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The structural steel design specification in Canada, CSA S16-14, uses the same equations for the design of rolled and welded shape beams for lateral torsional buckling (LTB). A recent study has shown that the current design equations might overestimate the capacity of welded wide flange (WWF) beams. This paper evaluates the performance of the current design equations in providing LTB capacities of welded I-shape beams (WWF beams). An extensive finite element (FE) analysis is performed for simply supported WWF beams subjected to constant moment. In total, 256 FE models are analyzed and it is observed that both CSA and AISC overestimate the LTB capacity of welded I-shape beams by as much as 37%, particularly when residual stress measured at Lehigh University is used in the analysis. Also, the Eurocode is found to be conservative and the proposed equation by MacPhedran and Grondin in 2011 provides better predictions of LTB strengths of WWF shapes than the current CSA approach. [ABSTRACT FROM AUTHOR]

Design specifications in North America, unlike their European counterpart, use same equations for design of rolled and welded shape beams for lateral torsional buckling (LTB). A recent study by MacPhedran and Grondin (2011) has shown that the current Canadian design equations might overestimate the capacity of welded wide flange (WWF) beams, which are welded I-shapes, requiring further investigation. This paper evaluates the performance of the current design equations for LTB capacities of welded I-shape beams. Nonlinear Finite Element (FE) analysis is performed for simply supported WWF beams subjected to constant moment, linear and nonlinear moment gradient. Three types of linear moment gradients are investigated: end moment ratios of 0.5, 0.0, and − 1.0. Also, two types of transverse loadings are considered: a concentrated load at mid-span and uniformly distributed load along the length, and applied at the top flange, shear center, and at the bottom flange. In total, 416 FE models are analyzed and it is observed that for constant moment loading both CSA and AISC overestimate the LTB capacity of welded I-shape beams by as much as 37%. FE analysis also shows that current CSA strength curve overestimates significantly the strength of WWF beams by as much as 40% for end moment ratio of 0.5. For transverse loading, current CSA strength curve overestimates the capacity significantly for top flange loading and underestimates for bottom flange loading. Also, Eurocode is found to be conservative for all cases and the proposed equation by MacPhedran and Grondin (2011) provides better predictions of LTB strengths of WWF shapes than the current CSA approach. [ABSTRACT FROM AUTHOR]

I-shape steel columns in many old bridges can be rehabilitated by welding steel plates to the flanges of the existing columns. However, the effect of welding residual stresses, initial imperfections, and column load at the time the reinforcing plates are welded to the column can significantly affect the column strength. Currently there are no guidelines available for the design of columns reinforced under load with welded cover plates. This paper presents a numerical study to determine the appropriate column curve, whether SSRC column curve 1 or 2, i.e. n = 2.24 or 1.34 in the Canadian steel design standard, to use for design of columns reinforced with steel cover plates welded to the flange tips, either parallel to the web or parallel to the flanges. A validated finite element model is used to conduct a parametric study to investigate several parameters that affect the strength of the reinforced column. Considering the variation in the resistance, a detailed statistical analysis, which provides a uniform level of safety, is conducted based on the results obtained from the parametric study to determine appropriate resistance factor to use for limit state design of columns reinforced with welded steel plates. A reliability analysis indicated that steel columns reinforced with plates welded under load should be designed using SSRC column curve 2 ( n = 1.34) with a resistance factor of 0.90. [ABSTRACT FROM AUTHOR]

Abstract: The behaviour of unstiffened steel plate shear walls with circular perforations in the infill plates is examined. A shear strength model of the infill plate with multiple circular openings is proposed based on a strip model. Eight perforation patterns in a single storey steel plate shear wall of two different aspect ratios were analyzed using a geometric and material non-linear finite element model to assess the proposed shear strength model. A comparison between the nonlinear pushover analysis and the proposed shear strength equation shows excellent agreement. The proposed model is used to design the boundary columns of three sample four-storey perforated shear walls. A comparison between the predicted design forces in the boundary columns for the selected shear walls with the forces obtained from nonlinear seismic analyses demonstrates the accuracy of the proposed simple model to predict the design forces in the columns. [Copyright &y& Elsevier]

