Coupled Shear Walls Research Articles

Experimental and numerical studies on seismic performance of a novel lead viscoelastic coupling beam

Replaceable coupling beams (RCBs) with different types of dampers have gained significant attention in coupled shear walls for enhancing seismic performances in high-rise buildings, showing superior advantages to conventional reinforced concrete coupling beams (RCCBs). Recently, the authors proposed the hybrid lead viscoelastic damper (HLVD), and its basic mechanical behaviors were experimentally studied. This paper used the HLVD as a replaceable fuse and installed it in the coupling beam to form a new RCB, i.e., lead viscoelastic coupling beam (LVCB). To examine the seismic performance of the LVCB, experimental and numerical studies were carried out in the present study. Quasi-static tests were conducted to comparatively investigate the seismic performances of the RCCB and LVCB. The experimental findings revealed that the RCCB experienced shear failure with severe pinching behaviors under cyclic loadings, while the LVCB exhibited a resilient behavior, showing favorable energy dissipation capacity with a ductile deformation capacity exceeding a rotation angle of 0.04 rad. The LVCB also demonstrated excellent recoverability in repeatability tests, proving its merit for maintaining post-earthquake functionality. Numerical simulations indicated that adjusting the lead rods of the LVCB could conveniently enhance the load-carrying capacity and energy dissipation capacity of the LVCB. The isolated floor slab was recommended as a low-damage control solution for the LVCB to facilitate post-earthquake replacement.

Experimental study to unraveling the seismic behavior of CFRP retrofitting composite coupled shear walls for enhanced resilience

This study focuses on the empirical examination of the nonlinear seismic performance of carbon fiber-reinforced polymer (CFRP)-strengthened composite coupled reinforced concrete (RC) shear walls. The experimental setup involves testing the structure in two distinct states, wherein CFRP sheets are utilized for retrofitting and reinforcement. In the initial phase, three samples undergo reinforcement utilizing distinct patterns of CFRP sheets. In the subsequent stage, an additional trio of specimens is fabricated and tested without the application of CFRP sheets. Subsequently, all structures are exposed to a load equivalent to 60 % of their flexural capacity. Following this, the tested specimens undergo retrofitting with CFRP sheets, utilizing the same patterns as in the initial phase. The retrofitted composite coupled shear walls are then subjected to retesting. The principal aim of CFRP retrofitting is to amplify the flexural and shear capacities of the specimens, empowering them to endure heightened seismic loads in comparison to their original configurations. This research contributes by evaluating ductility, ultimate strength, energy dissipation, and construction costs associated with composite coupled steel plate-concrete shear walls. All specimens underwent cyclic loading in accordance with the ATC-24 guidelines [1], which provide standard protocols for testing the cyclic performance of structural components. These guidelines, outline procedures for simulating seismic loading conditions in laboratory settings to evaluate the performance of structural systems under cyclic loading. Finally, a parametric study explores the impact of CFRP sheets and their adhesion patterns on the seismic behavior of composite coupled shear walls. The selection of the optimal retrofitting scheme considers the construction cost of each specimen based on the total area of CFRP sheets utilized.

Seismic flexural rehabilitation of RC coupling beams with FRP sheets: Evaluation of EBROG technique

