Behavior Of Shear Walls Research Articles

Study on Seismic Behavior and Component Vulnerability of Corroded RC Shear Walls Subjected to Flexural Shear Failure

ABSTRACT The impact of corrosion degree, axial compression ratio, reinforcement ratio of longitudinal bar and horizontal distribution rebar, and stirrup of boundary column on seismic performance of RC shear walls were investigated. The corrosion forms (rust expansion cracks and corroded steel bars), failure process, hysteretic characteristics, bearing capacity, and deformability were compared. Subsequently, a numerical model of corroded RC shear walls was established adopting shell elements. Finally, according to the numerical simulation method, considering the uncertainty of corrosion degree and material parameters, the vulnerability models of RC shear wall components with different corrosion degrees were built. The results show that the mechanical properties of the shear wall were seriously deteriorated due to the corrosion of steel bars, and the ultimate displacement and ductility coefficient of severely corroded specimens were reduced by 28.5% and 12.27% respectively, compared to non-corroded specimens. A proposed numerical modeling method for corroded RC shear walls based on shell element is accurate, and the bearing capacity error and energy dissipation error of the simulation and test results were less than 20%. As the degree of corrosion grew, the probability of shear wall components experiencing more severe failure added significantly. When the displacement angle was 1/120 (This is the limit value of elastic-plastic displacement angle specified in the code), the probability of DS3 and DS4 occurring in the shear wall with a corrosion degree of 0% were 56% and 39.44%, and the probability of DS4 and DS5 occurring in the shear wall with a corrosion degree of 10% were 41.1% and 38.44%.

Experimental and numerical investigation on seismic performance of SFRC shear walls with CFRP bars

In order to investigate the seismic performance of steel fiber reinforced concrete (SFRC) shear walls with CFRP bars, quasi-static tests were conducted on six full-scale shear walls with a shear span ratio of 2.0, including one steel bars reinforced ordinary concrete (RC) shear wall, one CFRP bars reinforced ordinary concrete (CRC) shear wall and four CFRP bars reinforced SFRC (CSFRC) shear walls. The variables included steel fiber volume fraction (SFVF), axial load ratio and concrete strength grade. The experimental results showed increasing the SFVF could significantly decrease the concrete damage level and improve repairability. Meanwhile, the bearing capacity, ductility, and energy dissipation capacity all improved, and the stiffness degradation slowed. Compared to RC shear wall, the peak load of the CSFRC shear wall with SFVFs of 0 %, 0.75 % and 1.5 % increased by 16.36 %, 30.06 % and 46.01 %, respectively. The residual drift ratio decreased by 54.75 %, 61.61 %, and 52.98 % at 2.2 % drift ratio, respectively. Compared to CRC shear wall, the cumulative energy dissipation of the CSFRC shear wall with SFVFs of 0.75 % and 1.5 % increased by 39.54 % and 94.10 %; and the ductility increased by 5.12 % and 18.06 %, respectively. These improvements indicated that applying SFRC with SFVFs of 0.75 % and 1.5 % to shear walls reinforced with CFRP bars could effectively improve the seismic performance and compensate for the shortcomings of resilient shear walls. In addition, increasing the axial load ratio improved the bearing capacity, but decreased deformation capacity and accelerated stiffness degradation. An increase in concrete strength significantly improved the bearing capacity, stiffness and energy dissipation but reduced ductility. Meanwhile, the stability of lateral loads at large drift ratios weakened. Additionally, a detailed finite element model (FEM) was established using DIANA and the accuracy was verified by comparing the simulation and experimental results. Subsequently, parametric analyses were carried out to study the effects of shear span ratio, CFRP bar ratio, and wall thickness on the seismic behaviour of CSFRC shear walls.

