Proceedings of the Canadian Society for Civil Engineering Annual Conference 2024, Volume 11

Ultra-High Performance Concrete (UHPC) is an increasingly popular material for bridge design due to its high compressive strength, durability, and fast curing time. UHPC has been used in structural applications for over a decade, mainly as field-cast material to connect prefabricated concrete elements. However, not every structure needs a full replacement. In most scenarios, the concrete decks are the most vulnerable component of the structure that needs replacing, mainly due to the impact of chloride ions within the deck due to typical de-icing methods. Historically, typical deck repair methods do not address the underlining issues or prevent such repairs from reoccurring. UHPC overlays can extend the service life of bridge decks, including long-span bridge decks, with significantly less traffic disruption and lower life cycle costs versus deck replacements or other overlays. This paper will discuss key elements to identifying appropriate bridge structures for a UHPC overlay, discuss the latest construction practices, and provide further inputs on the structural strengthening of bridge decks using UHPC.

Adjacent precast girders are a common choice for small and medium span bridges. Many states, provinces, rail operators, and jurisdictions have their own standard type girders for different spans that are suitable for their respective load conditions. Construction using adjacent precast girders can take several forms. For example, having a composite or non-composite topping or not having a topping at all. Girders can be connected transversely via steel rods, shear keys, post-tensioning or a combination of these or none at all. In this paper, we review some of the different configurations of adjacent girders used by jurisdictions and operators in North America discussing different considerations for the durability, constructability, analysis, and design. We will explore the effects of the different types of connections between the girders on their durability, constructability, and load transfer capability. Finally, we look at the analysis of adjacent girders with transverse post-tensioning and some considerations for design.

Reinforced concrete masonry, as the primary lateral load resisting system, is on the rise in North America due to its effective structural capacity, speed of construction and absence of formwork. Fully grouted reinforced masonry shear walls (FG RMSWs) have proved to satisfy ductility demands and withstand moderate-to-high earthquake loads. In contrast, partially grouted reinforced masonry shear walls (PG RMSWs) provide a more economical option for low-to-moderate seismic zones. However, the collapse probability of the latter has not been assessed as thoroughly as the former. Collapse probability refers to a structure’s likelihood to collapse in relation to a given intensity measure. This study aims to evaluate the collapse probability of rectangular PG RMSWs as compared to that of FG RMSWs in moderate seismic zones. Two masonry shear walls were designed according to the NBCC 2020. These walls are a part of a three-storey archetype residential building in Montreal, Canada. One wall was partially grouted, and the other was fully grouted. However, both walls were designed to withstand the same lateral loads. The numerical models of these two walls were developed using the software, Extreme Loading for Structures (ELS). The modeled walls were subjected to incremental dynamic analysis (IDA) using nonlinear time-history analysis with pre-recorded earthquake ground motions. The collapse probability was computed by cumulative distribution of the IDA curves. The results showed that the collapse probability of the PG RMSW was at most 15% higher than its FG RMSW counterpart. However, the PG RMSW would require 40% less material to construct. Therefore, PG RMSWs may be a viable economic alternative to FG RMSWs, while maintaining adequate seismic performance levels.

R.V. Anderson Associates Limited (RVA) is working with Noventa Energy Partners (Noventa) and Bird Construction (Bird) on the Toronto Western Hospital (TWH) Wastewater Energy Transfer (WET) Project. Once complete, it is believed that it will be the world’s largest operating WET system. Over the next 30 years, the project’s goals are to supply 1.8 billion kilowatt-hours of energy to heat and cool TWH. The project site is located adjacent to TWH at the intersection of Dundas Street and Bathurst Street in Toronto, Ontario. RVA is responsible for the design of two major structures on the project: the Energy Transfer Station (ETS) Building and the Wet Well (WW) shaft. The ETS is a multi-storey structural steel building constructed inside the shell of an existing pre-cast concrete and masonry building (formerly a bank). A significant underpinning operation of the existing building was completed to create the additional space required to accommodate the heavy process/mechanical equipment and piping. RVA designed the new internal structure to resist temporary loads from construction sequencing, permanent loads from the existing building and proposed equipment, and future loads from the upcoming phases of the project. The WW shaft is a cast-in-place reinforced concrete structure 9.5 m in diameter and 39 m below grade within both overburden soil and shale bedrock. The shaft is used to capture and return raw sewer flows from the City of Toronto’s existing Mid-Toronto Interceptor Sewer via two (2) new diversion and return tunnel connections deep within the rock. RVA designed the WW to accommodate process mechanical equipment (ex. screens, pumps, and valves), and operations infrastructure including two PVC vortex drop structures, substantial piping, maintenance platforms, and internal concrete wingwall and chamber structures. This paper summarizes various components of the structural design for the ETS building and WW shaft. A primary focus is on design challenges and the unique solutions that were used.

