Vertical Boundary Elements Research Articles

SEISMIC RESPONSE OF REINFORCED CONCRETE FRAMES WITH STEEL PLATE SHEAR WALLS

This study aimed to evaluate the effect of using steel plate shear walls (SPSWs) on the earthquake response of reinforced concrete (RC) moment resisting frames. For this, two types of RC frames, namely, ductile and nominally ductile RC frames were used. Each frame structure had five storeys and three-bays. The first storey height was 4 m while the height of the other storeys was 3 m. To upgrade the performance of the existing structures under seismic actions, a special unstiffened SPSW system was incorporated into the middle-bays of each frame. SPSWs consist of an infill steel plate, horizontal and vertical boundary elements such as beams (as HBEs) and columns (as VBEs). The structures were modeled analytically using a finite element method and evaluated by both nonlinear static (pushover) and time history analyses. In the pushover analysis, the first mode load distribution and uniform load distribution were used. In the dynamic time history analysis, a set of ground motion records was employed. As a seismic hazard level, 2% probability of exceedance in 50-year period was taken into consideration. The seismic response of the ductile and nominally ductile RC frames with and without SPSWs was examined comparatively. The results indicated a considerable enhancement in the earthquake performance of both the ductile and the nominally ductile RC frame structures with SPSWs.

Determination of Lateral Force on Steel Plate Shear Wall by using American Code

For seismic design requirements, the major stress dispersing components for steel plate shear walls (SPSWs) that be resistant against lateral forces are un-hardened plates infilled (webs) that bend for shear then shape the sequence with diagonal tension field actions (TFAs). The tensile load of an infill plate must be resisted through the horizontal boundary elements (HBEs) and the vertical boundary elements (VBEs) surrounding every plates by means with its capacity design point of view. If rigid connections were established for both the HBEs and the VBEs as well as among VBEs even its base (when stated with other SPSW cases), the SPSWs often gain along with moment of resistance from another boundary element with that of its lateral horizontal forces deployed. Appreciating every usefulness by their boundary frame with their overall strength in that model, through their interest as can also occur in any form of optimizing the design of the SPSW, so instead of based for their appearance to this process for the over strength with which this can supply for withstand a defined lateral forces. About the lateral design, many aspects control its reaction to light – frame shear wall: rank the encasing elements, fastener style, fastener position, keep on low tightening system, size as well as the classification with the connected structural boards, existence frame connections, aspect ratio in the wall (height of the wall and length of the wall ratio), with wall attached components. While framing products and fastener forms vary throughout Cold – Formed Steel (CFS) as well as wood – frame shear wall mechanisms, a whole responds for those mechanisms also seem to be relatively equal when they are sufficiently comprehensive to resolve the material centric limit states. The steel plate shear wall (SPSW) arrangement seems to be recognized just like most among any simplest efficient ways for resistance of the lateral forces, specifically through seismic activity, the loads are adapted on the model. This comprises along with one steel plate infilled attached through an enclosed system throughout horizontal beams and vertical columns for the movement of lateral forces to the base of the foundation. Steel plate shear walls (SPSWs) column in mid – rise along with high – rise constructions typically needs an outsized compression capability, because it bear either an axial forces with gravitational forces of lateral forces and imposed by the moment of overturning. In order to ensure the effective usage with steel inward the plate infilled, and even will attain goodness as a whole earthquake output on that wall, that formed tension field need to have relatively consistent, requiring suitable anchoring by effective accompanying members of the frame. The lateral fore on the steel plate shear wall (SPSW) is determined by using American code.