Behavior of steel plate shear walls reinforced with stiffened FRP plates

Steel plate shear walls require retrofitting due to factors such as corrosion, long–term loading and functional changes. In an effort to modernise the technology used for strengthening and retrofitting steel plate shear walls, fibre–reinforced polymer (FRP) plates with additional stiffeners are employed to enhance the shear capacity of steel structures. In this study, the static properties of steel plates reinforced with these stiffened FRP plates were experimentally investigated. The application of this strengthening methodology substantially enhanced the out–of–plane stability, shear stiffness and bearing capacity of the plates, while also reducing fatigue damage. Equations for estimating the buckling and ultimate load of steel plates reinforced with stiffened FRP plates have been derived, enabling predictions of their practical performance. Finite element models incorporating the potential failure of epoxy at the FRP–steel interface were developed for further analysis. A numerical study was performed to investigate the optimal thickness of the FRP stiffener. The analysis revealed that stiffener thicknesses exceeding 6 mm did not significantly contribute to the enhancement of the load–bearing capacity or to the prevention of debonding. When the FRP rib thickness exceeds 6 mm, the economy was poor. The aforementioned findings are of considerable engineering importance, especially in the context of improving fatigue properties and shear load–bearing capacity of thin steel plates.

Cyclic Behavior of Partially Prefabricated Steel Shape-Reinforced Concrete Composite Shear Walls: Experiments and Finite Element Analysis

Due to the higher lateral stiffness, load-carrying, and energy dissipation capacities compared with traditional reinforced concrete (R.C.) shear walls, steel shape-reinforced concrete (SRC) shear walls, in which steel profiles are encased in the boundary elements, have been widely applied in high-rise buildings. In order to simplify the on-site construction procedure, this paper proposes a novel partially prefabricated steel shape-reinforced concrete (PPSRC) shear wall using throat connectors. Based on the pseudo-static tests of two large-scale specimens, the effect of construction methods (prefabricated or cast in place) on the cyclic behavior of PPSRC shear walls was investigated by the hysteretic loops, skeleton curves, stiffness degradation, energy dissipation, and deformation decomposition. The test results indicated that PPSRC shear walls could exhibit a comparative cyclic response with the cast-in-place SRC shear walls, and the proposed throat connectors could effectively transfer the stress of the longitudinal reinforcements. Finally, a macro-modeling of PPSRC shear walls based on the multi-layer shell elements in OpenSees 3.3.0 was established and validated by the test results, and the parametric analysis of the axial compression, steel ratio, and concrete strength of prefabricated and cast-in-place parts was then conducted.

Structural Performance of Ferrocement Hollow Shear Walls Subjected to Lateral and Compressive Axial Loads

In this study, ten shear walls were experimentally tested to examine behaviour of ferrocement hollow shear walls subjected to axial and lateral loads. Ferrocement mortar (FM) was used to build eight walls, while normal concrete (NC) was used to build two controls. Walls were lateral reinforced using conventional stirrups, two layers of welded wire mesh (WWM), and expanded steel mesh (ESM). Two specimens lacked lateral reinforcement except for one transverse web in the center of the inner hole. Two symmetric groups of five walls each were created by dividing the walls. While the other group was loaded laterally, one group was loaded axially. In each group, the load–displacement relationship, maximum load and associated displacement, stiffness, ductility, and failure mechanism of FM and NC walls were compared. The results showed that FM walls provided with ESM and WWM had ultimate axial loads that were, respectively, 36% and 19% higher than NC control walls. Ultimate lateral loads and related ultimate drifts of FM walls reinforced with two layers of WWM and ESM were, respectively, 68% and 39%, 96% and 43.5%, larger than control NC wall. For lateral loads greater than those applied to the NC control wall, stiffness increase ratios for FM walls ranged from 2.5% to 89.5%, and for axial loads, they ranged from 20% to 150.5%. The ductility of FM walls increased when compared to NC walls by 58.5% and 158.8% for axial and lateral loading, respectively, when two layers of WWM were utilized to lateral reinforce FM walls. When two layers of ESM were applied to laterally reinforce FM walls in comparison to an NC wall, this increased the walls' ductility under axial and lateral loads by 110.5% and 214.7%, respectively.

