Proceedings of the Canadian Society for Civil Engineering Annual Conference 2024, Volume 14

Table of Contents

1. Comparison Between Simulated Downburst Loads at the WindEEE Dome and Design Wind Loads for End Towers

   A. Ahmed, A. A. El Damatty

   Abstract

   Transmission lines (TL) are the arteries of the power infrastructure, responsible of delivering electricity over long distances. Extreme wind events have shown the vulnerability of transmission lines to wind loads through several tower failure incidents consistently happening around the globe. End towers serve as containment failure elements to stop the progression of failure of tangent towers. Downbursts are one of the windstorm phenomena that has led to many failures of TLs. The objective of this study is to assess through an aero-elastic test the adequacy of using the design loads for synoptic wind to design end towers to resist downbursts. The wind test is conducted at the Wind Engineering, Energy and Environment (WindEEE) Dome, which is capable of simulating downbursts. The downburst wind field and the shear forces at the base of the end tower are obtained from the test. Finite element analysis of the tested line is then carried out under both the downburst wind field measured experimentally and the synoptic wind load cases described in the ASCE guidelines. The straining actions produced by the downburst wind field measured in the test and the synoptic load cases are compared.

2. Effect of Foundation Flexibility on the Loads Acting on Offshore Wind Turbines

   M. Reda, A. Elansary, A. A. El Damatty

   Abstract

   Several studies have emphasized the importance of modeling the foundation flexibility of fixed-base offshore wind turbines (OWT). Including the soil–structure interaction (SSI) would give a softer model which reduces the natural frequencies of the turbine and makes them closer to the frequencies of the external loads which may lead to resonance. For the dynamic analysis of OWT, a simplified way is often adopted which simplifies or ignores the rotor nacelle assembly (RNA), SSI, ocean environmental loads, and operational conditions. Considering these, an integrated finite element model (FEM) ABAQUS is developed for monopile OWT including RNA, tower, monopile, and surrounding soil. The reference turbine used in this paper is the National Renewable Energy Laboratory (NREL) 5-MW wind turbine under stochastic ocean environmental loads. The dynamic response by ABAQUS model is compared to the response by the aero-hydro-servo-elastic simulation tool FAST. Default modeling of the foundation in FAST is a rigid connection between the substructure and the seabed, meaning that soil stiffness and damping are disregarded. Two different foundation modeling methods in FAST are investigated in this paper to determine the wind load response of wind turbines, the simplified apparent fixity method, and the improved apparent fixity method. Both methods represent the stiffness of the foundation system by adding one or two fictive beams below the mudline respectively. Finally, sensitivity analysis of wind wave correlation, wind wave misalignment angle, and operation and parked condition are conducted. It was concluded that ignoring foundation fixability leads to underpredictions of the structural dynamic response of offshore wind turbines.

3. Advancing Performance-Based Wind Design: Bridging the Gap Between Seismic Insights and Novel Strategies for Tall Building Resilience

   A. Ballate Delgado, A. A. El Damatty, P. Martín Rodríguez

   Abstract

   Performance-based wind design (PBWD) is an evolving research area aiming for a unified methodology for designing structures with predictable behavior. This field draws insights from performance-based seismic engineering, recognizing distinct challenges in applying these principles to wind engineering. Various studies propose deterministic and probabilistic approaches for wind hazard analysis and performance-based design methodologies. These studies explore modeling uncertainties in the performance evaluation process, often extending concepts from seismic design to wind scenarios. Two crucial factors are the number of inelastic cycles induced by wind and the consequential degradation of strength and stiffness. Analyzing the inelastic structural response in the time domain is essential, offering an understanding of energy absorption and force redistribution. The integration of experimental studies with numerical analyses is imperative for comprehending the particulars of performance-based design in wind engineering and navigating the boundaries of nonlinear analyses. This work aims to study the integration of seismic design concepts with the wind effect through a literature review of the methodologies proposed so far for performance-based wind engineering. The framework proposed by Elezaby and El Damatty with a coupled wind/seismic notion is presented to discuss the ductility-based approach for wind loads and future work considering different types of analysis. The first step of the methodology, which includes the evaluation and de-composition of elastic straining actions based on wind tunnel testing and finite element modeling, is analyzed using the case of study an irregular 19-story reinforced concrete building previously tested at The University of Western Ontario’s Boundary Layer Wind Tunnel Laboratory.