Lap splicing is the most common and cost-efficient method for connecting bars in GFRP-reinforced concrete structures. However, there is a lack of knowledge regarding the bond behavior of high-modulus GFRP bars in concrete. The present study aims to fill this gap by investigating the bond strength of lap-spliced high-modulus GFRP bars in concrete. These new-generation GFRP bars have a modulus of elasticity of up to 65 GPa and an ultimate tensile strength of up to 1400 MPa. Three large-scale splice beam tests, with a rectangular cross-section of 300 mm × 450 mm and a length of 5200 mm, varying splice lengths (28, 38, and 45 \(d_{{\text{b}}}\)), were designed to evaluate predictions of bond strength for North American design codes. Results show a nonlinear decrease in bond strength by 14.7 and 17.7% with a 36 and 60% increase in splice length, attributed to uneven bond stress distribution. On the other hand, these increases in splice length led to an increase in the splice strength by 17.7% and 31.8%, respectively. ACI 440.11-22 provides the most accurate predictions, showing an average test-to-prediction ratio of 1.03, while CSA S806-12 and CSA S6-19 overestimate with average test-to-prediction ratios of 0.84 and 0.57, respectively. In the latest Canadian Highway Bridge Design Code (CSA S6-25), the revised factor for GFRP-to-steel bond strength improves predictions with a test-to-prediction ratio of 0.89. However, Canadian codes generally over-predict bond strength, particularly by increasing the splice length to bar diameter ratio, neglecting the nonlinear bond stress distribution along the embedment length.

Precast, prestressed hollow-core slabs (HCS) are widely used in buildings since they offer an economical solution for a floor or roof system, especially those with large spans due to the reduced weight. Reinforcing bar connections are commonly used to connect these HCS to the building structure. These connections serve as structural integrity reinforcing ties to avoid floor displacements under lateral loads. This paper investigates the performance of reinforcing bar connections of HCS to supporting masonry walls used in Western Canada. These connections involve placing a 10 M, L-shaped steel reinforcing connection bar in grouted shear keys between HCS segments from one end, while the other end is wrapped behind 15 M vertical wall reinforcement. The parameter included in this paper is the location of the HCS in a 10-storey building: 5th floor or 10th floor (roof) with parapet. Two full-scale specimens were tested under monotonic in-plane tension forces until failure. The HCS segments, measuring 1220 × 1220 × 203 mm were supported on a 3990-mm long masonry wall with 76-mm seating/bearing length. The results showed that the connection bar satisfied the requirements of North American codes for three storeys or more. Additionally, it was found that the floors on top of the slab enhance the capacity of the connection. These findings provide valuable insights for the construction industry, ensuring safer, and code-compliant practices in using HCS in building structures.

Climate change has been increasing at an alarming rate during the last few decades. According to recent studies, Canada's average temperature over land has risen by 1.7 °C in the last 50 years. Reusing materials from old masonry building can reduce the waste and help mitigate the effect of climate changes in Eastern Canada. Construction, renovation, and demolition (CRD) is considered Canada’s largest waste stream with over 80% of solid wastes. This paper presents a preliminary study that quantifies both the mechanical and environmental properties for several types of old and new local clay bricks. Old bricks were retrieved from deconstructed buildings in Montreal (Quebec) that are dated to the nineteenth century. The new bricks used in this study are instead the most common types used in Canada’s construction nowadays. Several batches of old and new bricks underwent the same procedures of testing to ensure fair comparisons among all the samples. The mechanical characterization included destructive and non-destructive testing to assess the compressive and flexural strength of each brick. Tests performed comprised uniaxial compression, ultrasonic pulse velocity (UPV), and three point bending on both bricks and smaller prisms to investigate size effects. On the other hand, the environmental characterization included two pass/fail tests that are presently adopted by the Canadian Standard Association’s CSA-A82 to assess freeze and thaw resistance, namely 50 cycle-long freeze–thaw tests and a much faster 24-h absorption test followed by a 5-h boiling to obtain the water absorption ratio. Results are presented and compared for different samples and considerations are made for reusing such masonry products in building alterations, alongside some key limitations that our tests highlighted.