Cyclic behaviour of Glulam, LVL and GLVL shear walls and their base connections

This paper presents an experimental study aimed at characterizing the lateral cyclic behaviour of Glulam (GL), Laminated Veneer Lumber (LVL), and Glued Laminated Veneer Lumber (GLVL) shear walls anchored to the foundation by means of conventional hold downs and angle brackets, which are fastened to the timber walls with annular ring nails. Monotonic and cyclic tests are conducted on these mechanical anchors, with hold down connections tested under tensile loads and angle bracket connections under shear loads. Withdrawal tests on annular ring nails embedded in GL, LVL, and GLVL elements are also conducted, to investigate the withdrawal response of the fasteners. The experimental tests reveal that the lateral behaviour of GL, LVL, and GLVL shear walls is similar to that of Cross-Laminated Timber (CLT) shear walls, primarily governed by the wall base connections and by the wall geometry. Hold down and angle bracket connections exhibited a mechanical behaviour governed by the steel-to-timber joints, to large extent comparable with that of typical hold downs and angle brackets fastened to CLT elements. Generally, higher ductility and lower load carrying capacity were reached by hold downs and angle brackets fastened to GL elements compared to those reached by hold downs and angle brackets fastened to LVL and GLVL elements. All quantities relevant for the seismic design, such as stiffness, load carrying capacity, ductility, and overstrength factors are calculated and discussed through the paper. These quantities are then compared with results from different experimental investigations on hold downs and angle brackets fastened to CLT elements available in the literature. Finally, an analytical model for the calculation of the lateral load carrying capacity of the shear walls is presented and used to verify that the same calculation models used for CLT shear walls can be adopted for GL, LVL, and GLVL shear walls.

Study on the Shear Behaviors and Capacity of Double-Sided Concrete-Encased Composite Steel Plate Shear Walls by Experiment and Finite Element Analysis

Concrete-encased composite plate shear walls (C-PSW/CEs) can realize the in-plane shear yielding of infill steel plate with the buckling restrained from the concrete panel. Concrete panels also additionally resist portions of lateral loading in C-PSW/CEs, whereby the shear stiffness and strength of the C-PSW/CE are improved. However, research on the in-plane behaviors of concrete panels and the interactions between structural elements is limited. In this paper, the mechanical characteristics and the interactions and the shear resistances of C-PSW/CEs with double-sided concrete encasements were studied. First, the effects of concrete thickness on the damage process, steel plate buckling, and shear resistances of C-PSW/CEs under lateral loading were tested. Then, finite element analyses of the internal forces of the horizontal and inclined cross-sections and the shear force–drift ratio responses of C-PSW/CEs were undertaken with the extended finite element method (XFEM) to simulate the cracking behaviors of concrete panels. A shear force–drift ratio model based on mechanics was developed by considering the lateral load resistances of concrete panels and their effects on steel plates in C-PSW/CEs.

Strength calculation method and numerical simulation of slender concrete shear walls with CFRP grid-steel reinforcement

A series of experimental research has demonstrated superior hysteretic behavior, damage mitigation, and self-centering properties of concrete shear walls incorporating CFRP grid-steel reinforcement. Developing comprehensive theoretical and numerical models becomes crucial to assess the performance of these novel walls for structural design and application purposes. Based on the preliminary experimental investigation, a strength calculation method and numerical model for slender concrete shear walls with CFRP grid-steel reinforcement were proposed in this study. The calculation method provided a stable estimation for the loading capacity and ultimate compressive strain of edge concrete for the slender CFRP grid shear wall. The fracture strain of outermost longitudinal CFRP grid and ultimate compressive strain of edge concrete were suggested for design. The numerical model integrated hybrid reinforcements and utilized MVLEM to simulate the nonlinear hysteretic behavior of CFRP grid shear walls, effectively considering specimen failure mechanisms. The model can well capture the hysteretic behavior of the specimen, involving the peak loading, envelope curve, residual deformation, and stiffness degradation. Finally, the parametric analysis was conducted to further investigate the effects of axial compressive ratio and aspect ratio on shear walls with CFRP grid-steel reinforcement.

