Unstiffened Steel Plate Shear Walls Research Articles

Cyclic Behavior of New Steel Plate Shear Walls Reinforced with Trapezoidal Corrugated Plates

Unstiffened steel plate shear walls have low buckling strength, which caused development diagonal tension field under lateral load. Corrugated plates have higher out-of-plane stiffness and improved buckling stability. Combining corrugated and flat plates in steel shear wall web could be effective. In this paper a new steel shear wall system reinforced with trapezoidal corrugated steel plates were proposed. In this study, the behavior of the system was experimentally studied under cyclic loading. Four specimens with the one-third scale were evaluated, which were control unstiffened specimen, the specimen with vertical 45° trapezoidal corrugated web, specimen with a corrugated web plate reinforced with two flat plates, and specimen with a flat web plate reinforced with two corrugated plates. In all four specimens, the total thicknesses of steel plates were the same; therefore, the thickness of each plate in specimens with three plates was one-third of the specimen with one plate. The studied parameters were the bearing capacity, maximum base shear, stiffness, ductility, energy absorption, and modification factor for the dissipation capacity of the specimens. The results revealed the maximum lateral load capacity of specimen with a flat web plate reinforced with two corrugated plates increased about 17%, 37%, and 19%, comparly to unstiffened specimens, vertical 45° trapezoidal corrugated web, and corrugated web plate reinforced with two flat plates, respectively. According to the results, the behavior of the seismic parameters of the proposed specimen with a flat web plate reinforced with two corrugated plates was clearly better than that of the other specimens.

Experimental and numerical investigation of a new type of steel plate shear wall with diagonal tension field guiding stiffeners

A novel type of steel plate shear wall for withstanding lateral forces was proposed. Inclined stiffeners (acting as tension field guiding stiffeners) were added at the corners of the shear wall and a middle link beam was created, similar to the eccentrically braced frames (EBF). Therefore, upon adding diagonal members to the shear wall, the system resembled a combination of a steel plate shear wall system with an EBF system.To study the cyclic performance of the system equipped with the guiding stiffeners, a scaled specimen of the shear wall was made and subjected to cyclic loading. Finite element model of the wall was simulated and validated using the corresponding laboratory data. Then, a comparison between the proposed shear wall and the corresponding unstiffened steel plate shear wall was made. In the proposed system, the guiding stiffeners can alter the pattern of the tension field, pushing away the plastic strains from the column face toward the link beam. This helps the columns and connections remain intact. As a result, the system failure mechanism includes two-stage ductile fuses, including the steel plate yielding in tension, and flexural stresses or shear plastic hinges at the link beam ends. Compared to the unstiffened steel shear wall, the fuses help dissipate more energy in the proposed shear wall. In general, diagonal tension field guiding stiffeners can enhance the lateral force capacity, ductility, energy absorption, and stiffness of the system simultaneously.

Mechanical Behavior of Two-Side Bolted Steel Plate Shear Wall Considering Top-Seat Constraints with Frame Beams

A steel plate shear wall (SPSW) is a useful component for resisting lateral action. To improve the performance of frame columns, some studies focus on a two-side connected SPSW, in which the wall plate is not connected with the frame columns. However, few studies conducted on a two-side connected SPSW consider the effect of frame constraints or the connections between the infill plates and frame beams. In this study, by using finite element modeling (FEM), two unstiffened SPSW models with two-side fixed connections and six unstiffened SPSW models with two-side bolt connections were simulated. Their performance under the presence of out-of-plane frame beam flange constraints and different numbers of bolts between the infill plates and frame beams was analyzed. The mechanical performances such as hysteretic behaviors, the capacity of energy dissipation and the out-of-plane deformation of the members were investigated by applying monotonic and cyclic loading. The results revealed that non-negligible deformation would be generated at the lateral border of the bolt connections and that the out-of-plane deformation of the frame could be significantly affected by constraints. These findings can guide the engineering design of SPSWs in the future.