Abstract: The behavior of unstiffened thin steel plate shear walls with circular perforations placed at the center of the infill plates is examined. A shear strength equation is developed for perforated steel plate shear wall with circular perforation at the center. A series of single storey perforated steel plate shear walls with different aspect ratios and different perforation diameters were analyzed to assess the proposed shear strength equation. A comparison between the nonlinear pushover analysis and the proposed equation shows excellent agreement. The proposed shear strength equation is applied for design of boundary columns of one 4-storey and one 6-storey perforated steel plate shear walls. The predicted design forces in the boundary columns for the selected perforated shear walls are compared to the forces obtained from nonlinear seismic analysis. The proposed equation gives very good predictions for the design forces in the boundary columns. [Copyright &y& Elsevier]

Multi-sided steel tubular sections are commonly used in many structures such as high mast lighting and sign supports. Current AASHTO standard for Structural Supports for Highway Signs, Luminaires, and Traffic Signals provides width-thickness limits to check for local buckling of octagonal (8-sides), dodecagonal (12-sides), and hexadecagonal (16-sides) steel tube sections when they are subjected to axial compression and bending. Although multi-sided tubes are used in many structures, very limited study has been conducted to evaluate the slenderness limits of these thin-walled sections. This paper presents a finite element (FE) analysis based study of local buckling of multi-sided steel tubular sections. A nonlinear FE model is developed for this study and validated against experimental results from stub column tests of 8-, 12-, and 16-sided cross-sections. The FE model is then used to analyze a series of multi-sided tubular sections subjected to axial compression or pure bending. Results from FE analyses are used to evaluate the slenderness limits specified in different standards (AASHTO, ASCE, and Eurocode 3). FE analyses show that AASHTO provided compact limit for many multi-sided tube sections are non-conservative when subjected to flexure and might need to be revised. Also, current non-compact section limits are quite relaxed for the sections subjected to pure bending. Based on FE results, revised compact and non-compact limits have been proposed for octagonal, dodecagonal, and hexadecagonal multi-sided tubular sections. Moreover, FE analyses indicate that the non-compact limit of the hexadecagonal section can also be used for the other two sections under axial compression. • FE based study conducted to evaluate slenderness limits specified in different standards for multi-sided tube sections. • Study shows AASHTO compact limit for many multi-sided tube sections are non-conservative when subjected to flexure. • Non-compact limit of the hexadecagonal section can be used for octagonal and dodecagonal multi-sided tube sections. • AASHTO and Eurocode 3 provide good predictions of the compressive resistance for multi-sided tube sections. [ABSTRACT FROM AUTHOR]

Abstract: Seismic design codes generally specify empirical formulae to estimate the fundamental vibration periods of buildings. Currently, most building codes provide the same empirical formula to estimate the fundamental periods for steel plate shear walls and reinforced concrete shear walls. The work presented in this paper shows that the code formula predicts periods that are generally shorter than the periods obtained from a validated finite element analysis of a series of steel plate shear walls of different geometries. An improved simple formula for estimating the fundamental period of steel plate shear walls is developed by regression analysis of the period data obtained from analysis. In addition, the effectiveness of a simple shear–flexure cantilever formulation for determining fundamental periods and effects of steel plate shear wall systems is presented. The effects of perforations in the infill plates and column base support conditions on fundamental periods are also explored. [Copyright &y& Elsevier]

This paper presents a capacity design procedure that aims to achieve good seismic performance for steel-plate shear walls and improve the overall economy of the system. The proposed method uses indirect capacity design principles to identify the infill plates most likely to yield in the design earthquake. Linear models of the boundary columns are used to determine the column design forces. The proposed method is used for the design of two 4-story and one 8-story steel-plate shear walls. Design axial forces and moments in the boundary columns for the three different steel-plate shear walls are compared with nonlinear seismic analysis results, and the results of the proposed procedure are shown to be in good agreement with those of the nonlinear analyses. For comparison, the paper also evaluates other capacity design approaches that have been proposed in the literature. [ABSTRACT FROM AUTHOR]