Seismic performance of concrete-infilled double steel corrugated-plate walls: Experimental research

The Concrete-infilled Double Steel Corrugated-plate Wall (CDSCW) consists of a corrugated part and two vertical boundary elements. The corrugated part is composed of two steel corrugated plates (SCPs) and infilled concrete, where high-strength bolts connect the two SCPs. The two vertical boundary elements are concrete filled steel tubulars. Obviously, owing to the corrugation configuration of SCPs as well as the positive interactive effect among SCPs, infilled concrete and vertical boundary elements, a CDSCW can attain high axial load-bearing efficiency and good seismic performance. This paper presents the experimental seismic performance of CDSCWs by exerting horizontal cyclic loads under constant axial compressions. Eight specimens were tested, with axial compression ratio, shear span to depth ratio and eccentricity of in-plane compressive load as the main research variables. The experimental results indicated all the specimens subjected to compression-bending failure with failure modes closely related to their axial compression ratios. There was a significant negative correlation between the axial compression ratio and the ductility of CDSCW specimens. In addition, the shear to span depth ratio had an important influence on the ductility of CDSCW specimens. Moreover, the experiment showed that the sectional axial strain distribution of CDSCW specimens conformed to the plane section assumption before reaching their peak load-bearing capacities, and most of the steel fibers except the ones near the neutral axis could be considered as plastic when the CDSCW specimens subjected to in-plane combined compression-bending-shear loads. Based on this, the formulae for estimating the load-bearing capacity of the CDSCW specimens under the combination of constant axial compressions and horizontal cyclic loads are established. The comparison between the formula values and the experimental results proves that the formulae are accurate and conservative. The conclusions of the experimental investigation provide fundamentals for the establishment of CDSCW seismic design method.

Effect of Outrigger Panels on Seismic Performance of Steel Plate Shear Wall Structural System

Structural systems with steel plate shear wall (SPSW) have been used in many tall buildings in the past decades. This system is particularly suitable for seismic regions because it can dissipate the seismic energy through the inelastic response of steel plate in shear. However, the relatively low lateral stiffness of the SPSW structural system in tall and slender buildings may result in excessive lateral drift and high seismic demands on vertical boundary elements (VBE). Placement of additional SPSW panels in the structure acting as outriggers could significantly reduce the lateral drifts and seismic demand on the VBEs by redistributing some of the overturning forces to adjacent columns. In this paper, a 40-story building is evaluated using steel plate shear wall structural system with and without outriggers. The outrigger panels are placed in 20th, 30th, and 40th story levels and the effectiveness of these elements on the overall seismic behavior is studied. Seven nonlinear time history analyses are carried out and the seismic performance of the structural system with outriggers is compared to the performance of the system without outriggers. The results indicate a significant reduction in lateral drifts and VBE seismic demands when the system is augmented with steel plate outrigger panels.

Flexural buckling of axially loaded concrete-infilled double steel corrugated-plate walls with T-section

This paper investigates the flexural buckling behaviour of axially loaded concrete-infilled double steel corrugated-plate-walls with T-section (T-CDSCWs). The T-CDSCW is composed of flange and web wall elements and vertical boundary elements. The wall element consists of two bolted-connected steel corrugated-plates with concrete infilled. The composite effect of the components in the wall element improves the load-bearing capacities of the T-CDSCW efficiently and leads to a thinner wall. Therefore, the failure mode of the T-CDSCW may be governed by global instability. With the web breadth relatively less than the flange breadth, the first-order elastic buckling mode of the T-CDSCW is flexural buckling about the asymmetric axis. The design issue of the flexural instability of the axially loaded T-CDSCW is investigated experimentally and numerically in this paper. The load-bearing and deformation behaviours were investigated by an experiment of the axially loaded T-CDSCW, based on which refined finite element (FE) models of T-CDSCWs are established and validated. The FE buckling analysis is carried out to investigate the elastic buckling behaviour of the T-CDSCW and propose the elastic flexural buckling load and the borderline between flexural and flexural-torsional buckling. Then, the inelastic flexural instability of the T-CDSCW is investigated by the FE nonlinear analysis, and influences of initial geometric imperfection are discussed. The normalized flexural slenderness ratio derived from elastic flexural buckling load delineates flexural instability pretty well and bases the design formulas of strength reduction factor. The design formulas proposed in this paper help to understand the axial load-bearing behaviour of the T-CDSCW.