Recently, a novel experiment explored the possibility of employing low-rise arch masonry walls to resist earth pressure. The introduction of this innovative system aims to mitigate the “snap-through” failure characteristic inherent in conventional planar retaining walls. The authors established that the idea could work but did not study the influence of any of the parameters involved. To begin to overcome this limitation, four masonry arch walls were constructed using half-scale concrete blocks and modular cored bricks. The test walls had a span of 2 m and two different heights, 1 and 2 m. The arches had an equivalent span-to-rise ratio of 0.17. The walls were built on a concrete base, and the arches were cemented to the base with a mortar joint. The arches were subjected to soil pressure and surcharge load: displacements and strains were measured. The walls effectively exhibited arch action under soil pressure, with deflections of less than 1 mm. The brick wall showcased a notable arching phenomenon, exhibiting a slightly rigid reaction in contrast to the hollow block wall. The walls demonstrated a marginal rise in radial deflection corresponding to increasing elevation.

This paper presents an experimental study on the mechanical properties of the helically deformed glass fiber-reinforced polymer (GFRP) bars. The mechanical properties were determined through tensile, transverse shear, apparent horizontal shear, and pullout tests. The GFRP bars were manufactured using high resistant fiberglass embedded in a vinyl ester resin. The tested bars featured a helically deformed surface. Two bar sizes (#4 and #7) are selected in this investigation. The tensile properties of the GFRP bars met the Grade III classification in the CSA S807-19 specification, based on modulus of elasticity greater than 60 GPa. The bond between the GFRP bar and concrete is considered a critical factor that influences the structure’s behavior. The results showed that the bond strength of the tested GFRP bars was above the minimum requirements in CSA S807-19. Additionally, the tested GFRP bars satisfied the minimum limits of transverse shear, and horizontal shear strength as per CSA S807-19. Furthermore, the paper discusses the practical application of GFRP in concrete-face rockfill dam and other projects.

Buildings’ operational and embodied environments are responsible for a large portion of global greenhouse gas emissions. To reduce embodied carbon, eco-friendly materials and structural optimization are crucial. From a sustainability point of view, timber is considered one of the preferred material. Currently, mass timber building construction is experiencing a surge in North America and Europe. However, mass timber systems are generally more costly, compared to conventional systems built with other common structural materials. Structural design optimization can help in this regard and promote the construction of this sustainable alternative, to traditional systems. The current research is developing a method of optimizing glue-laminated timber (glulam) beam design through the use of reinforcement learning (RL). RL is a branch of machine learning where the agent interacts with an environment and learns through trial and error. Herein, the agent will take actions by picking glulam beams with a defined range of sizes, species and grades, and conducting the necessary design checks as per Canadian timber design standard, CSA O86-19. For the action taken, the agent receives rewards. The ultimate objective of the agent is to maximize the reward by minimizing the material cost. An RL agent, called the Proximal Policy Optimization algorithm, is trained to design the beam. It is found that the agent successfully designs the beam and minimizes the cost for a given beam length and loading condition.

Ensuring proper anchorage of slab reinforcement in slab-column edge connections is essential because of the interruption in the slab continuity. Meanwhile, glass fibre-reinforced polymer (GFRP) bars have emerged as an effective alternative to traditional steel reinforcement, offering a durable solution to the problem of corrosion in reinforced concrete (RC) structures. However, the provisions for reinforcement anchorage, particularly GFRP, introduce detailing challenges due to the required development length. Therefore, GFRP headed-end bars were developed to provide better anchorage between concrete and GFRP reinforcement. Two full-scale isolated slab-column edge connections reinforced with GFRP headed-end bars were constructed and tested to failure under a combination of gravity loads and unbalanced moments. The slabs had dimensions of 2800 × 1550 × 200 mm and were connected to a column stub measuring 300 × 300 mm, which projected 1000 mm top and bottom of the slab surface. The main test parameter was the flexural reinforcement ratio (0.9 or 1.8%). Both slab-column connections were subjected to the same moment-to-shear ratio of 0.4 m. The performance of the connections was evaluated in terms of capacity, mode of failure, deflections, and strains in both concrete and reinforcement. The behaviour of test specimens was compared with slab-column connections reinforced with GFRP bent bars from the literature. It was demonstrated that the connection constructed with GFRP headed-end bars as flexural reinforcement behaved similarly to its counterpart with bent bars. Moreover, an increase in the reinforcement ratio led to enhanced axial load capacity and improved post-cracking stiffness of the connection.

