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

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

This paper presents a numerical investigation of timber-to-timber connection with inclined self-tapping screws (STSs). This screw connection is designed for a panelized light wood frame gable roof. Panelized construction subdivides a building into several 2D elements, such as wall and floor panels. This construction method aids flexible design analogy to accommodate different architectural forms of building and simultaneously provides higher productivity in project delivery. However, panelized construction in North America is partially panelized due to the roof fabrication procedure. Currently, the roof production process is similar to the stick-built method. The roof structure typically consists of a series of triangulated trusses fabricated with dimension lumber with light-gauge steel plate connection. These triangulated trusses are often manufactured in a factory and brought to an offsite building prefabrication facility. The trusses are arranged on a platform according to the building plan, and sheathing is added to construct a roof module. Several roof modules are produced to build a complete house. Therefore, a relatively high transportation cost is observed in contrast to the wall and floor panel shipping. Moreover, the roof-building process is entirely manual. Consequently, the roof production line creates an imbalance in the overall building fabrication because of low productivity compared to other automated production lines. A holistic design approach is essential to improve roof production and move towards fully panelized construction. In this method, the gable roof structure is subdivided into several 2D panels, and the assembly is designed to incorporate the production and onsite installation factors. An efficient connection system is essential to connect the roof assembly and meet the structural requirements. This paper focuses on a self-tapping screw connection of the roof panel. This connection is assembled at the site to install the roof panel at the eave and support wall line. The connection test setup was designed following the ASTM D1761-12 to obtain the load–slip curve of the proposed screw connection under quasi-static monotonic load. A 3D solid finite element (FE) model of the connection was implemented in the ABAQUS software package and analysed under quasi-static loading conditions. Results of FE analysis show that the modelling approach can reasonably capture the expected performance of the proposed timber-to-timber joint.

The corrosion of reinforcing steel is the leading cause of deterioration of concrete structures, costing owners billions of dollars in repair and rehabilitation each year. As our infrastructure continues to age and experience further deterioration, fast and reliable condition assessment techniques are required. Until recently, condition assessments were limited to visual reviews, soundings, and concrete core extraction. Although these techniques provide valuable insight into the conditions of structures, the scope of data collection is limited. Numerous non-destructive technologies are now available for concrete condition assessments. Without causing damage to the structure, these technologies allow us to develop a greater understanding of the condition of the reinforcement. More complete, in-depth condition assessments are developed when non-destructive techniques are used in combination with visual assessment and concrete core extraction. An example of such a combined technique was used to assess a bridge deck in Atlantic Canada. A ground-penetrating radar (GPR) survey was carried out, a visual review of the structure was conducted, and concrete cores were extracted from key locations. The GPR survey data was used to map the areas of the deck which were most (and least) likely to be experiencing active corrosion. Concrete cores were extracted, and chloride profiles were measured. The core data was in excellent agreement with the GPR map, thereby validating the GPR data. The GPR survey produced a data set of over 6000 measurements. By validating this data with twelve cores, the map of deteriorated areas could be refined to a much greater resolution than a map produced with cores and soundings alone. Furthermore, the data collection was much faster than traditional assessment techniques, decreasing the disruption to traffic. The cost and duration of repair is reduced drastically with this combination of techniques, compared to traditional techniques. Furthermore, the map of deterioration can be used for future planning purposes; locations with minor chloride infiltration are identified before corrosion begins; and the membrane can be repaired at a fraction of the cost of concrete rehabilitation. By improving assessment techniques, we can prolong the life of ageing infrastructure and target repair funds to those structures most in need.

One of the areas that requires improvement in the precast concrete construction industry is the connections between elements which will address issues around inefficiency of the construction process in terms of accumulation of errors and speed and effort for alignment of elements such as walls and floors. The focus of this paper is on the preliminary strength tests of perforated steel tubes that will be used as an internal frame in precast concrete wall panels to accommodate a new bolted connection between precast walls. The connection will be self-aligning and ensure that strict tolerances are met during erection. The connection relies on an internal frame within the concrete wall panel made from perforated steel sections that the structural connection components bolt on to. Due to the location of the internal frame within the wall panel, it is important to understand whether it has some capacity to be also used as a partial replacement of traditional steel reinforcement. Therefore, four tube samples were tested in tension. While loading the samples, the corresponding strain was recorded throughout the testing using cameras and digital image correlation (DIC) software. Significant deformations, and consequently ultimate failure, was observed at the location of holes in these specimens. Strain distributions mapped onto the specimens using DIC process demonstrated large strain concentrations close to the bolt holes, due to significantly smaller net area compared to the gross areas between holes, specifically during the plastic response of the sections. The effective area of the specimens was calculated based on a known modulus of elasticity of 200 GPa and load and strain data. The average effective area of the four specimens was found to be 216 mm2 with a standard deviation of 8.7. This was found to be lower than both the gross cross-sectional area and net cross-sectional area of the specimens which were 377 mm2 and 258 mm2, respectively. The specimens had an average yield strength of 402 MPa and an average ultimate strength of 476 MPa based on the effective area.