Sectional strength design of concrete-infilled double steel corrugated-plate walls with T-section

This paper presents the sectional strength design method of concrete-infilled double steel corrugated-plate walls with T-section (T-CDSCWs). The T-CDSCW is composed of flange and web wall elements and concrete-filled steel tubes, where the former are formed by bolt-connected steel corrugated-plates and infilled concrete while the latter behave as vertical boundary elements. Load bearing capacities of T-CDSCWs are significantly improved by the favorable combination effect between bolt-connected steel corrugated-plates and infilled concrete in the wall elements. The failure mechanism and the sectional strength design of T-CDSCWs under combined axial compression and bending moment are focused analytically, experimentally and numerically, with an assumption of no consideration of overall instability of T-CDSCWs and local buckling of the steel corrugated-plates in the wall elements. An experiment of the T-CDSCW for sectional strength prediction was carried out, and a refined finite element (FE) model of the T-CDSCW was validated by the experimental results. Based on the FE model, parametric analyses of T-CDSCWs are performed to further investigate the effects of steel ratio and sectional geometry on the load-bearing capacities. It is found that T-CDSCWs under axial compression have completely different values of load-bearing capacities when they incorporate different bending direction moments. Based on experimental and numerical results, design formulas for predicting the sectional strength of T-CDSCWs under axial compression and bending moments are proposed, providing a preliminary structural design method of T-CDSCWs.

Strength design of concrete-infilled double steel corrugated-plate walls under uniform compressions

Concrete-infilled double steel corrugated-plate walls (CDSCWs) are composed of two steel corrugated-plates (SCPs) which are connected through bolts, and concrete filled the spacing formed between the two SCPs. Two vertical boundary elements are installed additionally at both sides of CDSCWs. On the one hand, the corrugated configuration of SCPs has great improvement on the load-bearing efficiency of CDSCWs; on the other hand, much higher bearing capacities and better seismic performance for CDSCWs are provided owing to the interactions among SCPs, bolts and infilled-concrete. This paper investigates the load-bearing mechanism and strength design formulae of CDSCWs under compressions. Since SCPs are prone to local buckling failure between two rows of bolts under the conditions of large vertical bolt spacing and small thickness of SCPs, this paper mainly focuses on the load-bearing mechanism of SCPs in CDSCWs under uniform compressions. The unilateral constraint on SCPs provided from infilled-concrete and the restraining effect on the flexural deformation of SCPs owing to bolts are considered. At first, series of finite element (FE) eigenvalue buckling analyses are conducted to study the elastic buckling behavior of SCPs subjected to uniform compressions. On the basis of Euler's formula, the formulae for predicting the elastic buckling stresses and corresponding normalized slenderness ratios λs of SCPs are achieved respectively. The instability performance of SCPs under uniform compressions is then investigated through FE nonlinear analyses, and accordingly the stability coefficient φs is attained. The corresponding φs−λs curve is therefore established in order to calculate the ultimate bearing capacities of SCPs. In addition, the cooperative performance of material strengths between SCPs and concrete is analyzed numerically when CDSCWs reach their compressive ultimate strength. With this consideration, the design method for predicting the cross-sectional strength of CDSCWs under compressions is proposed. Moreover, a CDSCW specimen with I-section is tested under a compressive load. Its cross-sectional strength is investigated experimentally. The results of the experiment coincide with those of numerical simulation, this verifying the safety and validity of the design method for cross-sectional strength design of CDSCWs.

Experimental cyclic test and failure modes of a full scale enhanced modular steel plate shear wall

Abstract Several studies on steel plate shear wall systems have shown that the seismic demand on the vertical boundary elements is extremely large for typical buildings. To overcome this problem, an enhanced approach is introduced in this paper. It involves utilizing not only a modular steel shear panel, but also contains column-independent boundary element which eventually facilitates retrofitting of the existing building. First, a four-story building was designed based on pushover analysis, followed by more accurate finite element analysis to refine the section design parameters. Next, a full scale single-story modular steel shear panel welded to the steel boundary elements was constructed and tested under cyclic load protocol to simulate the hysteresis behavior under severe excitations. The test results show a high initial stiffness, excellent ductility, and significant energy dissipation capacity. Observed failure modes were discussed.