Z-Modular has recently introduced an innovative construction method known as the VectorBloc modular construction system. The VectorBloc connector plays an integral role in this system, and it is necessary to assess its performance across a range of structural scenarios. The registration pin is a critical component of this connector, designed for module lifting during the installation process. This paper highlights the outcomes of the experimental tests conducted on different iterations of the registration pin connections, totaling 36 connection specimens. Three parameters were considered: thickness of the lifting plate, the thread size (threads per inch—TPI) of the registration pin and the loading angle. Various failure modes were observed during these tests, including weld or shackle ruptures. However, thread stripping emerged as the most common one. The test results indicate that a thicker lifting plate and a smaller TPI value (coarser threads) on the registration pin threads enhance connection capacity (lifting). An increase in the loading angle, on the other hand, reduces the connection capacity. While several standards, such as ASME B1.1 [1], ISO/TR 16224 [2], and BS 3580 [3], offer equations for evaluating thread capacity at a zero-loading angle, there are no existing design equations for accurately determining the lifting capacity when the load is applied at an angle to the pin connection. This paper investigated the impact of the loading angle on thread resistance and, consequently, load-carrying capacity when various design parameters are changed.

Bridges are subjected to cyclic loading during their lifetime. Such cyclic loads can cause fatigue failures in the bridge structure in places with high stress concentration. One of such areas where the stress concentration can be quite high is in the connections. There are mainly two ways of joining steel members, one is by bolting and the other is by welding. When bridges are connected by bolting, during the working life of a bridge, it is expected that any bolted connection may eventually become a bearing-type bolted connection even if it was originally designed to be slip-critical. So, because of this bearing condition, high stresses are created and fatigue failure of the connections are more likely to originate from spots where the bolt bear against the plates or other parts of the connection. Therefore, it is necessary to understand the factors that contribute to increased stress concentration because then we can design bridge connections to avoid or reduce the stress concentration and hence increase the fatigue life of such connections. We can also use the stress concentration to predict the remaining life of bridge connections. So, this research investigated the predictors of the stress concentration factor and fatigue life of a bridge connection using machine learning (ML) algorithms. The dataset used was from testing of several bolted connections, and it contained a total of 31 instances. From the ML models, it was observed that parameters such as the stagger, and the gage distance were predictors of the stress concentration and that the stress concentration can be used to predict the fatigue life of such bolted bridge connection. Furthermore, the research also investigated the best ML algorithm for predicting the stress concentration for such small dataset.

This paper proposes both detailed and simplified approaches for modeling the base of cross-laminated timber (CLT) balloon-type walls. The timber at the base of CLT balloon-type walls is susceptible to delaminating and crushing due to the relatively high overturning moment demand under seismic or wind loads, especially in mid- to high-rise buildings. This complex nonlinear behavior at the base can significantly affect the wall’s performance under lateral loads and alter the demands on wall connections. Therefore, developing accurate models to capture the complex behavior at the base of rocking CLT walls is crucial. To achieve this, a detailed model of rocking CLT walls is developed in the ABAQUS software. Subsequently, a parametric study is carried out to investigate the effects of various parameters on responses, including (a) wall aspect ratio, (b) axial load, (c) wall thickness, and (c) hold-down strength. Pushover analyses are conducted to study the effects of these parameters on the overall base shear-top displacement curve, the variation in the base compression length, and the distribution of plasticity at the base of the wall. Following this, a simplified model is developed in the OpenSees software, which is more computationally efficient for future nonlinear time history analyses. The results demonstrate that the simplified model can accurately capture the local and global response of CLT rocking walls with acceptable accuracy.

