Proceedings of the Canadian Society for Civil Engineering Annual Conference 2023, Volume 10

Inhaltsverzeichnis

1. Frontmatter

2. Efficient Seismic Fragility Assessment Through Active Learning and Gaussian Process Regression

   Chunxiao Ning, Yazhou Xie

   Abstract

   Seismic fragility models quantify the damage and collapse exceedance probabilities of civil engineering structures under varying levels of seismic hazards. Fragility assessment plays an important role in both probabilistic seismic risk assessment and performance-based seismic design. Developing accurate and robust seismic fragility models is computationally demanding, as numerous nonlinear time history analyses (NLTHAs) are needed to capture all sources of uncertainties embedded in earthquake loads, structural geometry, material properties, design details, etc. In this regard, this study leverages active learning (AL) and Gaussian process regression (GPR) to efficiently develop seismic fragility models without conducting exhaustive NLTHAs. In particular, the GPR predicts the mean and variance of structural responses conditioned on input features (i.e. structural parameters and seismic intensity measures), from which fragility curves are constructed by convolving the probabilistic seismic demand models with capacity limit state models. Furthermore, the AL algorithm recursively selects the optimal set of motion-structure samples to carry out the least number of NLTHAs for training against the GPR-based fragility model. The accuracy and efficiency of the proposed AL-GPR scheme are demonstrated using a benchmark highway bridge class. First, the GPR-based fragility model shows superior damage/failure exceedance probability inference when compared with conventional approaches. Besides, the seismic fragility model trained on a minimal subset of AL-selected NLTHAs achieves comparable performance as the original model using 1950 samples. This research develops an advanced machine learning technique to efficiently and reliably assess the seismic fragility of structures, which tackles one crucial computational challenge to facilitate high-resolution regional seismic risk assessment of existing structures and performance-based seismic design of new structures.

3. Nonlinear Axial Compressive Behavior of Concrete-Filled Filament-Wound GFRP Tubes

   Kraig Bates, Pedram Sadeghian

   Abstract

   Utilizing multidirectional filament-wound glass fiber-reinforced polymer (GFRP) tubes instead of uniaxial GFRP wraps as a confinement mechanism can be shown to promote a recognizable degree of both axial and circumferential resistance against the concrete core against applied axial loads. This composite system is recognized as concrete-filled GFRP tubes (CFFTs). For this study, the CFFTs axial compressive behavior is investigated using low strength concrete that is encased by thin-walled and thick-walled GFRP tubes with a multidirectional fiber orientation. A total of 10 CFFTs and 5 unconfined cylinders are produced using normal density concrete. The filament-wound GFRP tubes in consideration have an off-axis fiber orientation of ±55°, promoting significant biaxial resistance to concrete core deformation. The classical lamination theory is adopted to estimate the GFRP tube’s enhanced material properties. The CFFTs possess a notable degree of nonlinear biaxial behavior at higher axial loads, attributed to nonlinear characteristics associated with the GFRP tubes. A modified prediction model, originally proposed by Xie et al., is adopted to predict the CFFTs nonlinear stress–strain response to ultimate failure. The experimental results are compared to the model output to verify its accuracy.

4. Preliminary Investigation on the Compressive Strength of Built-Up Compression Members of the Original Champlain Bridge

   Morane Chloé Mefande Wack, Oudom Chhoeng, Hiroyuki Inamasu, Nicolas Boissonnade, Robert Tremblay

   Abstract

   This study describes a preliminary evaluation of the compressive resistance of built-up members used in steel trusses of an old long-span bridge. This study is part of the research and development programs on the deconstruction of the original Champlain bridge initiated by Jacques Cartier and Champlain Bridges Inc. (JCCBI). Finite element analysis was performed on 14 built-up truss member specimens to be extracted from the Champlain bridge to determine their compressive behaviour and ultimate strength under compression loading. The examined members are made of two face-to-face channels, or four angles connected by batten plates. The analyses accounted for material and geometric nonlinearities. Local and global geometric imperfections were also considered; however, residual stresses were not incorporated in this preliminary exploratory investigation. All members were assumed to be pinned at their ends to reflect the conditions that will be imposed in the planned experimental program. The compressive behaviour and ultimate capacities from the numerical simulations are compared with the predictions from the equations for built-up members that are provided in the 2020 AASHTO LRFD bridge Design Specifications in the U.S. The comparison shows a good correlation for most of the members examined. In the case of built-up members with slender elements, significant differences were observed between the numerical simulations and the code predictions, which is attributed to the fact that local buckling and its interaction with other buckling modes are not well addressed in current code provisions for this type of members.