Experimental investigations on seismic behavior and design of bottom vertical boundary elements in multi‐story steel plate shear walls

SummaryThis research investigates the seismic behavior and design method for the bottom‐level boundary columns, also called the vertical boundary elements (VBEs), in multi‐story steel plate shear walls (SPSWs). This paper firstly introduces the proposed design method for the bottom‐level VBE for the case when a frame swaying action causes the VBE to bend in single curvature, as is often seen in mid‐ and high‐rise buildings. Two 12‐story (12F) prototype SPSWs were designed using the proposed design method. Two 40%‐scale substructural test specimens representing the first 2.5 stories of the 12F SPSW prototype designs were cyclically tested with the Multi‐Axial Testing System at the Taiwan National Center for Research on Earthquake Engineering in 2013. The test results confirm the effectiveness of the proposed design method in predicting the yielding of the top end of the bottom VBE. In addition, test results show that the lateral torsional buckling of the bottom VBE could occur after the VBE top end yields, indicating that premature top‐end yielding should be prohibited for the bottom VBE before the SPSW develops uniform yielding mechanism under the lateral forces.

Overall instability performance of concrete-infilled double steel corrugated-plate wall

This paper proposes a new type of composite walls, namely concrete-infilled double steel corrugated-plate walls (CDSCWs). The CDSCW consists of a wall element that is formed by two steel corrugated-plates, where they are interconnected through high-strength bolts, and the spacing between the two steel corrugated-plates is filled with concrete. Additionally, two concrete-infilled steel tubes (CFSTs) are assigned as vertical boundary elements at both sides of the wall element. Not only the corrugated configuration of steel sheets themselves would significantly improve the load-bearing efficiency of CDSCWs, but also the interactions and combined actions among steel corrugated-plates, high-strength bolts and concrete could provide much better load-bearing capacity and seismic performance for CDSCWs. In addition, industrial mass production of the CDSCWs can be achieved by adopting integrated cold-formed steel rolling techniques. Therefore, the CDSCWs are much more suitable for applications in high-rise building structures as shear wall structural systems that carry axial loads and bending moments as well as shear loads. This paper mainly investigates the overall instability performance of I-section CDSCWs under uniform compressions and corresponding design formulae are recommended. Firstly, Finite Element (FE) eigenvalue buckling analyses are carried out to investigate the overall elastic buckling behavior of CDSCWs subjected to vertical compressive loads. The formulae for estimating the elastic buckling loads of CDSCWs and corresponding normalized slenderness ratios λn are obtained based upon the form of Euler's formula. The overall instability performance of CDSCWs under compressions is then studied by FE nonlinear analyses, leading to the overall stability coefficient φ as well as φ-λn curve for their strength design. Moreover, an I-section CDSCW specimen has been designed and tested under uniform compressive load, and its overall instability performance is investigated experimentally. The results obtained from the experiment show an agreement with those obtained from FE numerical analyses, which also verifies the safety and validity of φ-λn curves for the strength design of CDSCWs.

Nonlinear Finite Element Modeling of Novel Partially Connected Buckling-Restrained Steel Plate Shear Walls

It has been demonstrated that the buckling-restrained steel plate shear wall (SPSW) is an efficient and economic lateral load-resisting system exhibiting high performance on initial stiffness, ductility, shear resistance, and energy dissipation capacity. In present study, a novel partially connected buckling-restrained SPSW is presented to reduce the stiffness requirement for the vertical boundary elements. Meanwhile, nonlinear finite element (FE) analysis is performed to evaluate the behavior of the proposed shear wall system so that a large expense of conducting additional test can be saved. The experimental results from the literature and the test conducted by the authors are used to establish the validation of FE models. Based on the validated FE models, a further extensive parametric study is carried out to investigate the effect of initial imperfection, stiffness of boundary elements, slenderness ratio (Height/Thickness) of the infill panel, aspect ratio (Height/Width) of the infill panel, RC cover panel thickness and bolt spacing on the behavior of the partially connected buckling-restrained SPSW.