This study aims to propose a reliability-based framework for analyzing the effect of truck platooning on bridge substructures. To achieve this purpose, the dynamic truck platooning–bridge interaction model was developed to calculate the dynamic load allowance (DLA) under varying truck platooning configurations and road conditions. The probabilistic model for DLAs was established based on numerical results. Meanwhile, the finite element model for the bridge pile shaft, considering the uncertainty of surrounding soil, was created for obtaining the probabilistic load capacity model. Then, Monte Carlo sampling method was employed to calculate the pile shaft reliability index using the developed load demand and capacity models. The effects of truck velocity, inter-truck spacing, number of trucks, and road conditions on the pile shaft performance at serviceability limit state were discussed. The results showed that the pile shaft performance could be negatively affected due to the dynamic impact of truck platooning. The number of trucks and inter-truck spacing should be limited to reduce the axial loads sustained by the pile shaft. Poor road conditions could significantly increase the dynamic response of bridges under truck platooning impacts, thus leading to considerable reduction in the pile shaft reliability.

The advancement of connected and autonomous vehicle technology has enabled the formation of truck platoons, where two or more trucks travel closely and at high speeds. While truck platooning offers fuel savings and increases road efficiency, it raises concerns about the potentially higher load effects it places on existing bridges than what they were designed to withstand. Previous research has predominantly focused on the structural safety aspect of truck platooning's impact on bridges, with limited attention given to evaluating its effect on the serviceability limit state performance of bridges. This study aims to address this gap by investigating the impact of truck platooning on the serviceability of prestressed concrete bridges. A set of bridge archetypes, varying in span lengths and girder spacings, are considered in such investigation. Through probabilistic models that account for load effects and structural resistance, the reliability indices are determined for these bridges under assorted truck platoon configurations. The impact of truck platooning is then assessed by comparing the bridges’ reliability when subjected to platoon loads against the predefined target reliability or the reliability under standard traffic loads, the latter determined from statistical analysis of Weigh-in-Motion data. The results emphasize that certain platoon configurations may satisfy the ultimate limit state requirements but fail to meet those of the serviceability limit state. This underscores the essential need to evaluate bridges against different limit states to ensure their structural integrity is preserved when subjected to truck platoon loads.

The ability to retrofit and repurpose existing infrastructure creates a significant opportunity for more sustainable building practices in our changing climate. One advanced retrofitting technique is the use of externally bonded fibre-reinforced polymer (FRP) sheets, which has proven to be an effective method to increase the capacity of existing concrete, steel and masonry structures, and well-established techniques to design FRP retrofits have been incorporated into modern design codes (e.g. ACI 440 or CSA S806). However, research pertaining to the use of FRP sheets to retrofit timber structures remains limited, and as such, guidelines for the use of FRP to retrofit timber structures have not been incorporated into modern design codes. The aim of this research is to gain insight into the ability of externally bonded FRP sheets to increase the flexural capacity of glued-laminated (glulam) timber beams. A series of experiments are carried out on flexurally dominant glulam beams tested in four-point bending. Design approaches for different failure modes of potential retrofits with increasing layers of flexural FRP are assessed and an appropriate retrofit is chosen. Results of the study demonstrated that the FRP retrofitted specimen had an increase in flexural strength of 47.5% when compared to the control. Furthermore, the retrofit successfully changed the failure mode from a brittle tension failure to a ductile compression failure.

The use of post-tensioning in construction has revolutionized the construction industry and made way for a number of construction and structural applications that were unattainable before. One of the most important topics that is synonymous with the use of post-tensioning is the matter of accurately calculating the losses that arise in pre-stress, more specifically the short-term losses and long-term losses. One of the more prominent types of losses is the friction losses that occur during the jacking of the concrete elements. In this paper, the matter of friction losses in pre-stress will be explored by utilizing an on-site experimental investigation on real scale 30-m-span bridge girders. This provides great accuracy and reliability in the obtained results as the need to perform scaled modeling is eliminated. The research at hand incorporates an experimental setup in order to utilize strain gauges along the tendon length embedded in a concrete girder in order to accurately measure and map out the loss of strain that occurs in the tendons as compared to the tendons length, along with the pilot laboratory testing that were conducted in the labs before the site experimentations with the aim of perfecting the experimental setup. In total, 7 girders were tested on site in order to obtain the readings that will be used in the statistical analysis and findings of the research project. The behavior perceived in a large proportion of the tested girders is consistent with the expected behavior in the theory and literature with regard to the strain gain and strain loss throughout the different stages of girders jacking. Additionally, the perceived behavior shows that there is a shift in the values of the strain between different stations of the same tendons, meaning that the value of the strain measured decreases the further we move from the jacking end.