A finite element model is developed to study the behaviour of unstiffened steel plate walls. The model includes both material and geometric nonlinearities and strain rate effects. The model is first validated using the results from quasistatic and dynamic experimental programs. The validated finite element model is then used to study the performance of four storey and eight storey steel plate walls with moment-resisting beam-to-column connections under spectrum compatible seismic records for Vancouver and Montreal. Two different steel plate wall types defined in the current Canadian standard CAN/CSA-S16-01 are considered, namely, Type D (ductile) and Type LD (limited-ductility) plate walls. All the Type D walls, designed according to the capacity design provisions, exhibit better inelastic seismic responses than the Type LD plate walls. The analyses of eight storey steel plate walls show that in high seismic regions, such as Vancouver, medium- to high-rise Type LD plate walls may exhibit yielding in columns in intermediate floors. The study also shows that in more moderate seismic regions, like Montreal, Type LD plate walls behave in a stable and ductile manner and can be used for low- to medium-rise buildings. [ABSTRACT FROM AUTHOR]

Abstract: Nonlinear seismic responses of a typical 15-storey and 4-storey steel plate shear wall are studied. Dynamic shear and moment envelopes are compared with the current CAN/CSA-S16-01 seismic capacity design approach. It has been observed that estimated dynamic base shear forces and overturning moments in the steel plate shear walls, as well as the column forces, are underestimated in the current seismic design provisions. The effect of loading rate on the dynamic behaviour of steel plate shear walls is also investigated. Nonlinear dynamic analyses show that loading rate increases flexural demand mostly at the base of the steel plate shear wall and loading rate has a small effect on inelastic seismic demand for a suite of spectrum compatible earthquake records for Vancouver. Also investigated is the –delta effect on seismic demand in shear and flexure. The inelastic seismic analyses indicate that the current National Building Code of Canada stability factor approach to account for –delta effects is very conservative for steel plate shear walls and the –delta effects on seismic demand are very small. [Copyright &y& Elsevier]

Steel plate shear wall (SPSW) with regularly spaced circular perforations has recently been developed. While the current edition of AISC 341-16 and CSA S16-14 have adopted perforated SPSW (P-SPSW) in their design standards, no simple numerical model is currently available for analyzing this SPSW system. A reliable macro-model is developed for regularly spaced circular perforations. The proposed macro-model is validated against available experimental results. Performance of three multi-storey (4-, 7-, and 10-storey) perforated SPSWs designed according to CSA S16-14 and NBCC 2015 is further investigated through conducting a series of time history analyses using a suite of 44 ground motions developed for western Canada. When compared with seismic analysis results of solid SPSWs, it is observed that the median shear envelopes for P-SPSWs are slightly less than that for solid ones. Also, in comparison to solid SPSW archetypes, the contribution of boundary columns in resisting the storey shear is found higher than the infill plate in most of the stories in P-SPSW archetypes. Finally, a sensitivity assessment is performed to evaluate the effect of perforation diameter on different responses of P-SPSWs, such as peak column axial forces, peak column bending moments, and maximum interstorey drift. It is observed that with an increase in the hole diameter, column axial force demand decreases, while the bending moment remains almost the same. Also, since adding perforations to the infill plate reduces the stiffness and strength of the P-SPSW system, the interstorey drift ratio is increased in comparison to solid SPSW. • A strength deterioration model is developed for perforated steel plate shear wall • Seismic analyses of solid and perforated steel plate shear walls are conducted • Column axial force in perforated SPSW decreases with an increase in hole diameter • Columns of perforated SPSW resist more storey shear than the infill plate [ABSTRACT FROM AUTHOR]