5. Strength Evaluation of Early-Age Masonry Walls Subjected to Lateral Loads

   Ali Abasi, Ayan Sadhu, Bennett Banting

   Abstract

   Several international standards, such as ACI-530 and CSA-S304, were prepared to design fully cured masonry structures subjected to lateral loads safely. However, early-age masonry structures (i.e., within seven days after construction) are vulnerable to wind-induced lateral loads, and they do not attain the same strength and properties as fully cured masonry. According to the design codes, early-age masonry walls should be supported laterally using temporary bracing until they are integrated into other structural elements or the masonry assembly cures. On the other hand, since quality assurance testing does not begin until seven days after construction, there is no data providing information about the properties of early-age masonry. Therefore, designers are left to rely on engineering judgment to extrapolate the properties of early-age masonry to design temporary support systems for these walls. This gap inevitably results in inaccurately designed temporary bracing systems, which has resulted in the failure of several fresh masonry walls and can lead to injury or even death on jobsites. In this paper, a new test setup has been designed to monitor the behavior of full-scale early-age masonry walls subjected to uniformly distributed lateral loads, simulating wind loads. Several early-age masonry walls corresponding to different curing periods, including 5, 16, 72, 168 (7 days), and 672 h (28 days), have been tested and monitored, and the flexural tensile strength of the masonry walls has been investigated. The results show that the strength of early-age masonry walls during the early hours after construction is less than 5% of their full strength, and the curing time plays a vital role in the strength of the early-age masonry walls. Moreover, early-age masonry walls obtain almost 40 and 73% of their full strength during just the first 24 and 72 h of curing time, respectively. The tensile strength of the mortar governs the failure of the early-age masonry walls, and an abrupt failure happens during the tests.

6. A Universal Performance-Based Rating System for Existing Structures via Fuzzy Logic: A General Framework

   Sahand Salili, Ahmed Abdelmaksoud, Fadi Oudah

   Abstract

   The performance rating of an existing structure is critical in planning proper maintenance actions. Visual inspection is often used to assess the condition of existing structures because of its efficiency when assessing a large inventory of structures. Visual inspection is challenged by a high degree of uncertainty in the evaluation results and subjectivity in the method of assessment. In this study, Fuzzy logic is used to develop a novel universal performance-based rating (UPR) system to rate the performance of structures based on visual inspection data, considering uncertainties in site evaluations. The framework comprises of five main steps: (1) defining the performance criteria of the structure under assessment, (2) defining the material deterioration models, (3) using fuzzy logic principles to map the observed damage states into numerical values of material properties, (4) conducting fuzzy-numerical analysis to evaluate performance, and (5) drawing performance charts as the primary goal of the proposed technique. With the aid of these performance charts, inspectors can make more reliable decisions regarding the condition of the damaged structure, which ultimately leads to a better budget distribution for infrastructure maintenance from a more general perspective. For demonstration, a UPR system is developed to assess a simply supported beam based on visual inspection.