Damage assessment of infrastructure is a valuable tool for identifying severe distress and needs relating to repair and replacement. Although significant progress has been made towards the assessment of existing structures, predicting the structural response of reinforced concrete components under different stress conditions remains a difficult task. This paper focuses on the implementation of visually observed concrete crack data (i.e. crack widths and orientations) to estimate the structural response of cracked reinforced concrete elements. A smeared crack continuum model, namely the disturbed stress field model, is used as the foundation of the proposed crack-informed modelling procedure. Well-documented experimental crack data from reinforced concrete panel element tests in the literature have been used to evaluate suitability of the proposed modelling procedure for crack-informed structural assessment applications. It was observed that the proposed modelling approach was able to capture the key responses of the specimens in most cases. A mean absolute error of 13.7% was obtained for the relative residual strength of all specimens used for validation purposes.

The main goal of current design codes is to ensure the safety of people inside buildings during severe earthquakes. However, this objective must be achieved without excessive initial construction costs, and there is also a growing awareness within the earthquake engineering community of the importance of repair costs following a damaging earthquake. While the objective of different codes is reasonably consistent, various approaches are pursued to achieve this intent. The design of footings is a striking example of diversity in approaches. While the US code allows engineers to design for the reduced seismic design load, the Canadian code promotes designing footings based on the expected capacity of the seismic force-resisting system (SFRS). This discrepancy in codes can result in significant differences in footing size, potentially affecting the building performance. Hence, examining the repair cost of low-rise buildings could offer valuable insight into how the footing size impacts the seismic performance of these structures. In this study, a two-story building located on a class D site in Vancouver, Canada, is evaluated to assess the effects of the footing size on the expected seismic repair cost. This office building has an X-bracing system as the SFRS in the studied direction. Advanced numerical models are employed in OpenSees to simulate the building. The building repair costs are compared at the design ground motion intensity level, with reference to the relative significance of losses due to collapse, demolition, structural, and nonstructural losses. The results of this study suggest that for low-rise CBF buildings on soft soil, the best balance between initial costs and expected seismic losses appears to be near the size of a not capacity-protected (NCP) footing.

Past studies have shown that climate change can result in a nonstationary future climate. The nonstationarity of extreme climates poses challenges to the design community. It challenges the conventional assumption of using stationary historical climates to determine design loads in future design working life of infrastructure. Climate change adaptation to a changing climate requires consideration of the nonstationarity of the future climate in determining design values. Incorporation of nonstationarity of future climate into codes and standards is an effective way of adapting to a changing climate. To explore a practical approach, this paper will review and summarize examples of how the nonstationary future climate could impact structural design and reliability. Future projections for several regions in Canada will be used to explore the nonstationarity in a changing climate. The uncertainties of the nonstationarity in future predictions are discussed. The effect of how the nonstationarity is modeled on the design loads and reliability will be explored. The cost and benefit of having the nonstationary climate in the structure design are explored. Different combinations of climatic loads that could be affected by climate change are considered. Challenges and opportunities for incorporating the nonstationary climate into codes and standards are discussed.

Structural reinforcement with FRP sheets is increasingly being used for strengthening reinforced concrete structures, such as beams, slabs, columns, and piers. However, there are few data about the long-term durability of structural elements exposed to real climatic and environmental conditions. The authors carried out 10–15 year exposure tests on a variety of specimens that included concrete blocks with FRP plates bonded on one side. The specimens were located outside and submitted to the conditions of the Université de Sherbrooke campus. The paper presents an overview of these tests.