Out-of-plane interactive behavior and design of novel T-hooked buckling-restrained steel plate shear walls

To eliminate the use of a large number of connecting bolts for the cover panels in conventional buckling-restrained steel plate shear walls (BRSPSWs), T-hooked BRSPSW was proposed by using T-sectional stiffeners for restraining the out-of-plane deformation of the cover panels. With larger-sized flexural cover panels that provide confinement effects to the infilled steel plate, the out-of-plane interactive behavior between the infilled steel plate and each cover panel is greatly concerned for safe designs of the T-hooked BRSPSW. In this paper, a refined finite element (FE) model was established for evaluating the out-of-plane restraining effects in the T-hooked BRSPSW. The key parameters affecting the high-order buckling modes of the infilled steel plate were analyzed. The average spacing between adjacent buckling half-waves varied from 0.15 to 0.7 times the height of the steel sub-plate across common parameter ranges. Furthermore, a formula that estimates the total extrusion force produced by the buckled steel plate was corrected. By simplifying the cover panels into one-way flexural plates under uniform force, a flexural moment amplification coefficient in the range of 1.11 − 9.74 was defined to consider the difference between the actual strip-shaped interaction forces and the simplified model. Finally, a formula to calculate the bending moment of cover panels was proposed to safely design the T-hooked BRSPSWs.

Out-of-plane impact behavior and post-impact damage evaluation of GFRP bar-reinforced concrete shear walls in fire

Fiber-reinforced polymers (FRP) have been a prospective material in engineering. However, the attenuation of FRP bar-reinforced concrete members in fire is unclear. This paper studies the impact resistance of glass fiber-reinforced polymer bar-reinforced concrete (GFRP-RC) shear walls under high temperatures. Considering the impacts of strain rate enhancement and high temperature softening on GFRP bars and concrete, a numerical model with finite elements in three dimensions was created. To verify the model, three cases were simulated and compared with the test records, including the seismic performance of FRP-RC shear walls under axial compression, the seismic behavior of reinforced concrete (RC) shear walls under high temperatures, and RC shear walls' impact response. Based on the calibrated numerical model, the displacement, impact force, reaction force, failure mode, energy distribution, internal force and the residual shear bearing capacity of GFRP-RC shear wall subjected to impact under different fire times were analyzed. The influence of fire time on the failure mechanism of GFRP-RC shear walls was studied. Taking the mid-span displacement as the damage index, the evaluation criteria for the four damage levels were determined. The findings indicate that the type of reinforcement has little effect on the shape of impact force, reaction force and displacement time history curve. The peak values of impact force and reaction force of RC walls are larger than those of GFRP-RC shear walls, while the former has smaller peak displacements and residual displacements. The damage of shear walls becomes more severe as the fire time increases, as does the displacement. Also, the impact force, reaction force, shear force and bending moment decrease gradually. The energy absorbed by shear walls is primarily dissipated by concrete, the part by GFRP bars accounting for a small proportion. The post-impact residual bearing capacity of GFRP-RC shear walls is linearly related to the mid-span displacement under impact loads, primarily influenced by high-temperature exposure.