7. Comparison of Various Walking Load Models in Predicting the Dynamic Behavior of Lightweight Pedestrian Bridges

   Elyar Ghaffarian Dallali, Pampa Dey

   Abstract

   With the growing use of high-strength and lightweight materials for sustainable constructions, vibration serviceability often governs the design of such structures, specifically for pedestrian bridges under human-induced walking excitations. To better design lightweight pedestrian bridges, it is necessary to accurately predict human-induced excitations. To this end, the periodic moving force model has been highly accepted by the existing design codes around the world because of its simplicity of calculation. However, the capability of this modeling approach to realistically predict the vibration response of lightweight pedestrian bridges is debatable. More accurate modeling approaches have also been proposed in the literature based on human walking dynamics such as the mass–spring–damper and bi-pedal models that can capture the human–structure interaction phenomena. However, none of such models has been validated for lightweight pedestrian bridges. This study aims at evaluating these models for their capability in predicting the vibration response of lightweight bridges. In particular, the numerical responses have been estimated for the mass–spring–damper and the moving force models and compared with experimental observations from an aluminum pedestrian bridge under single-person walking loads. A comparison study between the performances of these two modeling approaches has also been undertaken to identify the better load model for lightweight pedestrian bridges. In the future, this study will be extended to other modern modeling approaches of walking loads as well as for crowd excitations including the human–structure interaction phenomena.

8. Viscous Damping and Energy Dissipation of Concrete Columns Reinforced with Hybrid Reinforcement Constituted of Steel Bars and GFRP Spiral and Cross Ties

   Anmol S. Srivastava, Girish N. Prajapati, Ahmed S. Farghaly, Brahim Benmokrane

   Abstract

   Steel bars in reinforced concrete structures are prone to corrosion causing loss of strength and energy dissipation capacity of the concrete structures. The problem of corrosion in civil infrastructure has encouraged research in new noncorrosive reinforcements such as glass fiber-reinforced polymer (GFRP) bars. GFRP bars have good corrosion resistance; however, it has a linear elastic stress–strain relationship which affects the energy dissipation capacity of a concrete structure subjected to simulated lateral cyclic loading. The present paper assesses the seismic response of concrete columns reinforced with steel longitudinal bars and confined with GFRP spiral and cross ties. Analytical studies were conducted on four full-scale 400 × 400 mm columns subjected to quasi-static lateral cyclic load. The variable parameters in the study were longitudinal bar size and spacing of GFRP spiral and cross tie. The viscous damping, energy dissipation capacity, and stiffness degradation were used to evaluate the performance of the concrete column. Outcome of this study shows that the energy dissipation capacity improved by reducing the spacing of GFRP spirals and cross ties. Further, the hysteresis viscous damping decreased with increase in the longitudinal bar size. Finally, simplified empirical equations are proposed to estimate viscous damping and energy dissipation capacity for the studied reinforced concrete columns.

9. Static Tests on T-Stiffener and Doubler Plate Reinforced Moment Connections with RHS Columns

   Rebecca Clahane, Kyle Tousignant

   Abstract

   Two beam-to-column connections for limited-ductility (Type LD) steel moment-resisting frames (MRFs) with rectangular hollow section (RHS) columns are investigated. The first connection is reinforced externally using T–T-stiffeners. The second contains top and bottom moment plates (designed for tension and compression) that are welded to a doubler plate reinforced RHS wall. This paper presents an initial comparison of the CSA S16:19 and AISC 341-16 design requirements for Type LD MRF and ordinary moment frame connections; rational design approaches for the two connections considered based on previous research; a summary of two large-scale, monotonic tests performed on the connections at Dalhousie University; and an evaluation of the strength, stiffness, and overall behaviour of each connection assembly.

10. Characterization of Fire Stations in Montreal for Seismic Risk Assessment

    Thomas Lessault, Ahmad Abo El Ezz, Marie-José Nollet

    Abstract

    A recent study by the Institute for Catastrophic Loss Reduction for fire following earthquake scenarios in Montreal has highlighted the importance of the assessment of the seismic vulnerability of fire stations in the city to better understanding their capacity to respond to potential fire ignitions following a large earthquake event. Moreover, such vulnerability assessment would provide needed information on their level of risk and guide plans for seismic retrofit to ensure their post-earthquake full functionality. This paper presents an investigation on the structural and non-structural characterization of exiting fire stations inventory in the city including geometrical parameters. The followed methodology included: collection of data from the city archives on the location and year of construction for each station, assessment of floor plans for geometric assessment, identification of main lateral load resisting system, and field visits and interviews with fire officials for the assessment of non-structural components that are essential for the functionality of stations. The inventoried stations were then classified into six main archetypes according to their service area scale, year of construction, construction material, lateral load resisting system, floor system, and presence of geometrical irregularities. The study revealed that 39% of stations were built before the introduction of minimal seismic provisions in the 1953 National building Code of Canada. Moreover, most of the stations contain unreinforced masonry walls either as part of the structural load-bearing system or as non-structural façade or partition walls. The study underscored the significance of improved understanding and assessment of seismic vulnerability of fire stations and the evaluation of corresponding impact on the fire department capacity to respond to post-earthquake fire events.