4. Developing a Finite Element 3D Model of the Composite Beams with PCHC Slabs Based on Full-Scale Pushout Tests

   Parinaz Panjehbashi Aghdam, Serge Parent, David W. Dinehart, Nathalie Roy

   Abstract

   Harsh climate conditions, as experienced in Canada, have raised a growing interest in precast construction. Precast concrete hollow core (PCHC) slabs featuring circular or ellipsoidal voids in their sections are structural elements that are precast and transported to the construction sites. Widely employed in multistory long-span structures, these slabs offer advantages such as being lightweight, cost-effective, easy to install, fire-resistant, and possessing superior thermal insulation. Despite their widespread application, current design codes overlook the significant aspect of composite action between steel beams and PCHC slabs. It is advantageous to consider this composite action in the design process, potentially leading to the specification of smaller steel beam sections. Shear studs play a crucial role in facilitating the establishment of composite action, underlining the need for a thorough investigation into their mechanical properties. This study aims to develop a 3D finite element (FE) model based on six full-scale pushout tests. These tests, conducted on full-scale composite beams with 254 mm depth PCHC slabs connected to steel beams via 19 mm diameter shear connectors, serve as the basis for quantifying the composite behavior. The FE model results are accurately calibrated against the experimental findings. Finally, a parametric study investigates the impact of the shear stud diameter and compressive strength of the concrete on shear stud capacity. Finally, the results of this study will provide valuable insights into the composite behavior of the steel beams with PCHC slabs.

5. CFD Prediction of Wind Pressures on Conical Tanks Based on a Wind Tunnel Test

   Engy Abdelhadi, Ashraf El-Damatty, Ahmed Musa, Ahmed Elansary

   Abstract

   Water tower vessels, often in the form of truncated conical tanks, are prevalent worldwide. These structures are typically constructed from steel, with curved panels welded together both circumferentially and longitudinally to achieve the conical shape. The meridional and hoop stresses resulting from the loads sustained by those tanks often lead to buckling of the tank’s walls and/or base, resulting in catastrophic failures. While the stability of conical tanks under hydrostatic and seismic loads has been extensively investigated in a comprehensive research program led by the second author and their team, the impact of wind loads remains inadequately explored. This chapter presents a comparative study aimed at predicting wind pressure on a conical tank using computational fluid dynamics (CFD) analysis conducted with ANSYS software, supplemented by the pointwise meshing tool and experimental wind tunnel tests. The study seeks to verify the accuracy of CFD simulations in predicting wind-induced pressures on the surface of conical tanks under wind conditions. A detailed description of the CFD simulation setup, including geometry modeling, mesh generation, boundary conditions, and turbulence modeling, is provided. The findings of the CFD simulations are compared with the available experimental data to evaluate the reliability and precision of the CFD approach in predicting wind pressure on conical tanks.

6. Mapping Seismic Hazard and Structural Reliability for Canadian Sites Considering Spatially Smoothed Seismicity Model

   C. Feng, H. P. Hong

   Abstract

   The estimated seismic hazard based on the delineated seismic source model is used as the basis to assign the seismic design loads in Canadian design codes such as in the National Building Code of Canada and the Canadian Highway Bridge Design Code. An alternative approach to estimate and map the seismic hazard is to use the seismicity model obtained based on the historical earthquake catalogue and spatial smoothing techniques. However, quantification of differences in the Canadian seismic hazard maps (CanSHMs) obtained based on the delineated seismic source model and smoothed seismic source model is unavailable. The quantification is valuable to identify epistemic uncertainty in the estimated seismic hazard and the degree of uncertainty in the mapped CanSHMs. In the present study, we develop seismic source models based on spatial smoothing and historical earthquake catalogue. We carry out systematic quantification of the differences in the estimated and mapped Canadian seismic hazard by considering the delineated source model and spatially smoothed source models. For the development of the spatially smoothed seismic source models, we consider both spatial kernel smoothing techniques with or without adaptive bandwidth. The results indicate that the use of the delineated seismic source model could lead to under or over-estimation of the seismic hazard as compared to those estimated based on spatially smoothed seismic source models. This suggests that an epistemic uncertainty caused by the seismic source model should be considered to estimate and map the seismic hazard, which can be done by expanding the logic tree that includes multiple seismic source models to evaluate the seismic hazard. Furthermore, the implication of using one or the other approach in mapping seismic hazard on structural reliability is investigated by using an equivalent nonlinear inelastic single-degree-of-freedom system.