Topology Optimization of Stiffened Steel Plate Shear Wall Based on the Bidirectional Progressive Structural Optimization Method

Many studies on structural topology optimization of steel plate shear walls have been conducted. However, research on topology optimization using the bidirectional evolutionary structural optimization method is limited. Accordingly, this study optimized the topology of the stiffening effect of steel plate shear walls (SPSWs) based on this method. A finite element model of the SPSW was established using Abaqus software through the “sandwich” modeling method. An optimization region was expanded into two optimization regions. As the optimization targets, SPSWs with different aspect ratios were selected. Elastoplastic optimization of a single-layer SPSW was performed through the horizontal displacement cyclic loading, and the distribution law of the stiffening effect was obtained. The stiffeners on the SPSW were arranged according to the SPSW-A075 scheme. Monotonic and reciprocating loading simulation tests were performed on the unstiffened SPSW and common transverse and longitudinal stiffeners to analyze their mechanical properties. The results show that the optimized layout of the stiffened SPSW demonstrated better seismic performance and energy dissipation capacity. The buckling bearing capacity increased by 2.17–2.61 times, and the stiffness and initial stiffness improved significantly.

Hysteretic behavior of partially buckling-restrained steel plate shear walls with coupled restraining steel tubes

This paper presents a new partially buckling-restrained steel plate shear walls (PBRSPSWs) that used coupled restraining steel tubes (CRSTs) as buckling restraining members. Compared with traditional restraining panels, CRSTs have the advantages of small cross-section, light-weight, and stable buckling restraining effect. Quasi-static tests of four specimens under the cyclic load were carried out to investigate the seismic performance of PBRSPSWs with CRSTs. Test results prove that CRSTs serve well as effective buckling restraining members in PBRSPSWs. Compared to unstiffened steel plate shear walls (USPSWs), the bearing capacity of PBRSPSWs with CRSTs increases by 6% to 21%. The accumulative dissipated energy at 2% story drift of PBRSPSWs with CRSTs increases by 23% to 101%. The ductility factor of PBRSPSWs with CRSTs ranges from 3.9 to 5.9. Furthermore, the finite element (FE) method is applied to simulate the hysteretic behavior of PBRSPSWs. FE analysis demonstrates that both the bearing capacity and energy dissipation capacity of PBRSPSW increase with the decrease of the height-to-thickness ratio of unstiffened zones, then remain unchanged when the height-to-thickness ratio of unstiffened zones is smaller than 30. The maximum gap between the restraining member and the steel plate is suggested to be half of the thickness of the steel plate. Finally, a formula for calculating the bearing capacity of PBRSPSWs is developed and validated by the test results.

Seismic performance investigation of an innovative steel shear wall with semi-rigid beam-to-column connections

Steel plate shear walls (SPSWs) are a robust lateral load resistance structure because of their high ductility and efficient energy dissipation when subjected to seismic loads. This research investigates the seismic performance of an innovative infill web strip (IWS-SPSW) and a typical unstiffened steel plate shear wall (USPSW). As a result, two 1:3 scale specimens of an IWS-SPSW and USPSW with a single story and a single bay were built and subjected to a cyclic lateral loading methodology. In the prototype, semi-rigid end-plate connectors for the beam-to-column connections were utilized. The test result of IWS-SPSW showed outstanding ductility and shear load-bearing capacity without cracks or damage. Additionally, the IWS-SPSW exhibited strong energy dissipation without substantial beam-column connection distortion. USPSW showed excellent shear load-bearing capacity, low ductility, extensive infill plate corner tearing, and large infill web plate cracks. The FE models were developed and verified against experimental data. It has been shown that the infill web strips can affect the high performance and overall energy dissipation of an SPSW system. In addition, a parametric study was conducted to investigate the infill web strip material properties, such as steel strength and thickness, that can significantly enhance the system’s seismic performances.

Effect of Column Flexural Stiffnesses on the Seismic Performance of Stiffened Steel Plate Shear Walls

Two types of lateral resistance structural systems, namely unstiffened steel plate shear walls (USPSWs) and stiffened steel plate shear walls (SSPSWs), are typically used in high-rise structures. Numerous experimental and numerical studies have been conducted on the structural performance of SSPSWs. However, few studies have been conducted to investigate the effect of column flexural stiffness on SSPSW systems. In this study, an analysis and numerical investigation of SSPSWs with variable column flexural stiffnesses was performed. The hysteretic performance, secant stiffness reduction and energy dissipation of SSPSWs with four column flexural stiffnesses were investigated. The column flexural stiffness reduction in the USPSWs and SSPSWs did not negatively influence the overall performance of drift ratios up to 2.5%. Moreover, the infill plates of the USPSWs and SSPSWs could achieve the ultimate strengths similar to the theoretical values despite the column not satisfying the minimum flexural stiffness requirements from CSA S16-09 and PEER/ATC72-1, which indicated that these requirements could be conservative.