Design & Analysis of Non-Linear Property of Material for Semi-Rigit, Fixed & Flexible Structural Frames

During an earthquake, failure of structure starts off-evolved at factors of weak spot. This weak point arises due to discontinuity in mass, stiffness and geometry of structure. The systems having this discontinuity are termed as irregular systems. Irregular structures contribute a massive portion of city infrastructure. The effect of vertically irregularities within the seismic overall performance of systems will become definitely vital. The main objective of the analysis is to study the behavior of flat slab system in vertical irregular multi-storied building against different forces acting on it during earthquake. Also, the objective of analysis is to study the structural behavior of shear wall – flat slab interaction with opening. The analysis is made between in the three types of G+9 storey building with 0 % vertical irregularity, 200 % vertical irregularity and 300% vertical irregularity. In all these building’s shear wall is provided with & without 20% opening. Total 15 modeled are studied and their results were compared. Key Words: Flat slab, Vertical Geometric Irregularity, Shear wall with opening, Response Spectrum analysis, STAAD Pro2007

Torsional behavior of composite shear walls and load‐bearing sandwich panels: An experimental investigation

Torsional behavior of composite shear walls and load‐bearing sandwich panels: An experimental investigation

Fire behavior of full-scale cold-formed steel center-sheathed shear walls under combined loads

An innovative cold-formed steel center-sheathed shear walls (CFSCSSWs) was proposed in this paper to improve the horizontal load-carrying capacity of conventional cold-formed steel walls. However, the fire behavior of this wall configuration was particularly worthy of attention because it was designed to be used in multi-story buildings, and there is still a lack of in-depth exploration of the fire performance and high-temperature horizontal load-bearing capacity of CFSCSSWs under combined loads. In this study, a compression test was first carried out to obtain the vertical load-carrying capacity of a full-scale CFSCSSW, followed by a fire test on a similar CFSCSSW subjected to combined vertical and horizontal loads to investigate the fire behavior of walls. Then, a finite element model was established and validated by test results to investigate the influence of various critical factors, including vertical and horizontal load ratios, height-width ratio, and sheathing thickness, on the fire behavior of the CFSCSSW. The results showed that the vertical load ratio presented a larger influence on the fire behavior of CFSCSSWs compared to the horizontal load ratio. The increasing aspect ratio can slightly improve the fire resistance of the wall under the same load ratio. The wall with a 0.8 mm thick sheathing exhibits better fire behavior under the same load ratio. A high-temperature horizontal load-carrying capacity calculation method for CFSCSSWs was proposed, and its good accuracy was found.

Lateral behavior of wood frame shear wall using PVC wood-plastic composite (WPC) veneer panels

With the growing awareness of environmental protection and green ecology, there has been significant attention on the utilization of new energy-saving and environmentally friendly materials in building structures. This article proposes a novel structure for PVC wood-plastic composite wall panels. The structure comprises Polyvinyl Chloride (PVC) wood-plastic composite materials as the facing panel and SPF (Spruce-Pine-Fir) dimensional lumber as the wall framework, connected using self-tapping screws. In this study, two standard composite wall panel specimens were subjected to testing using both monotonic loading and low-cycle reciprocating loading methods. Finite element models of the composite wall panels were created using ANSYS Workbench software for analysis, investigating the lateral performance of PVC wood-plastic composite wall panels. The analysis results indicate that PVC wood-plastic composite wall panels exhibit favorable shear strength, elastic lateral stiffness, and lateral deformation as shear walls. The shear wall model can be accurately represented in finite element software, with minimal discrepancy between experimental and finite element analysis results. Consequently, the utilization of PVC wood-plastic composite wall panels as shear walls holds promise for future applications in the structural field.

Effect of nano-SiO2 modification on the seismic performance of recycled aggregate concrete shear walls