Electrical transmission tower-line systems form the backbone of our modern society, facilitating the seamless distribution of power over vast distances. The failure of any transmission tower among the line system can result in regional disruptions to power supply. Thunderstorm wind events pose significant threats to the structural integrity of transmission towers, making their fragility analysis crucial for ensuring the reliability and resilience of the power distribution systems. Deriving the fragility curve of transmission towers involves assessing the evolution of the joint probability density function of their responses. The structural response of these towers during the thunderstorm wind event always exhibits nonlinear characteristics; therefore, the nonlinear time-history analysis by using the finite element analysis is always adopted. However, conducting the time-history analysis for such scenarios is notably time-consuming, especially when combine the Monte Carlo simulation techniques and time-history analysis for fragility analysis. In the present study, an efficient procedure for the fragility analysis of the transmission tower subjected to bidirectional thunderstorm wind is described. The modeling of the wind field involves decomposing the thunderstorm wind into a time-varying mean wind velocity and a residual nonstationary fluctuation. The time-varying mean wind velocity is extracted from recorded thunderstorm wind data, and the variation along height is assumed to be proportional to the derived time-varying mean wind velocity. The nonstationary fluctuation is modeled as spatiotemporally varying by considering the incoherent effect and simulated using spectral representation method. For the modeling of the transmission tower, the uncertainty involved in yield strength and elastic modulus is considered. The proposed procedure incorporates a probability concentration-based simulation, combining aspects of the point estimate method and Latin hypercube sampling. Additionally, it employs a weighted (kernel) smoothing technique using simulated samples to estimate the evolution of joint probability density functions for tower responses. Finally, the time-dependent distribution of the transmission tower‘s top displacement subjected to thunderstorm wind is presented, demonstrating the effectiveness of the proposed procedure in assessing and understanding the vulnerability of these vital structures to such wind events.

Evaluations and rehabilitations of existing bridges are becoming more frequent given the increase in aging infrastructure across North America. Although numerous design strategies have been proposed to reduce the probability of progressive collapse of in-service bridges, the Canadian Highway Bridge Design Code (CSA S6:19) does not prescribe quantitative procedures or measures to assess the structural robustness of bridges. Robustness-based evaluations are therefore needed to help optimize resources for assessing and repairing the significant number of existing bridges across Canada. To address this research gap, a new structural robustness index is presented along with a separate index for structural redundancy. Both indices are bounded between zero and one and consider the structural response holistically by accounting for the performance of all elements in a quantifiable manner. A user-friendly framework of analysis is presented for both indices to facilitate application in engineering practice. The framework of analysis is first demonstrated on a simple two-dimensional truss structure subjected to lateral load, and the results are compared with five existing robustness measures published elsewhere. Lastly, to showcase the utility of the indices through practical application, the framework of analysis is utilized on an existing truss bridge in Nova Scotia subjected to various levels of corrosion.

Risk matrices are often utilized by owners to make informed decisions regarding the need and urgency of repair. A typical format of a risk matrix consists of defining the likelihood of occurrence of event (failure to meet the defined limit state in the case of structural evaluation) and the associated consequence. Existing practice of using risk matrices for decision-making indicates the qualitative assignment of the likelihood category based on a conventional member utilization design check. A simplified reliability-based approach to quantify the likelihood category to provide a direct correlation between reliability-based structural evaluation of existing structures and the decision-making process was developed and utilized by the authors. Features of the developed approach are highlighted in this paper. Variants of reliability-based risk matrices were applied in several real-life consulting works to evaluate the safety of existing structures in Canada. Three relevant case studies are outlined in this paper.

Over the past few decades, there has been a growing interest in the use of carbon fibre-reinforced polymers (CFRP) for the cables of cable-stayed bridges due to their high strength, corrosion resistance, relatively high stiffness, good fatigue resistance, and high resistance to creep rupture. One notable difference between the mechanical properties of steel and CFRP is their coefficients of thermal expansion at 12 × 10^–6 °C⁻¹ and 0.6 × 10^–6 °C⁻¹, respectively, and it is conceivable that this difference causes bridges with CFRP cables to behave differently under temperature loads than bridges with steel cables. A literature review revealed that very few studies examine this topic. This paper studies the structural performance of cable-stayed bridges with CFRP cables subjected to temperature loads by creating finite element models of a cable-stayed bridge with a main span of 250 m, one with steel cables and one with CFRP cables, and comparing their performance. The two bridges were subjected to thermal expansion and contraction loads, which were determined using the requirements of CSA S6-19. This paper collects and discusses the following data: cable forces; axial force, shear, and bending moment in the deck; axial force, shear, and bending moment in the pylons; and vertical deck displacements. It was found that temperature loads significantly impact the behaviour of bridges with CFRP cables due to CFRP’s low coefficient of thermal expansion, and it is evident that this behaviour is also affected by the type of connection between the deck and the pylons.