Effect of Welding Separation Characteristics on the Cyclic Behavior of Steel Plate Shear Walls

Currently, the steel plate shear wall (SPSW) is commonly used in high-rise steel buildings as a lateral load-resisting system due to its several advantages such as its lightweight and high ductility and strength. The SPSW consists of two main parts, i.e., the boundary frame and infill plate, which are connected by welding. The objective of this work is to study the effect of the infill plate weld separation on the seismic behavior of the SPSWs. A numerical method was proposed to have a comprehensive comparison of seismic behaviors of different separation characteristics. The model was validated by using previously published experimental works. Key parameters, such as load-carrying capacity, stiffness, and energy-dissipation capacity, were discussed extensively. The unstiffened SPSW (USPSW) system is more sensitive to the plate–beam separation than the plate–column one, especially the corner plate–beam separation. When plate–column welding separation occurs, the initial stiffness and the energy dissipation capacity are reduced by approximately 21% and 14%, respectively; however, the reductions are 36% and 20.5% in the case of beam welding separation.

Topology and shape optimization of steel plate shear walls for enhancing the seismic energy dissipation capacity

In recent years, steel plate shear walls (SPSW) have been considered as one of the reliable passive seismic-resisting systems, which are classified into two general categories of stiffened and unstiffened types. Unstiffened SPSWs experience early buckling at low shear loads and hence, the pinching occurs in obtained hysteretic curves and this event significantly reduces the amount of dissipated seismic energy. To address this issue, this paper aims to optimize the performance of unstiffened SPSWs considering different loading conditions and achieve an optimized SPSW with a simple configuration and no need for additional buckling-restrained plates. For this purpose, after validation of the finite element modeling and optimization procedures by ABAQUS, optimized SPSWs were obtained considering the strain energy as the objective function along with the plate volume and planar symmetry as the constraints. Then, all the obtained configurations were superimposed using AutoCAD and a final optimized configuration was proposed. The cyclic performance of unstiffened, ring-shaped and optimized SPSWs with the same weight was evaluated under a quasi-static cyclic loading protocol. Finally, the models of two 5-story building frame systems equipped with unstiffened and optimized SPSWs were subjected to Tabas, Manjil and Bam records to investigate their seismic performance. Based on the obtained results, it was concluded that the performance of the introduced optimized SPSW improved in all cases compared to the ring-shaped SPSW and it can be a reliable alternative to this type of SPSW.

Interaction behaviour of buckling-restrained steel plate shear wall and boundary composite frame

Both concrete-filled steel tube (CFST) column and buckling-restrained steel plate shear wall (BRSPSW) have the advantages of high load-carrying capacity and superior seismic performance. The structural system composed of CFST columns and BRSBSWs will have the superior mechanical performance and be more suitable for high-rise buildings. In this study, the pseudo-static tests were carried out on the specimens of unstiffened steel plate shear wall and cold-formed steel (CFS) BRSPSW which were infilled in the single-span two-story 1/3 scaled composite frame respectively. The test results show that the CFS stiffeners have the obvious effect of restraining the outward buckling deformation on the steel plate, improving the lateral stiffness and resistance of the steel plate, and reducing the deflection deformation of the steel plate to the surrounding composite frame. The finite element (FE) model was established and validated, and the interaction between the BRSPSW and the composite frame was analysed. In combination with the theory and the FE analysis results, the maximum deflection limits of CFST column and steel beam were proposed to ensure the strength of the infill BRSPSW to give full play. Considering the separation of the steel tube wall of square CFST from the core concrete in the process of loading, the deflection limit of square CFST is proposed considering the separation effect of the steel tube wall of square CFST from core concrete under the action of infilled steel plate.