Glass fibre-reinforced polymer (GFRP) rebars are an alternative to steel rebar for applications prone to corrosion. Limiting the maximum crack width of GFRP-reinforced concrete (RC) elements is one of the main criteria that governs their design. However, there is still limited knowledge of the cracking behaviour and crack width prediction of GFRP RC elements. This paper presents the results of a pilot study on the behaviour of six 1000 mm long reinforced concrete prisms tested under uniaxial tension. The aim of the study is to evaluate the crack development of ribbed GFRP RC structural members. The effects of different variables, such as the concrete prism cross-Sect. (90 × 90 mm and 150  × 150 mm), rebar type (steel and GFRP), and rebar diameter (16 and 19 mm), on the crack width and crack spacing were studied. The experimental results are compared with assumptions of available design codes and guidelines. Moreover, different approaches to predicting crack spacing and crack width are discussed. The results indicate that the reinforcement ratio has a significant influence on the load‒deformation response as well as crack spacing.

Modernity has introduced construction alternatives that could carry high loads such as reinforced concrete; however, such material is proven to be non-eco-friendly and expensive. However, these alternatives are not necessarily needed when constructing low-rise buildings. Hence, there is a need to study using different construction materials that are eco-friendlier and much more cost-effective compared to reinforced concrete. Within this study, a parametric study is performed on a two-story residential building. The study contains 25 different variations of the same building that feature five different dimensions. These 25 variations are divided into five conventional reinforced concrete structures representing the control group, and 20 eco-friendly structures made from combinations of wood, limestone, and compressed earth blocks. Following the modeling and analysis phase, the results obtained are compared to highlight the most economically-sound option for each range of dimensions. In addition, the total costs and carbon emissions of the eco-friendly models are compared with that of the commonly used reinforced concrete control group, all while delivering cost per area values for the most economical models, and the carbon emissions per area.

Visual inspection is the primary method for preliminary fire damage assessment; however, its reliability is questionable. Not only are inspection results highly subjective to the inspector’s judgment, but also, the results do not directly indicate the reduction in structural performance (e.g., gravity load capacity, lateral load capacity, deflection, etc.). Thus, this study proposes a new post-fire performance rating (PF-PR) system using fuzzy logic principles. The PF-PR system has five modules, including (1) the “Performance criteria” used as the basis for assessment, (2) the “Material damage models” which predict the reduction in material properties with fire damage (e.g., reduction in concrete strength and steel yield strength), (3) the “Fuzzy logic model” which maps subjective visual observations of fire damage into quantitative ranges of heating temperatures and material properties reductions, (4) the “Fuzzy-numerical analysis” which uses the material properties reductions as an input to a numerical model that evaluates the performance, and (5) the “Performance charts” which are the end-product of the framework and visual representations of the analysis results. These performance charts can support inspectors in mapping the findings of visual inspection (e.g., linguistic descriptions of fire damage) into quantitative structural performance measures. Not only would the proposed PF-PR system increase the reliability of visual inspections, but it would also allow stakeholders to reliably compare between different post-fire actions (e.g., repair or replace) from an economic perspective. The development of the PF-PR system is demonstrated for a case study of a reinforced concrete beam.

Susceptibility of the transportation system, namely the coastal bridges, to wave-induced damages has been demonstrated in past hurricane and tsunami events. With the rapid change of climate, extreme weather events are becoming more frequent and intense. It is imperative now that the failure mechanism be assessed to propose retrofitting of existing coastal bridges as well as new designs. This paper presents a comprehensive framework for the fragility and resilience assessment of coastal bridges exposed to extreme wave-induced loads. The analysis is demonstrated on a three-span reinforced concrete I-girder coastal bridge with circular piers. Intensity parameters chosen for this study are wave period, wave height and still water elevation. This numerical study is done in OpenSees, where the component-level fragility curves are generated using the multiple stripe analysis method. The system resiliency generated via the assumption of a series connection between the bridge components reveals that the bearing elements are the most vulnerable among the other bridge components studied when the waves do not reach the deck level. The proposed framework could be applied to assess the resiliency of other bridge types by adjusting the model parameters. This paper could help in developing design guidelines to improve the resistance of coastal bridges toward future extreme weather events.