7. Estimating Extreme Peak Wind Pressure Coefficients on Low-Rise Buildings Subject to Thunderstorm Winds

   Y. X. Liu, H. P. Hong

   Abstract

   Thunderstorm winds are characterized by significant low-frequency components or time-varying mean wind speed. In addition, the mean wind direction is time dependent. These are unlike the stationary synoptic winds which are commonly modeled with time-invariant mean wind speed and direction. We quantify the effects of the time-varying mean wind speed and direction, and the nonstationary fluctuating components of thunderstorm winds on the extreme peak wind pressure coefficient for a low building. For the quantification, we propose a simulation-based procedure and apply the equivalent-steady-gust model and the quasi-steady-vector model. The effect of the random orientation between the structural principal axis and the wind direction corresponding to the maximum mean wind speed (i.e., directionality effect) on the extreme peak wind pressure coefficient is also considered. By using the already available pressure coefficient obtained from the boundary layer wind tunnel tests, numerical analysis is carried out by considering the thunderstorm winds in the horizontal plane.

8. A Study on Peak Pressure Estimation for High-Rise Buildings Without Extended Wind Tunnel Duration

   Latife Atar, Oya Mercan

   Abstract

   The determination of design wind pressures for component and cladding loads is a crucial aspect of building design. In the case of high-rise buildings, these pressures are often assessed through wind tunnel tests. While several methods exist to estimate peak pressures, the Gumbel distribution, and the generalized least square method, also known as the BLUE method, are commonly employed for estimating peak pressure data. The wind tunnel test duration and the number of peaks considered in the estimation are key parameters in this process. While guidelines for low-rise building peak pressure estimation are commonly followed in the case of high-rise buildings, it is essential to acknowledge the unique challenges posed by the latter. High-rise buildings typically involve smaller model scales compared to low-rise buildings, necessitating special considerations in peak pressure investigation. For reliable statistical analysis, recent studies have proposed the use of extended duration to estimate one-hour statistics more accurately for reliable peak pressure coefficients. The objective of this study is to investigate how varying the number of peaks utilized in peak estimation impacts the estimated peak pressures for data with both highly and mildly non-Gaussian characteristics, specifically focusing on one-hour length datasets. Additionally, the study aims to explore the non-Gaussian features of high-rise buildings across different building heights.

9. ModularBuildingPy: A Python-Based Numerical Modeling and Analysis Tool for Volumetric Modular Steel Buildings

   Mehmet Baris Batukan, Oya Mercan

   Abstract

   Modular steel buildings (MSBs), which are constructed using prefabricated volumetric modules, are increasingly acknowledged as an alternative solution to meet immediate housing needs. These modules are manufactured offsite and then assembled onsite to create multi-story structures. Modular structures inherently possess complex characteristics in their 3D numerical models such as separate diaphragms for each unit and vertical and horizontal connections between the units. Therefore, the development of a Python-based tool, ModularBuildingPy, is an important step in managing these inherent model complexities. It not only minimizes potential modeling errors through automation of the connection details and consistent application of modeling rules, but also accelerates the creation of numerical models, generating them quickly. Moreover, through integration with OpenSeesPy, the tool can effectively perform structural analysis and obtain the structural response (e.g., base shear and inter-story drift values). This provides valuable insights into the structural behavior of the MSBs under various loading conditions such as gravity and seismic. The simulation results can guide design decisions, contributing to the overall safety and serviceability of these structures. To demonstrate the effectiveness and versatility of the Python-based tool, two case studies were conducted focusing on both low- and high-rise MSBs. These case studies provide practical examples of how the tool can be used to generate numerical models quickly and accurately, and to extract results from the analyses. The results from these case studies emphasize the tool’s potential in facilitating the modeling and analysis of MSBs of varying dimensions and complexities.