Experimental and Numerical Research on Steel Plate Shear Wall with Infill Plate Connected to Beam Only

Steel plate shear walls consist of thin infill steel plates attached to beams, called (horizontal boundary elements, HBEs), and columns (vertical boundary elements, VBEs) in structural steel frames. The thin unstiffened web plates are expected to buckle in shear at low load levels and develop tension field action, providing ductility and energy dissipation through tension yielding of the web plate. HBEs are designed for stiffness and strength requirements and are expected to anchor the tension field formation in the web plates. VBEs are designed for yielding of web plates and plastic hinge formation at the ends of the HBEs. This design approach may result in very large demand on boundary frame members, especially VBEs in most cases. Several methods such as using LYP, perforating the infill plate and omitting connection of infill plate to columns have been proposed to reduce the moment and axial force demands on the VBEs. Study the behavior of steel plate shear walls omitting the connection of infill plate and columns is the main purpose of this research. A classic analysis base on PFI method along with quasi static cyclic experimental study has been performed in order to investigate the behavior of such a system. The results of the experimental study are used to verify numerical models. Behaviors of proposed system (overall capacity and initial stiffness) were compared with those of the conventional SPSWs. Results show that both parameters are reduced in comparison to the conventional SPSWs.

Performance of steel plate shear walls with axially loaded vertical boundary elements

This paper presents a study of the applicability of the flexibility coefficient limit for vertical boundary elements (VBEs) in steel plate shear walls (SPSWs). One 1/3-scale, one-bay, and two-storey SPSW specimen was tested under quasi-static cyclic loading. The specimen had the flexibility coefficient and axial load ratio of the VBEs of 2.2 and 0.3, respectively. The results show that axial loads on the VBEs exacerbate the failure of SPSW structure. At the drift ratio of 0.9%, VBEs subjected to the axial load of 0.3fyAg exhibited considerable inward deformation equivalent to 1/400 of the column height. Besides, a finite element model (FEM) of SPSW structure was established and validated by test results. A parametrical study of SPSW specimens with various width-to-height ratios of infill steel plates and axial load ratios of VBEs was subsequently conducted by the FEM. The influence of VBEs with different axial loads on the structural performance of SPSWs was also discussed. Without considering the effect of axial load, the VBE flexibility coefficient limit of 2.5 is applicable for the SPSWs with the width-to-height ratio of 1.0 for the infill steel plate. However, with an increase of the width-to-height ratio of the infill steel plate, the development of the tension field tends to be inadequate, while the shear capacity and stress uniformity of the infill steel plate decrease. As a result, the flexibility coefficient limit of 2.1 is recommended for the design of VBEs in SPSW structures. Contrarily, considering the axial load effect, axial loads acting on the VBEs significantly decrease the shear capacity and stress uniformity of SPSWs with levels depending on the width-to-height ratio of infill steel plates and the flexibility coefficient of VBEs. To fully develop the tension field in infill steel plates for lateral resistance of SPSWs, axial load ratio, width-to-height ratio, and column flexibility coefficient should be taken into consideration in the design of SPSW structures.

Behaviour of Steel Plate Shear Wall in Multi Span Moment Frame with Various Infill Plate Connection to Column

Steel plate shear walls consist of thin infill steel plates attached to beams, called (horizontal boundary elements, HBEs), and columns (vertical boundary elements, VBEs) in structural steel frames. The thin unstiffened web plates are expected to buckle in shear at low load levels and develop tension field action, providing ductility and energy dissipation through tension yielding of the web plate. HBEs are designed for stiffness and strength requirements and are expected to anchor the tension field formation in the web plates. VBEs are designed for yielding of web plates and plastic hinge formation at the ends of the HBEs. This design approach may result in very large demand on boundary frame members, especially VBEs in most cases. Several methods such as using LYP, perforating the infill plate and omitting connection of infill plate to columns have been proposed to reduce the moment and axial force demands on the VBEs. The main purpose of this research is to study the behavior of steel plate shear walls with various connection of infill plate to columns in multi span moment frames. A numerical study has been performed in order to investigate the behavior of such a system. The results of proposed system were compared with those of the conventional SPSWs. Results show that reducing the infill plate connection to columns will reduce the axial forces in columns.