11. Performance of Wood Timber Covered Bridges Over the Last 150 Years

    Kenneth C. Crawford

    Abstract

    By looking at the performance of wood timber covered bridges over the past 150 years, the purpose of this paper is to explore the feasibility of designing and constructing a medium-span wood covered bridge capable of supporting commercial traffic and to build and preserve the bridge to have a service life comparable to the covered bridges built in the 1800s. Using the concepts and principles developed in the mid-1800s to construct covered wood bridges and their performance over the past 150 years, this paper proposes to use the same principles to develop, design, and construct modern covered wood bridges capable of transporting heavy vehicle traffic. The idea of using wood structural elements in the bridge offers the possibility of preserving and protecting the wood members to last an extended period of time. The issue with reinforced concrete (RC) bridges is the length of their service life which is typically considered to be about 75 years. RC bridges after 30 or 40 years often require major repair and rehabilitation, and replacement before 75 years. A modern wood bridge with proper protection can possibly last up to 150 years. The fact a wooden bridge, when properly protected, can last for an extended time is illustrated by the number of existing timber covered bridges across the United States and Canada. In Indiana alone, there are currently 98 extant covered bridges, many still in service, with their wood structural members in excellent condition. Based on this paper’s research and findings on covered bridge structures and their long service life, it is feasible a modern medium-span timber highway bridge can be fabricated, preserved, and placed into an extended service life for up to 150 years or more, well beyond the 75-year service life of typical RC highway bridges. One wood beam bridge concept is presented in this paper, with more concepts under consideration. Designing and building a timber bridge to meet AASHTO HL-93 vehicle loading to last many years is a real challenge and will take significant research. But building such a wood bridge may be possible.

12. An Improved Vehicle Scanning Method Based on Contact Point Response

    Premjeet Singh, Ayan Sadhu

    Abstract

    Contact point (CP) response of a passing vehicle can be used for the modal identification and condition assessment of bridges. CP response of a vehicle contains the input from bridge dynamics and is free from the vehicle suspension input or vehicle frequency that may overshadow the bridge modal frequencies. As the CP response is free from the vehicle frequency, the collected signal can provide a more accurate representation of the bridge response. Empirical mode decomposition (EMD) is utilized in this study to compare the performance of CP response with direct and indirect monitoring techniques. The measured CP data are processed through a signal decomposition tool, robust EMD (REMD), enhanced by a soft sifting stopping criterion. A numerical study is performed using the closed-form solutions of CP response to various realistic test scenarios including vehicle speed, measurement noise, and structural damage, on the performance of REMD. This study demonstrated the performance of REMD in signal decomposition, signal demodulation, and the estimation of the instantaneous amplitude and frequency. The advanced time–frequency analysis of the collected signal demonstrates pertinent information related to the bridge condition assessment to the stakeholders and decision-makers.

13. Governing Lateral Load on Tall Buildings in Canadian Regions

    Stephen Vasilopoulos, Kendra McTavish, Laura López Ramírez, Katrina Chong, Katrina Proulx, Ahmed Elshaer

    Abstract

    The design of tall buildings are typically governed by lateral loads, such as wind and earthquake. The tendency for a specific lateral load to govern building design varies based on the building characteristics, building height, and the location of the building. Generally, as building height increases perpetually, the design is governed by wind load. In contrast, earthquake load tends to govern design of structures of low to medium height, structures with elevated magnitude of story mass, and structures located in regions of high seismic activity. Geographic location plays an important role in the determination of both climatic and seismic loads, since certain zones across Canada may experience various combinations of the two natural hazards. There is a need to identify and map the governing lateral load (i.e., wind and earthquake) for use in preliminary design and city-scale assessment. This paper primarily aims to assess the impact that geographic location has in determining the governing lateral load of tall structures by conducting a parametric study of comparable building designs. Accordingly, the current study utilizes the finite element method (FEM) to create conceptual building designs based upon the Commonwealth Advisory Aeronautical Council (CAARC) building. The designs are performed based on the National Building Code of Canada (NBCC) and consist of four parameters: geographic location, building height, seismic site class, and lateral force-resisting system. The results provide a basis by which the design of a standard high-rise building varies in Canadian regions.