10. Visualization of Surface Pressure and Flow Field Dynamics Induced by Vortex Shedding Around Tall Buildings

    Zian Cheng, Jack K. Wong, Oya Mercan, Keith Feranades, Ziyi Wang

    Abstract

    Vortex shedding topology and its influence on the pressure dynamics for large aspect ratio buildings under the atmospheric boundary layer inflow conditions are studied. A numerical study using large eddy simulation (LES) is conducted on two rectangular high-rise buildings with different blockage ratios with divergence-free turbulence generator. Two flow visualization techniques, namely phase averaging and dynamic mode decomposition (DMD), are employed to extract the spatial patterns of the velocity field and the pressure field around the vortex shedding frequency. For the phase-averaging technique, the importance of applying a reliable vortex shedding frequency detection algorithm is discussed in detail and the result is compared with the fixed-frequency-method. Phase-averaged velocity and pressure contours based on the stationary and convective reference frame are presented and analyzed as part of the investigation. For the DMD technique, a parametric study is performed on the number of snapshots and delay embedding length. The two techniques result in similar patterns. By establishing this visualization, the study assists in comprehending the dynamics of the flow field and its alterations in response to changes in building geometry. Additionally, it sheds light on how these dynamics impact the surface pressure on each wall.

11. A Simplified Thermo-mechanical Model for Damage Assessment in Concrete Gravity Dams Due to Alkali-Aggregate Reaction (AAR)

    Avirup Sarkar, Bikram Kesharee Patra, Ashutosh Bagchi

    Abstract

    Large dams, integral to global infrastructure, confront a critical challenge of aging as many surpass the 50-year mark, and some approach a century in service. With over 61,000 such structures worldwide, ensuring the safety of aging dams has become a global imperative. This deterioration is exacerbated by alkali-aggregate reaction (AAR), leading to weakening of concrete, cracking, and jeopardizing dam integrity. Alkali-aggregate reaction emerges as a primary cause of concrete gravity dam deterioration, prompting a comprehensive reassessment of safety using contemporary advancements. In the realm of modern structural engineering, the twenty-first century presents a distinctive challenge: employing advanced computational techniques to assess infrastructure safety against the forces of aging, shaking, and cracking. The second law of thermodynamics, coupled with unpredictable natural forces, demands a re-evaluation of dam safety. This paper delves into the critical issue of AAR in large concrete structures, with a specific focus on concrete gravity dams. The process of aging and the resulting risk of AAR-induced cracking pose a significant threat, compelling dam owners to implement preventive measures. The study introduces a simplified modeling approach based on thermo-mechanical analysis, employing finite element method (FEM) in the time domain. This approach is validated against conventional AAR models, demonstrating its effectiveness in predicting strains and stresses induced by AAR effects. The proposed modeling technique provides a unique way to estimate the mechanical damage to concrete gravity dams due to AAR, and also the computational efficiency of the time domain-based finite element method (TDSFEM) over traditional FEM. This computational advantage is particularly crucial for analyzing large structures like concrete gravity dams, marking a significant stride in ensuring the sustained safe utilization of these critical infrastructures.

12. Decarbonization Strategies for the Structural Design of Reinforced Concrete Buildings

    Ahmed Noman, Ashutosh Bagchi, Andreas Athienitis

    Abstract

    Building construction has a significant impact on embodied energy and greenhouse gas emission. These factors are associated with the production, transportation, building construction, demolition, disposal, and recycling of materials. The reduction of embodied energy and greenhouse gas emission is related to reduction in carbon imprint, which is often referred to as decarbonization. By adopting an appropriate structural design strategy for reinforced concrete buildings, it is possible to reduce the seemingly contrasting factors such cost of materials and construction, but also the embodied energy and carbon footprint. Because of the excellent reuse and recycling potential and relatively very high mechanical strength of steel, a structural component with a higher steel apportionment than that required for a cost-optimized solution commonly results in lower embodied energy and CO₂ emission conducive to sustainability and decarbonization. In this study, a detailed parametric study has been conducted for reinforced concrete buildings with different design alternatives for building structures to achieve minimal cost, embodied energy, and CO₂ emission. A set of 5-, 10-, and 15-storey high buildings located in Montreal, Canada, have been considered. Flat plates and flat slabs with drop panels supported by columns are quite common for multi-story buildings in North America. Therefore, these forms of the building structure have been considered. Among many different parameters, column steel ratio and slab thickness play an important role in cost, embodied energy, and carbon footprint. The foundation also accounts for a sizable portion of total structural cost, material, and embodied energy. Two types of raft foundation have been considered here for multi-story buildings: flat-plate rafts and beam-slab rafts, as they are quite common. Compared with flat-plate building foundations, flat slabs buildings foundations have been found to be favorable for cost, embodied energy, and carbon emission. Also, beam-slab rafts are found to perform better on these counts.

