of a steel chimney on annular foundation subjected to wind load considering soil–structure interaction. The study reiterates the necessity of considering the effect of soil while reckoning the response of tall structures.

Anjaly Mohan, Binny Lizia Jose, Bennet Kuriakose

Investigation of the Suitability of Water Demand Studies as an Indicator of Incompatibility Between Binders and Superplasticizers

Use of superplasticizers (SP) in concrete production has advantages that are manifold, leading to improved performance in many characteristics including strength and durability. The use of SP ensures maximum workability with reduced water demand, heat of hydration, segregation, and bleeding. However, since most of the concrete mixtures used today included many additional ingredients especially in the binder phase, it is essential that the compatibility between ingredients and chemical admixtures is well established beforehand. In this study, the possibility of using a simple test such as the water demand variation with SP dosage, using Vicat’s apparatus, as an indicatory test to identify any incompatibility is explored. The experimental program consisted of studies on pastes composed of 2 brands of Portland Pozzolana Cement (PPC) with two major families of superplasticizers, viz., Sulphonated Naphthalene Formaldehyde (SNF), and Polycarboxylate Ether (PCE). Both SPs showed different trends in characteristics like water demand, workability, fluidity of paste, mixing time at the same SP dosage (solid content). PCE showed a trend of decrease in water demand whereas in case of SNF water demand decreased initially and later increased at slightly higher dosages of SP indicating that overdosing greatly affects the cement–superplasticizer interaction in SNF. The effect of the addition of more pozzolanic materials to fly ash based PPC, for increasing the sustainability potential was analyzed by replacing PPC with 5% and 10% of fly ash and Coconut Shell Ash (CSA). It was found that at different SP dosages, the water demand decreased considerably at initial dosages compared to the reference mix. The results from studies with SNF concluded that incompatibility exists irrespective of the cement brand. To understand the relation of incompatibility with a change in mixing method, hand mix was replaced by cake mixer, also different mixing pans were used and the graphs were compared. The experiment clarifies that although the trend of water demand–SP dosage graph (in percentage) remains the same, workability and water demand changed with the change in mixing. Though validation of these results has not been done with standard tests such as Marsh cone and mini-slump tests, the study leads to the conclusion that the water demand studies could be considered an indicative qualifier to identify compatibility issues and can be used complementing the standard tests which would provide quantitative evidence of the SP saturation dosage.

A. K. Swathy Krishna, T. K. Sreeranjini, P. L. Vijayakumari
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