Strip Model Analysis for Steel Plate Shear Walls in Earthquake Resistant Structures

Unstiffened Steel Plate Shear Walls (SPSWs) are very effective structural systems designed to resist lateral forces. SPSW systems consist of thin web plates infilled within frames of steel horizontal and vertical boundary elements. The thin unstiffened web plates are expected to buckle in shear and to develop diagonal tension field after buckling under the action of horizontal loads. For unstiffened steel plates, buckling in shear occurs in the elastic range at low stress levels. This behaviour provides strength, stiffness and ductility and allows to have an appropriate level of energy dissipation through tension yielding of the web plates. This paper assesses the inelastic structural response and behaviour of Steel Plate Shear Wall systems using both a modified strip model approach and a new simplified strip model for only beam connected SPSWs. Both models are developed with plasticity concentrated elements and the performed analyses include the nonlinear behaviour of strips, also considering the compressive forces effects over the strip model elements. This research indicates fundamental aspects of the seismic performance of Steel Plate Shear Wall systems, such as energy dissipation capacity, panel ductility demand, seismic inter-story drift and design load demands in Vertical Boundary Elements (VBE) and Horizontal Boundary Elements (HBE) of the frame. The results obtained from the use of these models are compared with selected experimental and numerical results to enrich the research conclusions.

Full-Scale Cyclic Testing of Self-Centering Modular Panels for Seismic Resilient Structures

This paper presents a new seismic load-resisting system termed self-centering modular panel (SCMP) which provides lateral stiffness and self-centering stiffness for tension-only concentrically braced beam-through frames (TOCBBTFs). The SCMP is a posttensioned (PT) steel moment resisting frame, which consists of horizontal boundary elements (HBEs), vertical boundary elements (VBEs) and PT strands. The self-centering stiffness is provided by the PT HBE-to-VBE connections. Specimens of original TOCBBTF and TOCBBTF with SCMP were tested to investigate the function of the SCMP. The test results show that compared to the original TOCBBTF, the TOCBBTF with SCMP was capable of recentering after 4% drift of loading. Moreover, after severe cyclic loading and replacement of the damaged bracings, the repaired TOCBBTF with SCMP exhibited almost identical stiffness, strength and recentering ability to that of the original system.

Seismic behaviour of steel plate shear wall systems with staggered web configurations

SummaryUnstiffened steel plate shear walls (SPSWs) are used as lateral load‐resisting systems in building structures. The energy dissipation mechanism of SPSWs consists of the tension yielding of web plates and the formation of plastic hinges at the ends of horizontal boundary elements. However, vertical boundary elements (VBEs) of high‐rise SPSWs may experience high axial forces under lateral loading. This study explores the effectiveness of staggering of web plates on the reduction of VBE forces and drift response of SPSWs during an earthquake event. An analytical study has been conducted to determine the base shear reduction factor so as to match the overstrength of staggered systems with conventional SPSWs. A design methodology has been proposed for staggered SPSWs. Six‐, 9‐, and 20‐storey staggered and conventional SPSWs with varying aspect ratios are considered in this study to compare their seismic response. These study frames are modelled and analysed in OpenSEES platform. Nonlinear static and dynamic analyses are performed to compare the drift response, hinge mechanisms, and steel tonnage. Staggered SPSWs showed uniform drift distribution and reduction in interstorey drift and axial force demand on the VBEs.