Comparative response assessment of different steel plate shear walls (SPSWs) under near-field ground motion

Steel plate shear walls (SPSWs) are widely used due to their high energy absorption and exceptional lateral resistance. However, the behavior of different infill panels varies, and their response under near-field seismic excitations is uncertain. To better understand how different infill panels contribute to seismic structural responses, this paper presents findings from research conducted on different types of SPSWs. The study of different types of SPSWs with infill panel aspect ratios of 1:1 and 2:1 under cyclic loading was the first part of this parametric investigation, and the second part was the study of the structural response of 3D frames with an aspect ratio of 3:4:2 and a 1:1 infill panel under near-field ground motions. The results of energy dissipation, acceleration, and drift were compared. This study's goal was to better understand how various infill panels react to near-field ground motions and cyclic loading. With a 2:1 aspect ratio, unstiffened SPSWs reduced plastic dissipation by 78% while increasing lateral stiffness by 10%. With minimal peak transient and residual interstory drifts and effectively damped floor acceleration, unstiffened SPSW demonstrated the best viscous effect and dissipated 69.42% of the total system.

A closer look at numerical simulation of self-centring steel plate shear walls

Unstiffened steel plate shear walls (SPSWs) are one of the most efficient lateral resisting systems in conventional steel structures. The essential characteristics of SPSWs, including high initial stiffness, great ductility and low compression resistance, make them desirable for implementation in self-centring structures that aim to eliminate or effectively reduce residual drift under earthquake load. In this work, a numerical simulation of a self-centring SPSW based on the strip model published by the American Institute of Steel Construction was conducted and an attempt was made to modify the method to match experimental results more accurately. It was found that the compression resistance of shear wall strips, realistic pinching behaviour and energy dissipation of bolts in post-tensioned connections are key aspects for developing a reliable simulation of a self-centring frames with SPSWs. Neglecting any of these issues can distort evaluation of the self-centring capability and the dissipated energy in the frame. In addition, deterioration in the shear wall material due to web plate tearing needs to be considered in the modelling to achieve more realistic assessments of the ultimate stiffness and strength of the system under significant seismic loads.

Experimental and numerical study on the structural performance of auxetic-shaped, ring-shaped and unstiffened steel plate shear walls

Structural engineers have always tried to enhance the seismic performance of existing building systems by introducing new solutions to increase the amount of ductility along with dissipated seismic energy. In this regard, this paper presents a new system to improve the structural behavior of unstiffened steel plate shear walls and eliminate the known defects of these efficient seismic-resistant systems. One of the significant drawbacks of unstiffened steel plate shear walls is the pinching of their hysteretic curve that happens due to the early out-of-plane buckling of the infill plate under small shear forces. Therefore, the primary purpose of this study is to reduce the amount of out-of-plane buckling using perforated plates with periodic auxetic-shaped cellular forms, which have a negative Poisson's ratio. To this aim, a parametric study is conducted on 255 finite element models of auxetic-shaped steel plate shear walls using ABAQUS software to select the most efficient configuration considering some design parameters such as the amount of out-of-plane buckling, energy dissipation and strength. Then, two full-scale specimens of the selected models are investigated experimentally under a quasi-static cyclic loading history. Finally, regarding this fact that for broader adoption of a new system, besides its structural performance, the total weight of that structural system is a determinant factor, two 5- and 10-story plane building models with unstiffened and auxetic-shaped steel plate shear walls are designed to have the life safety performance level at the BSE-1 hazard level and they are evaluated by performing nonlinear static analyses. The results show that auxetic-shaped steel plate shear walls, while improving the seismic performance of a building, reduce its weight.

Response assessment and prediction of low yield point steel plate shear walls with curved corrugated web plates and reduced beam sections

In recent years, researchers have been moving increasingly towards new lateral force-resisting systems such as corrugated, low yield point (LYP) steel plate shear walls (SPSWs) fabricated with reduced beam sections. Recent application of curved corrugated web-plates with improved structural performances combined to the merit of LYP steel with superior elongation capacity has motivated the researchers to consider the employment of such elements in unstiffened SPSWs with the aim of developing a high-performing system. Currently, no design code addresses the seismic performance of LYP corrugated steel plate shear walls (CSPSWs). More investigations are required to develop a fundamental understanding of the performance of these seismic systems employing LYP steel material and corrugated infill plates. The present paper investigates the seismic performance of unstiffened, corrugated, and LYP steel walls under monotonic and cyclic loadings. A series of LYP steel plate walls were designed based on the capacity design approach proposed in AISC 341 code. The effectiveness of web plate thickness, corrugation angle, number of corrugations, and the aspect ratio of the plate are evaluated in this study. The results of this research demonstrate how employment of LYP steel material as well as curved corrugated plates is beneficial in improving the strength, hysteresis performance, and stiffness of the system. Increasing the number of corrugation half-waves can adversely affect structural behavior. The behavior of LYP steel plate shear walls with curved corrugated web plates is predicted and examined using a modified plate-frame interaction (M-PFI) method. Analytical predictions are compared with experimental and numerical results.