Nano-silicon dioxide (nano-SiO2) can strengthen recycled aggregates and interface transition zones (ITZs), thereby improving the properties of recycled concrete structures. This study adopted nano-SiO2 modifications to improve the seismic behavior of recycled concrete shear walls. Quasi-static tests of one natural aggregate concrete shear wall and four concrete shear walls with different replacement ratios (30%, 50%, 70%, and 100%) of nano-SiO2 modified recycled aggregate (NSMRA) were conducted. The ductility factor, energy dissipation, lateral displacement components, stiffness, and strength degradation of NSMRA concrete (NSMRAC) shear walls were evaluated. The replacement ratio effects of NSMRA on the seismic behavior of shear walls were analyzed. It was determined that the NSMRAC shear walls exhibited higher ductility factor compared to recycled aggregate concrete (RAC) shear walls with similar conditions. The seismic behavior of the shear walls degraded as the replacement ratio of NSMRA increased. Based on the comprehensive evaluation of failure patterns and seismic performance indexes, the replacement ratio of NSMRA is suggested to be taken as 50% in the concrete shear walls. Finally, based on the summary of experiments and studies on the seismic behavior of RAC shear walls with shear failure, the applicability of existing formulae was evaluated by calculating the shear capacity of RAC shear walls, and the effect of nano-SiO2 modifications on the shear capacity of recycled concrete shear walls was analyzed.

Experimental and numerical study on seismic behavior of precast shear walls assembled with a socket vertical joint

In the development of precast shear wall structures, reliable and efficient connections of precast units are crucial for their seismic behavior. Meanwhile, the heavy precast units using conventional concrete bring a low lifting efficiency. Considering these issues, the paper proposed a novel type of socket vertical joint for precast shear walls made of steel fiber reinforced lightweight aggregate concrete (SFRLAC). Sixteen socket connection specimens, with four socket depths (100 mm, 150 mm, 200 mm, and 250 mm) and two interface treatments (smooth and exposed aggregate), underwent interface bonding performance tests using uniaxial tensile testing and finite element (FE) numerical models to determine the appropriate socket depth. Three specimens were tested using the low-cyclic loading test, including two reinforced SFRLAC precast shear walls assembled with a socket vertical joint and a cast-in-place reinforced SFRLAC shear wall as a reference. The failure patterns and process of the shear walls were observed, while the load-displacement curves were obtained. Additionally, a parametric analysis of different influencing factors was conducted using finite element (FE) numerical models. This analysis studied the bearing capacity, energy dissipation capability, deformation ability, and stiffness degradation of the shear walls. Results indicate that when the precast shear walls were damaged, the socket vertical joint was integrity and failed in bending-shear. The three specimens exhibited fewer differences in seismic behavior with relatively full hysteretic curves. The seismic mechanisms of the shear wall assembled with a socket vertical joint were elucidated by analyzing the numerical distribution of stress in both SFRLAC and steel bars at different stress levels. Furthermore, an expansion analysis was conducted to assess the impact of axial load ratios and shear to span ratios on the seismic behavior of precast shear walls.

Seismic behavior of horizontally spliced single-side superposed shear wall using a concealed column

The single-side superposed (SSS) shear wall is an innovative precast concrete sandwich panel that better meets the requirements of building industrialization. However, the seismic behavior of SSS shear walls remains inadequately understood. In this paper, a full-scaled horizontally spliced SSS shear wall using a concealed column and an integral SSS shear wall of the same dimensions were tested. The seismic behavior was investigated considering various aspects including hysteresis performance, bearing capacity, ductility performance, energy dissipation capacity, and stiffness degradation curve. The simulation models were established by the Abaqus, which provided the verification and further research for the test. Furthermore, two innovative splicing forms were proposed to optimize the existing specimens through the Abaqus. The experimental results indicated that implementing the vertical joint would lead to a decrease in the yield-bearing capacity by 24%, but it would also enhance the ultimate bearing capacity by 12.7%. Meanwhile, the deformation capacity would improve by 9.7%. The numerical simulations demonstrated that the suggested splicing methods effectively meet the demands of building industrialization.