11.43: Seismic performance of staggered steel plate shear wall systems in high rise buildings

ABSTRACTUnstiffened Steel Plate Shear Walls (SPSWs) are used as the lateral load‐resisting systems in building structures. The energy dissipation mechanism of SPSWs is consisted of the tension yielding of web plates and the formation of plastic hinges at the ends of horizontal boundary elements (HBEs). High‐rise buildings experience the high overturning moments leading to the high axial demands in the vertical boundary elements (VBEs) of SPSWs. The presence of high axial forces in VBEs can cause a reduction in their flexural capacity resulting in the drift concentration or even soft‐story mechanisms in the lower storey levels during an earthquake event. Past studies have shown that a staggered arrangement of steel plates may help in reducing the force demand in VBEs. Two simple methods are investigated in this study to r b educe the VBE forces are (i) by increasing the width of the web plates and (ii) by staggering the web plates over the frame height. A 20‐story steel frame building has been considered as the study frame. Three types of systems are designed to study the effect of aspect ratio and staggering on the seismic behaviour of SPSW. Force‐displacement characteristic of SPSW used in the numerical model is validated with the test results. Both nonlinear static and dynamic analyses are carried out in this study. Axial and shear force demands in the VBEs are reduced for the study frame, while achieving the desired hinge mechanisms. Nonlinear dynamic analyses under twenty spectrum‐compatible design‐level ground motions exhibited that staggered steel plate shear wall systems reduced the inter‐story drift by about 50% with respect to their conventional counterpart.

Shear resistance of buckling-restrained steel plate shear walls

The buckling-restrained steel plate shear walls (SPSWs), which consist of a steel plate sandwiched in between by two reinforced concrete (RC) cover plates, are known to be a robust and efficient lateral load-resisting system. Since the initial imperfection between the RC plates and the inner plate which is mainly caused by the fabrication and construction errors, the high-order buckling deformation generally forms in the compression zone of inner steel plate. Therefore, a modified method based on the high-order buckling analysis on the inner panel is developed to predict the shear resistance of buckling-restrained SPSWs in the present study. Furthermore, the available experimental data from literature is employed to establish the validation of the modified method, and the shear resistance predicted by the proposed method reasonably agrees with the test results. In addition, the effect of the flexural stiffness of vertical boundary elements (VBEs) is also investigated. The minimum moment of inertia of VBEs is then proposed so that the inner steel plate fairly uniformly forms the tension field. Moreover, the pushover analysis is conducted using nonlinear finite element (FE) method to establish the validation of the proposed VBEs flexural stiffness. The FE results are then compared with that predicted by the proposed method and a reasonable agreement is generally achieved between them.

Flexural behavior of anchor horizontal boundary element in steel plate shear wall

Steel plate shear walls (SPSWs) have been increasingly used in lateral load resisting system since the post-buckling strength of web plates was realized and considered in practical design. Diagonal tension field is formed in the web plate to resist the lateral force induced by winds and earthquakes. The force is anchored by the surrounded horizontal boundary elements (HBEs) and vertical boundary elements (VBEs) and eventually transferred to the ground. Therefore, the response of HBEs, especially anchor HBEs, is essential to ensure that SPSWs could exhibit the required strength, ductility, and energy dissipation capacity. This paper presents the results of theoretical studies into the flexural behavior of the anchor HBEs of SPSWs and can be regarded as an extension to the previous work by Qu and Bruneau (2011) and Qin et al. (2017). The boundary effect was considered to reflect the actual stress state at the HBE-to-VBE connection, which assembled the method by Qin et al. (2017). Furthermore, more proper distributions of the vertical component of tension field for the positive and negative flexure cases, respectively, were proposed comparing to the work by Qu and Bruneau (2011). The hand calculation approach for the plastic flexural capacity of the anchor HBEs was given by the summation of the contributions from the flanges and the web. The developed equations are compared with previous data and good agreement was found between them. Meanwhile, comprehensively discussions are conducted to evaluate the influence of key parameters on the flexural behavior of anchor HBE. It was found that the plastic flexural capacity of anchor HBE decreases from unity to the minimum as a result of the increase in shear force, axial force and vertical stresses. Moreover, the flexural response of anchor HBE is most vulnerable to the change in shear force. This indicates that boundary effect is significantly important and cannot be ignored in the analysis. The research in this paper provides basis for the capacity design of anchor HBE.