14. Performance of Insulating Honeycomb Paperboard Blocks

    Farida M. Marie, Aliaa A. Elaraby, Reen M. Aguib, Lara E. Moawad, Laila E. Sheta, Mayar M. Khairy, Seif A. Nazir, Mohamed Darwish, Khaled Nassar, Reham A. Khalifa, Mohamed A. Kamal, Mohamed N. Abou Zeid

    Abstract

    In a world of increasing levels of CO₂ emissions and environmental degradation, brick kilns used in the making of construction blocks are considered to have a high impact on the environment due to the growth in population and urbanization. Land pollution is also a main concern where the food quality of agricultural land is damaged by the copious quantities of waste materials made from brick kilns. Simultaneously, land cutting causes soil erosion because good quality soil is used in the making of high-quality blocks. The health of the workers, who make up an integral part of the industry’s manpower resources, is regarded as the most crucial concern. Aiming to shed light on climate change, saving waste, and green construction, the incorporation of honeycomb and corrugated sheets produced from flute cardboard with less cement, aggregates, sand, and water to produce a building block is the central focus of the work. The integration of flute cardboard into the production blocks has minimal environmental impact as its manufacture means a reduction of 60% in CO₂ and oil emissions (Abou-zeid et al, A proposed use of sound insulation systems (2019) [1]). Additionally, it is recyclable, biodegradable and saves prominent levels of energy. The study aims to produce more environmentally friendly building blocks by reducing Portland cement and replacing it with eco-friendly honeycomb paperboard. Experimental testing is implemented to compare the properties of honeycomb paperboard blocks to both solid and hollow blocks while ensuring better thermal and sound insulation and maintaining a suitable compressive strength. The tests that will be implemented include compressive strength, thermal and sound insulation, and water absorption. Hence, three mix ratios of different honeycomb thicknesses are prepared to achieve an adequate mix ratio between the honeycomb and concrete mix design. Upon choosing the most adequate mix ratio, two walls are conducted: one using market solid blocks and the other using the honeycomb paperboard blocks selected, and load-bearing test is conducted testing the load distribution and capacity the blocks can withstand.

15. Instrumentation and Monitoring of a Critical Aging Highway Culvert that is Approaching Failure

    Campbell Bryden, Greg Profit, Jared McGinn

    Abstract

    Highway culverts promote natural drainage, provide crossings of small-to-moderate width, and are critical structures within modern transportation networks. Culvert rehabilitations and/or replacements are inevitable as infrastructure ages, and owners are tasked with developing asset maintenance programs to ensure continued operation of transportation networks. Agencies may close a road while waiting for a culvert replacement or, as in this trial, may choose to monitor conditions and close the road if necessary. The subject of this study is the Lefurgey Brook Culvert located on NB11 near Campbellton NB; this structure consists of a corrugated steel plate arch culvert with 2.0 m width, 25.6 m length, and is buried beneath approximately 4.5 m of fill. This culvert is owned and operated by the NB Department of Transportation and Infrastructure (NBDTI), and the results of recent routine inspections revealed that the culvert is in very poor condition with observations including: severe deformation and reverse curvature along the pipe wall and invert, joint separations with water flowing behind the pipe wall, backfill visible at separated pipe joints, and corrosion of steel. The most severe conditions are observed at the inlet end, and erosion is present on the shoulder of NB11 near the inlet. Design of a replacement structure was initiated immediately and is scheduled for installation during summer 2023. For public safety and to provide continued operation of NB11 during the time leading up to replacement, an automated monitoring system was installed at the Lefurgey Brook Culvert. The monitoring system consists of a 25-m-long ShapeArray installed horizontally within the shoulder of NB11 near the inlet. The ShapeArray is connected to a Thread data acquisition system, which is configured for remote access using a cloud data hosting service. The purpose of this instrumentation system is to monitor vertical deformations above the culvert, and a “push notification” system is implemented to ensure that interested parties are notified immediately should excessive deformations be observed. Details of the instrumentation program and data collected during the first months of operation are described herein. If the trial is successful, NBDTI will implement this technology to monitor conditions at other failing culverts.