Evaluating Seismic Performance in Reinforced Concrete Buildings with Complex Shear Walls: A Focus on a Residential Case in Chile

This study employs a non-linear static analysis, known as pushover analysis, to explore the flexural-compressive behavior of complex shear walls within a reinforced concrete (R.C.) structure, adhering to contemporary design standards in Chile. The primary objective is to assess the initiation of damage as the building approaches the limit states outlined in Achisina’s seminal “Performance Based Seismic Design” framework. To achieve this, a sophisticated fiber model, accounting for the confined behavior of concrete derived from the structural elements’ detailing, has been uniformly integrated across the building’s entire height. Furthermore, the analysis incorporates a rigid diaphragm to simulate the R.C. slab’s response accurately. The study implements the N2 method, adjusting for seismic demands in an acceleration-displacement format, which leverages the displacement spectrum defined by Supreme Decree 61, a legislative response to the 8.8 Mw Maule earthquake in 2010. The findings reveal that the analyzed structure meets the immediate occupancy performance level with drifts nearing 5‰ in the symmetrical Y direction. This outcome aligns with prior assessments of Chilean R.C. wall buildings. However, in the asymmetric X direction, the structure exhibits a higher degree of structural damage, aligning with a life safety performance level. This differentiation underscores the critical need for nuanced understanding and modeling of structural behavior under seismic loads, contributing to the ongoing refinement of seismic design practices and standards.

Lateral hysteretic behavior of precast concrete shear walls with unjointed vertical distribution bars and opening

Precast concrete shear walls with unjointed vertical distribution bars have desirable lateral resistance compared with cast in situ concrete shear walls and much less construction cost as no sleeve splicing joint is needed. However, the influence of opening in the precast panels on their lateral hysteretic behavior has not been fully investigated. This study presents the results of cyclic loading tests of three full size precast concrete shear walls with unjointed vertical bars and opening. The test results showed that these shear walls had similar failure modes as a cast in situ concrete shear wall, such as cracking in the corners of the opening and the concrete and steel bars crushing at the bottom corners of the shear walls. The peak load of the positive and negative loading cycles and the stiffness of the unjointed shear wall with a window opening were 14.6%, 4.3% and 1.3%, respectively, smaller and the ductility ratio was 37.6% higher, than an otherwise the same cast in situ shear wall. The lateral stiffness of the unjointed shear wall with a door opening was 35% smaller than that of the one with a window opening, due to the stiffness contribution of the wall segment underneath the window opening. The development of the longitudinal strains of concrete and steel strain along the height of the wall limbs generally met the plane section assumption. However, those next to the vertical joint interface were affected by the development length of the shear force after the bedding mortar cracked under tension. The determination of the development length needs to consider the influence of the stiffness of the link beam and the wall segment underneath the opening.

Seismic behavior of resilient composite steel plate shear wall using experimental investigations

Using composite encased steel plate shear wall (C-SPSW) has been attractively raised for enhancing the lateral seismic performance and increasing the useful floor area. Although, the experimental investigations have proved excellent dynamic behavior of C-SPSWs, structural damage as well as residual displacements are the main disadvantages of C-SPSWs, which are not consistent with low damage design (LDD) approaches. In the current study, the C-SPSWs performance is improved using the self-centering (SC) technique to control the both structural damage and reduce residual displacements as well. Five tests on C-SPSWs including three SC composite encased steel plate shear walls (SC-C-SPSWs) were conducted under gravity and lateral cyclic loads. The SC-C-SPSW consists of C-SPSW equipped with unbonded posttensioned tendons (UPT) to have resilience ability. For this aim, two symmetrical gaps were provided at the ends of the wall, and the UPTs were mounted at the wall ends and crossed into the foundation through the middle of the gaps. Under lateral load, the gap opening allows the elongation of UPTs that induce a high restoring forces, forcing the wall to have rocking movement above the foundation. In comparison with C-SPSWs, the SC-C-SPSWs exhibited low damages, higher shear strength capacity between 28% and 35%, larger ultimate drift capacity and more displacement ductility as 45–136% in average. Furthermore, the SC ability and the UPTs restoring forces effectively reduced the residual drift and the SC moment causes the recovery of the residual drift between 90% and 105%. Moreover, compared to C-SPSWs, the residual lateral strength of SC-C-SPSWs was improved by 30% in average.