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.

Analysis on the Behaviour of Stiffened and Unstiffened Steel Plate Shear Walls with Enhanced Performance

Steel Plate Shear Walls (SPSWs) are utilized for frameworks apposing lateral load for new as well as retrofit developments. For the most part, the shear walls made of thin plates are utilized, however for smaller loads it exhibits buckling resulting in a hysteretic behavior that is highly pinched. So as to lessen the buckling, holes are made in steel plate. Most of the studies provide either a circular or a rectangular hole in the steel plates. Hence we propose an elliptical hole which would improve the performance of the SPSW. This study develops and analyses the performance of a stiffened and unstiffened SPSW model with and without opening in the steel wall.

Stiffness Demand on Stiffeners of Vertically Stiffened Steel Plate Shear Wall

Elastic buckling of steel plate shear walls (SPSWs) vertically stiffened by either flat-bar or closed-section stiffeners is studied first to determine the required bending stiffness on stiffeners. The torsional stiffness of the stiffener is found to increase the buckling stress and reduce the required bending stiffness. The proposed equation for the elastic threshold stiffness is related to the increment of the elastic buckling stress of stiffened SPSWs over that of unstiffened SPSWs. Comparisons with previous research on stiffened plates are presented. For moderately thick and stocky plates, elastic-plastic buckling stress is used to define the threshold stiffness. It is found that the threshold stiffness based on elastic-plastic buckling stress is less than that based on elastic buckling stress. Replacing the elastic buckling coefficients with elastic-plastic buckling coefficients, the proposed equation gives good predictions for elastic-plastic threshold stiffness. The findings of this study may be helpful in understanding the real demand on stiffeners in stiffened SPSWs.

A Study on Steel Plate Shear Wall

The main objective of this research study was to evaluate the parameters of stiffened and unstiffened steel plate shear wall under seismic loads. The scope of effort included simulating five unstiffened steel plate shear wall with varying thickness, three singly stiffened steel plate shear wall, and three doubly stiffened steel plate shear wall. The validation and simulation was done using software package ANSYS v16 using loads derived from ETABS. Overall, Unstiffened steel plate shear walls produced high in-plane and out of plane displacements which decreased with increase in thickness of plate; than singly stiffened followed by doubly stiffened steel plate shear walls. With introduction of stiffener in steel plate shear wall, the in-plane displacement values reduced by about 1%, and about 3% when doubly stiffened on the other hand the out of plane came down by 50% when stiffened singly and also when doubly stiffened. It was noteworthy that stiffener does not play any significant effect on any parameter except for out of plane displacement.

Seismic collapse assessment of stiffened steel plate shear walls using FEMA P695 methodology

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.

Experimental Study of Composite Steel Plate Shear Wall with Flush End-Plate Connection

This paper presents an investigation on the structural performance of steel plate shear wall (SPSW) with flush end-plate beam–column connections and infill precast reinforced concrete (precast RC) panels. Two single-span two-story SPSW specimens, including unstiffened SPSW (NBRP) and precast RC panel restrained SPSW (Con-BRP), are first tested, followed with a parametric study by finite element method. Precast RC cover panels are installed on both sides of the infill steel plate and are disconnected from steel frame. Test results indicate that the use of precast RC cover panels increases the load carrying and energy dissipation capacities of the SPSW structure, but decreases its ductility. It is also effective in reducing the inward flexural deformation of columns. Moreover, the stiffening effect of the infill steel plate on the beam–column connections remains, which is a result of the precast RC cover panel’s resistance to the local buckling and the tears of the infill steel plates. The influence of the gap size between the precast RC cover plate and frame members on the failure mode of the specimen Con-BRP is also investigated, based on which a maximum gap size is recommended. Conclusions are drawn that SPSW structure with flush end-plate beam–column connections and precast RC cover panels fully exploits the strength of infill steel plates and exhibits excellent structural performance.