The increase in demand for smart buildings has required engineers to produce innovative structural members that better facilitate the hardware and software connectivity intrinsic to smart buildings. An example of these innovative members is the Intelligent Structural Panel (ISP), developed by Stephenson Engineering Inc., Toronto, Ontario, to be used as a flooring system in smart buildings. The ISP presents a new approach to achieving a sandwich panel system. This paper aims at examining the flexural behaviour of this panel. The paper starts by providing details about two validation cases, chosen to ensure that the utilized finite element modelling technique can predict the deformation behaviour as well as all potential failure modes of the panel. A simple approach to predict weld failure was adopted and validated. Then, an ISP panel, consisting of top and bottom 6 mm plates separated by 25 mm-diameter studs, was modelled and analysed. The panel was examined considering service loads and factored loads. Then, the load was incrementally increased until one of the panel components failed. Results of the numerical model show that the ISP panel can be designed to achieve the serviceability and strength design criteria.

This paper presents a numerical evaluation of the CSA S16 design requirements for rectangular hollow section (RHS) members with slender elements. A total of 385 nonlinear finite-element models (342 compression members and 43 flexural members), validated from experimental results obtained in the literature, were developed. Parametric studies were performed to investigate the effect of key parameters on the nominal resistance. Reliability analyses were conducted to determine the inherent safety indices which are compared, herein, to the target reliability index outlined in CSA S16. Results show that the design method for Class 4 RHS compression members in CSA S16 Clause 13.3.4 is over-conservative. The predominant design method for Class 4 RHS flexural members in CSA S16 Clause 13.5 is also conservative, but by a lesser margin.

As we strive to make better use of our built heritage in a more sustainable and energy efficient future, it becomes critical to understand the materials, construction methodologies, and building standards of the past. The longstanding solution to construction was to demolish the old and construct anew, using the most current materials and methodologies. This resulted in lost knowledge of traditional practices and construction techniques. With the onset of sustainable design, and the drive to protect our environment and its resources, the construction industry and building owners began to look at ways to adapt and reuse our existing built heritage. Over 50% of construction projects today involve adaptive reuse. Determining how to blend contemporary codes, standards, materials, and construction methodologies, with those of our historic infrastructure poses a challenge. Schooling in general does not teach design, construction methodologies, and comprehension of historic materials. It is only recently that Carleton University and Algonquin College in Ottawa offer courses in Conservation Design and Construction to address this issue. Failure to fully conserve masonry, and understand how it performs, prior to reinforcing the masonry for current loading requirements, use of incompatible construction materials and structural solutions such as use of overly strong mortars, reinforcement of masonry using steel frames or concrete, reinforcing original timber structures without considering the entire strength of this timber, result in excessive costs, increased risk of material deterioration and structural damage over time. Striving for Net Zero, without an in-depth understanding of the historic material composition and construction systems, will lead to decay and damage to existing building envelopes in very short order. The solution is simple. A better understanding of historic structures, materials used, construction techniques, and Codes and Standards under which they were built provides the design consultants and contractors with a more compatible and efficient way to achieve our goal of Net Zero, without destroying our existing built heritage.

Earthquake-induced damage is inevitable in conventional lateral load-resisting systems, such as moment-resisting frames and shear walls. As an alternative solution, buildings can be designed to limit the damage to be concentrated on those members that can easily be replaced to ensure rapid recovery after seismic events. One of those systems that can provide this possibility is the self-centering (SC) system. Self-centering steel plate shear walls (SC-SPSWs) consist of thin steel infill web plates, boundary elements, and horizontal post-tensioned (PT) cables. PT cables can provide self-centering capability in the beam–column connection and allow beams to rock about their flanges and return the structure to its original position after seismic events. In this paper, an analytical study is performed to assess the seismic response of the two-story SC-SPSW. Non-linear seismic analyses of a two-story SC-SPSW and a two-story conventional SPSW are conducted for a set of near-field and far-field ground motions. Seismic demand parameters (maximum inter-story drift and residual drift) are obtained for the two selected SPSW systems; seismic analyses show that the SC-SPSW system experiences lower values of residual drift compared to the conventional SPSW, and an obvious increase is observed in seismic demand parameters as the excitation changed from far-field to near-fault. A parametric study is also conducted in order to identify the effect of infill plate thickness and the post-tension force on seismic demand parameters. Results indicate that increasing the web plate thickness contributes to a decrease in the peak inter-story drift, and increasing the initial PT force reduces the residual inter-story drift.