16. Torsional Performance of HSC Box Girders Reinforced with GFRP Bars

    Ibrahim Mostafa, Salaheldin Mousa, Hamdy M. Mohamed, Brahim Benmokrane

    Abstract

    The behavior of high-strength concrete (HSC) box girders reinforced with glass-fiber-reinforced polymers (GFRP) under pure torsional loading has not been addressed, so far. Three large-scale concrete box girders reinforced with GFRP bars and stirrups were cast and examined under pure torsional loading over a clear span of 2000 mm. The box girders measured 4000 mm long, 380 mm wide, 380 mm deep, and 100-mm wall thickness. The test parameters include the web reinforcement configuration (spirals vs. ties) and concrete strength (NSC vs. HSC). The test specimens included two girders constructed with NSC—one reinforced with GFRP continuous spirals and one with GFRP individual ties—and the last one with HSC and GFRP continuous spirals. The test results indicated that the specimen with HSC and spiral stirrups exhibited the highest pre-and-post-cracking torsional strength and stiffness compared to counterpart specimens with NSC and ties or spirals.

17. Interaction Diagram of Short Concrete Columns Reinforced with GFRP Rebars

    Alireza Sadat Hosseini, Pedram Sadeghian

    Abstract

    Glass fiber-reinforced polymer (GFRP) rebars have been gaining attention due to their relatively lower cost and corrosion-resistant properties. However, there has been a lack of research on their compression capacity, resulting in their limited use in compression members. Columns are usually subjected to axial load and bending moments due to load eccentricity caused by construction imperfections, accidental loads, or architectural requirements. Column interaction diagrams are used to represent the axial and flexural resistance of reinforced concrete columns, where the magnitude of load eccentricity can significantly affect the behavior of the column. This study aims to investigate the effect of considering the compressive strength of GFRP longitudinal rebars on the interaction diagram of GFRP-reinforced concrete columns and to determine what is lost when their contribution to load-bearing under compression is limited or neglected. Two commonly used stress–strain relationships of concrete in compression were employed, and the model was verified against existing literature. Comparative and parametric studies were conducted to improve understanding of the interaction diagrams. Limiting the compressive GFRP strain of rebars to 0.002 or neglecting their compressive strength resulted in a reduction of load-bearing capacity in the column by about 5% to 17%. It was also observed that the contribution of concrete mostly affects the belly point in the interaction diagram of the GFRP-RC short columns, and the location of the balance point in GFRP-RC columns does not necessarily lie at the belly point.

18. Buffeting Response of a Long-Suspension Bridge Considering the Effects of a Changing Climate

    Laurent Allard, Reda Snaiki

    Abstract

    With the continuous increase of the suspension bridge spans, the wind-induced vibrations will pose serious problems to the structural integrity and serviceability. Among the many vibration sources of long-span bridges, buffeting, which results from the impinging turbulence, affects the fatigue life of the bridge structure and might lead, when coupled with other wind-induced loads, to severe structural problems. With climate change, the buffeting-induced risk might significantly increase due to higher wind speeds and turbulence intensities. Therefore, it is important to assess the buffeting response under changing climate scenarios. In this study, the buffeting response of a single-span suspension bridge is investigated in the frequency domain under the worst-case climate scenario RCP 8.5 using the quasi-steady theory and the strip assumption. The performance-based wind engineering approach is implemented here to evaluate the risk values corresponding to several limit states. The suspension bridge is modeled based on the theory of continuous beams. The velocity fluctuations were generated based on the von Karman spectrum. The lateral, vertical, and torsional displacement response spectrums were generated. The simulation results indicated a significant increase in the buffeting response of a long-suspension bridge because of climate change.