• A new component strength deterioration model for stiffened infill plate. • Collapse performance of stiffened steel plate shear wall using FEMA P695 methodology. • Incremental dynamic analysis of stiffened steel plate shear walls. • Estimation of seismic response modification factors for stiffened steel plate shear wall. Unlike unstiffened steel plate shear walls (SPSWs), very little research has been conducted to assess the seismic performance of stiffened SPSWs. This paper presents a new component strength deterioration model for stiffened infill plate to evaluate the seismic performance of stiffened SPSWs using FEMA P695 procedure. The newly developed component strength deterioration model is first validated against the available experimental results. A total of three multi-storey (7-, 10-, and 13-storey) stiffened SPSWs with panel aspect ratio of 1.39 are then analysed using the proposed component strength deterioration model. Static pushover and incremental dynamic analyses using a suite of 44 ground motions compatible to Western Canada are conducted for all archetypes. Adjusted collapse margin ratios obtained for stiffened SPSWs designed with similar response parameters of those for unstiffened SPSWs are compared with allowable limits given in FEMA P695. The results indicate that currently recommended seismic response modification factor, ductility related force modification factor and overstrength related force modification factor, for unstiffened SPSW can be used for design of stiffened SPSW. In addition, seismic response parameters such as variation of maximum interstorey drift and shear demand in different components of stiffened SPSW, boundary columns and infill plates, are estimated in all stories for all designed archetypes during incremental dynamic analysis. Furthermore, seismic response sensitivity of stiffened SPSWs to the variation of post-yielding parameters (i.e., ductility capacity and post-cap stiffness ratio) in infill plate is investigated. Sensitivity analysis shows that the capacity of stiffened SPSW is more sensitive to ductility capacity changes, while the variation of post-cap stiffness has a lesser effect on overall performance of the system. [ABSTRACT FROM AUTHOR]

This paper presents a closed form solution for the analysis and design of composite steel concrete (SC) shear wall systems subjected to pure out-of-plane loads with partial interaction theory. This method takes into account the flexibility of connection between plate and concrete. SC walls under out-of-plane loads can be considered a slab under distributed loads; therefore, for obtaining the formulation of these systems, a strip beam-slab is considered. These walls are subjected to soil pressure when used in deep excavations water hydraulic pressure when used as marine structures, and ice moving pressure when used in offshore structures etc. For providing the interaction between steel and concrete, shear connectors and, for calculating the out-of-plane loadings, classic methods are utilized. The existence of concrete in composite shear walls not only prevents the steel plate from buckling, but also plays an important role in out-of-plane resistance. To investigate the effect of concrete on the behavior of these SC shear walls, two cases are considered in this study: shear walls with and without concrete. To validate the accuracy of the proposed method, a number of shear walls were modeled and analyzed by ABAQUS software and compared with the results from theoretical formulations. Results indicate that the proposed interaction theory is well capable of predicting the deformation and stress distribution of the composite shear walls. [ABSTRACT FROM AUTHOR]

• Review of state-of the-art methods for wind actions on canopies. • Focus on low-rise buildings. • Focus on all available wind tunnel studies. • Comparison between international codes. • Comparison between experimental results and code-prescribed values. Overhangs are commonly used in residential and industrial buildings for the convenience of residents and users. Canopies are very prone to wind loading due to the suction developing on their upper surface along with the pressure occurring on their lower surface (for most wind directions), which together may generate critical uplift forces causing serious damage. The paper presents past research on wind effects on canopies of low buildings, originated mainly from atmospheric boundary layer wind tunnel studies. Provisions for wind pressure on canopies in different wind standards and codes of practice are also reviewed. Findings of past and recent studies are then compared with the provisions of various National Codes on wind loading on canopies. Comparisons of the experimental results with some computational results and the provisions of wind codes and standards show significant discrepancies. Some of these differences are due to the variety of configurations used in the previous studies, e.g. building geometry, size and slope of overhangs, canopy location on the wall(s), existence of openings, as well as roof shape (flat, gabled or curved / arched). [ABSTRACT FROM AUTHOR]