This paper presents an artificial neural network-based metamodel for extracting the inelastic cyclic response of steel hollow structural section braces that are part of concentrically braced frames when subjected to earthquake ground motions. The proposed model constructed using the bidirectional long short-term memory (BiLSTM) algorithm is intended to predict the inelastic cyclic response of steel braces, namely the brace axial force, based on the input axial displacement and out-of-plane displacement signals. The architecture of the proposed metamodel is first described. The validity of the model is then tested when the brace is subjected to a set of displacement signals obtained from numerical nonlinear time-history analyses. The preliminary results confirm that the proposed model has the potential to predict the complex hysteresis response of steel braces, involving tensile yielding and compressive buckling.

Aluminum can be successfully used as a structural material as it has numerous positive attributes such as high strength-to-weight ratio, excellent corrosion resistance, and environmental benefits. The current aluminum design provisions are based on simplified approach that does not efficiently consider the effect of strain hardening, local instabilities, and heat reduced properties of aluminum. This results in over-conservative designs which are not desirable from a cost standpoint. Hence, an optimized design approach is needed for accurately predicting the resistance of aluminum sections that can ensure the full economic benefits of having aluminum as a construction material for civil infrastructure. In this study, an attempt has been made to develop an alternative design approach for aluminum I-sections, based on the principles of Overall Interaction Concept (O.I.C.). This O.I.C.-based design approach helps us obtain precise and consistent estimation of buckling resistance as it relies upon the interaction between resistance and stability and considers geometrical and material imperfections in design. In this study, a finite element-based numerical model is developed in Abaqus software to predict the resistance of aluminum I-shaped cross sections. Extensive numerical parametric studies have also been performed to study the effect of geometries (size and thickness of section), alloys, and load cases on the value of resistance. Using the results from parametric studies (nearly 4500 simulations), O.I.C.-based design proposals have then been formulated to obtain the local resistance of extruded and welded aluminum I-sections. Finally, the estimated resistance from the O.I.C.-based design approach has been compared to that from existing design standards. It is found that the O.I.C.-based design proposals are more accurate than current design standards.

An innovative braced frame system is proposed to develop nonlinear elastic self-centring response for low-rise steel building structures for which enhanced seismic performance is required. The system comprises an inverted-V-bracing with brace-to-beam connections at the first level that are detailed to transmit compression loads by direct bearing and open under tension load. Energy is dissipated by friction upon gap opening and closing in the connections. This behaviour intentionally reduces the stiffness of the first storey that acts similar to a base isolation system for the building. V-braces connected to the floor beams are also provided in the first storey to develop sufficient effective stiffness upon activation of the inverted-V-braced frame nonlinear response. This new system is first described, together with the equations that can be used to calculate the first-storey effective period and equivalent viscous damping properties that are needed to control the building lateral displacements. The system is then used for two- and three-storey buildings located in Montreal, QC, and Vancouver, BC. Nonlinear response history analyses are then performed to examine its seismic response under design level ground motions. The results show that the system can exhibit enhanced seismic performance in terms of peak lateral displacements and peak horizontal floor and roof accelerations, with no structural damage nor residual deformation. This exploratory study also shows that peak lateral displacements can be reliably predicted using the simple single-mode method for base isolation systems.

Past earthquakes in different countries have produced many examples of lightweight buildings with significant drifts and subsequent damage at the first-story level. Seismic isolation systems have been proven effective in the protection of buildings against earthquakes by reducing base shears in structures. This paper presents details of different types of seismic isolation systems for lightweight buildings. They are characterized by lower lateral stiffness compared to classical elastomeric isolators. This feature enables them to be used for isolating lightweight structures. The lower lateral stiffness guarantees the attainment of longer natural periods of vibration in lightweight structures. An analytical model representative of the device is developed and used in numerical investigation. A four-story woodframe building model is used to examine its usefulness in lightweight buildings. Effectiveness of the proposed concept is demonstrated through numerical analysis.