Unreinforced masonry (URM) buildings constitute the majority of existing buildings in Canada, including residential, governmental, and heritage structures. Most of these were built before the application of contemporary building guidelines and design codes, which suggests that many existing URM buildings do not necessarily have adequate seismic resistance, even in low-intensity earthquakes. Considering the progressive material deterioration over many decades and lack of maintenance frequently seen in old buildings, seismic retrofitting is necessary for continued occupancy of many structures. Moreover, the existing URM buildings were not originally designed to meet today’s energy performance criterion, which makes them less energy efficient and poses a heavy economic burden on homeowners and tenants who often have limited financial resources. To this end, a new multi-component research project has been launched to develop and test low-cost strategies for retrofit based on engineered timber. These systems are meant to enhance both the structural and thermal performance of ageing URM buildings in order to extend their working life. The strategy studied here comprises a structural layer made of plywood panels with cross-brace frames anchored to URM walls, as well as an energy layer comprised of bio-based thermal insulation. In this paper, preliminary results from ongoing full-scale structural and thermal experimental testing are presented alongside numerical modelling simulations that have guided the proposed design.

This study focused on the effect of jacketing (wrapping) damaged shear-deficient reinforced lightweight self-consolidating concrete (LWSCC) beam using U-shaped engineered cementitious composite (ECC) as a jacket to restore the shear strength and moment capacity of a beam. ECC is a category of ductile cement-based composite reinforced with polyvinyl alcohol fibers which exhibits features such as strain hardening, ability to develop multiple cracks, and self-consolidating making them useful for repair works. The shear-deficient core and ECC jacketed beams having constant aspect ratio (shear span to depth, a/d ratio) and longitudinal reinforcement (steel) were loaded to failure under monotonic loading. The load–deflection responses, ultimate load capacities, concrete cracking, steel strain development, and failure modes of the repaired jacketed beam were analyzed and compared with those of core LWSCC beam. The test result for the jacketed beam revealed a considerable increase in load-carrying capacity by 290% and increase in deformation capacity by 58% compared to the original core beams, the energy absorption increased by 684%, there was improvement in ductility index by 23%, and stiffness of the jacketed beam was 2.6 time higher than the core beam. The failure mode changed from shear to flexure when the damaged core beam was jacketed. Hence, a U-shaped ECC jacket can be used to restore the capacity of damaged LWSCC beams.

Long-span suspension bridges are prone to vibrations induced by multiple excitations, such as wind and seismic loads. This study introduces a novel strategy, damped outrigger, to enhance rotational damping of multiple modes and mitigate bridge vibrations. To verify the effectiveness of the strategy, a long-span suspension bridge with the main span of 1650 m is adopted as a case study. First, a reduced-order model of the bridge is employed to calculate the damping ratios of modes subjected to vortex-induced vibrations by modal analysis. Moreover, the variation in amplitudes of the main girder is examined under wind and seismic loads, respectively, to assess the efficiency of damped outriggers. The results show that with damping coefficients optimization aiming at the target modes, 6 out of 7 modes can attach additional damping ratio exceed 1.0%, and the corresponding amplitudes will reduce over 65% under vortex-induced forces. In addition, the seismic amplitudes could also be partly suppressed with damped outriggers. With further parameter optimization, it is anticipated that dual control of wind and seismic loads can be concurrently achieved.

Spherical concrete domes are commonly used in administrative buildings, silos, tanks, and subterranean structures. The main benefit of using concrete domes is utilizing both concrete durability and the high load capacity of a dome system that resists loads through meridian and ring stresses. The incident of an interior fire accompanied by superimposed loads requires specific considerations due to thermal deformations and material degradation resulting from the development of non-uniform temperature through the dome thickness. Moreover, dealing with ventilation-controlled fire, rather than standard fire, requires particular fuel load distribution and compartment ventilation considerations. This paper investigates the thermal behaviour assuming a ventilation-controlled steady-state temperature distribution within the dome space and transient temperature distribution through dome thickness while considering parameters related to ventilation factors and dome configuration. Outputs of the thermal analysis were fed into a structural model to estimate deformations and stresses. The effect of structural load ratio in conjunction with the ventilation factor during the fire incident was considered for a realistic study case.