13. Study on the Performance of Structures Located Above Underground Metro Tunnel

    Sathiya Narayanan Sankar, Amal Pradeep, Ashutosh Bagchi

    Abstract

    In many developed countries, underground metros are a common mode of transport to reduce traffic congestion on the roads. Based on the soil profile and type, the depth of the underground metro tunnel varies with location. Construction and operation of a metro tunnel could induce vibration that could affect the performance of structures above the tunnel, within its influence zone. The influence zone is termed as the zone that may experience higher to lower vibration due to construction or train movement. The metro station’s constructions are crucial in densely populated areas, as the construction process is carried out by erecting shoring piles along the station’s perimeter and tunneling by TBM machines (Tunnel-boring machines). As the TBM rotates with much intensity during construction, the soil may experience a shock and differential settlement due to the soil’s behavior. The structure above the tunnel may experience vibration and deformation. Moreover, even after construction, vibrations will be experienced in many structures due to train movement. The tunnel diameter is around 7–10 m according to the need of train activity. The soil-structure interaction plays a vital role, during the vibration of soil surface due to train movement. Major failures such as settlement of the structure, failure of beam-column joint, and reduction in durability of the building may occur due to continuous underground train movement. This paper aims to assess the structural response of residential buildings situated above underground metro tunnels to dynamic train-induced vibrations, with a focus on understanding the potential risks to structural integrity and occupant comfort.

14. Influence of Bond Length on the Fatigue Repair of Cracked Steel Plates Using Ultra-high Modulus CFRP

    Gavin Li, Amir Fam, Joshua Woods, Brahim Benmokrane

    Abstract

    This study evaluates the effectiveness of externally bonded ultra-high modulus (UHM) carbon fibre-reinforced polymer (CFRP) plates in the fatigue life extension of steel plates with simulated fatigue cracks using different lengths of CFRP. The study investigates bond lengths approximately 1.0 and 2.5 times the effective development length of the CFRP-steel system. Digital image correlation (DIC) and beach marking techniques were used to track fatigue crack propagation. This study found that a maximum fatigue life extension ratio (FLER) of 2.53 was observed in a steel plate with 25% initial cross-sectional area loss and retrofitted with a 300 mm long UHM CFRP plate (i.e. a bond length of 150 mm) applied to a single side of the plate.

15. Cast-In Connection Strength in Very Thin Ultra-high-performance (UHPC) Wall Panels

    Hoda Osman, Amir Fam

    Abstract

    A new generation of double wythe insulated sandwich wall panels is being developed at Queen’s University for the precast industry through the Canadian Precast/Prestressed Concrete Institute (CPCI). The new design uses very thin ultra-high-performance fiber-reinforced concrete (UHPFRC) wythes of 15–38 mm, which enables a remarkable reduction in self-weight and savings in transportation and craning operations. However, the challenge with thin walls is securing enough embedment for connections. This study investigates the pull-out strength of a variety of connection configurations and varies the wythe thickness, polymeric fiber ratio in the mix, connector diameter, embedment depth, back cover, and end bearing area. It was concluded that current equations overestimated the capacity of cast-in connectors in thin UHPFRC panels. As a result, a multiple linear regression analysis is carried out to develop design expressions for these connections.

16. A Reevaluation of CSA S304-14 Geometric Requirements for Concrete Masonry Prisms

    Will Pahl, Ting Hin Chui, Lisa R. Feldman

    Abstract

    The geometry of masonry prisms is governed by Annex D of CSA S304-14—Design of Masonry Structures and ASTM C1314-18—Test Method for the Compressive Strength of Masonry in Canada and the United States, respectively. CSA S304-14 requires prisms to be one-block wide and at least three courses tall if grouted, while ASTM C1314-18 allows prisms that are one-half block wide and two courses tall. The larger prism size as used in Canada is hindering their use on jobsites given their excessive weight and cost and limits the number of laboratories capable of testing these prisms to failure. The scarcity of prisms on Canadian jobsites is problematic as reports of understrength constituent materials or other construction-related problems may arise with no means of otherwise confirming the adequacy of construction. An experimental program consisting of 196 prisms was therefore conducted at the University of Saskatchewan to evaluate the influence of prism width and height, bedding type, construction pattern (i.e., stack pattern or running bond), and presence of grout on the resulting compressive strength. Results indicate that prism strength is insensitive to width and so suggest that one-half block wide prisms would be reasonable for use in Canada. These smaller prisms would encourage their construction on jobsites to better allow for confirmation of as-constructed assemblage strength and member resistance.