Coupled shear walls (CSW) in reinforced concrete (RC) structures must be connected with stiff and strong coupling beams (CBs) to perform effectively during an earthquake. However, many RC buildings with CSW resisting systems have been designed and constructed with insufficient seismic requirements based on old codes and standards. During major earthquakes, these systems respond unsatisfactorily and may prematurely collapse. Strengthening of different RC members including CBs with fiber-reinforced polymer (FRP) sheets attached through externally-bonded reinforcement (EBR), though attractive, has always suffered from premature debonding of FRP from concrete substrate. The alternative externally-bonded reinforcement on grooves (EBROG) technique has been shown to overcome premature debonding when used instead of the EBR method. Therefore, this experimental study investigated the efficiency of rehabilitation with carbon FRP (CFRP) through the EBROG technique on the seismic behavior of flexural-deficient RC coupling beams. Furthermore, different patterns of flexural retrofit, as well as the effectiveness of FRP fans, have been studied to prevent undesirable debonding of CFRP strips. Four large-scale RC coupling beams have been identically constructed. The CB specimens were reinforced in such a way as to be flexural deficient, i.e., their loading capacities in shear were much more than that in bending. The CB specimens were then retrofitted with CFRP sheets in different patterns. The maximum peak loads of specimens CBF-1 L, CBF-1 L.F, and CBF-2 L.F increased by 37.0 %, 44.3 %, and 46.0 % over the control, respectively. Upon comparing the loading capacities of specimens CBF-1 L and CBF-1 L.F, it was found that FRP sheets installed through the EBROG method could delay premature debonding and utilize approximately 80 % of the CFRP's capacity. It was observed that using the EBROG technique and FRP fans at the termination point of FRP sheets, fully eliminated the debonding, and the full capacity of the CFRP sheets was utilized accompanied by their rupture, with improved ductility and increased load-carrying capacity of up to 46 %. It was also found that CFRP composites attached to concrete through the EBROG method significantly increased the strength, stiffness, ductility, and energy dissipation of CB specimens in terms of seismic rehabilitation.

Subduction and Shallow Earthquake Demand on Coupled Composite Plate Shear Wall–Concrete-Filled System

Subduction and Shallow Earthquake Demand on Coupled Composite Plate Shear Wall–Concrete-Filled System

Optimality of reinforced concrete coupled shear walls using machine learning

Optimality of reinforced concrete coupled shear walls using machine learning

Seismic performance analysis and control method of composite coupled shear wall with steel plate-fiber reinforced concrete coupling beams

This paper based on the study of steel plate-fiber reinforced concrete coupling beam components, designs a basic model of composite coupled shear walls with steel plate-fiber reinforced concrete coupling beams. The seismic performance of this model was numerically simulated using the ABAQUS finite element software, analyzing the stress distribution of various parts and the development pattern of plastic hinges in the structure. It also examines how factors such as axial compression ratio, coupling beam cross-sectional dimensions, single-sided wall limb aspect ratio, and total floor height affect the seismic performance of this type of coupled shear wall, providing a reasonable range for axial compression ratios and coupling ratios for composite coupled shear walls with steel plate-fiber reinforced concrete coupling beams. Based on the obtained reasonable axial compression ratio and coupling ratio, and using the analytical solution of the continuum method, a method for controlling the seismic performance of coupled shear wall structures was proposed. Results show that the composite coupled shear walls with steel plate-fiber reinforced concrete coupling beams exhibit high load-bearing capacity and lateral stiffness under inverted triangular horizontal loads, with good displacement ductility and strong energy dissipation capability, making it an excellent seismic performance coupled shear wall system. As the axial compression ratio increases, the displacement corresponding to the yield point and peak point of the structure gradually decreases, and the displacement ductility coefficient shows a trend of first increasing and then decreasing; it is recommended that when designing steel plate-fiber reinforced concrete coupling beam-coupled shear walls, the axial compression ratio should not exceed 0.3. Numerical analysis of coupling ratio-related parameters indicates that in high-intensity seismic design areas, the range of coupling ratios should be between 45% and 60%.

Seismic performance evaluation of hybrid coupled shear wall system with shear and flexural fuse-type steel coupling beams

Seismic performance evaluation of hybrid coupled shear wall system with shear and flexural fuse-type steel coupling beams

Experimental and numerical studies on the seismic performance of fully cast‐in‐situ concrete exterior walls

AbstractTo investigate differences in the seismic performance of the main structure between a window sill wall and a coupling beam under two different flexible connections, two coupled shear wall specimens with concrete window sill walls and one counterpart specimen without infill walls (S‐1) were designed for quasistatic tests. The test results indicated the following: In specimen S‐2, fully disconnected by polyvinyl chloride (PVC) tubes, the coupling beam and window sill wall formed a double coupling beam working mode. The failure mode of the main structure of specimens S‐1 and S‐2 was the beam‐hinge mechanism. In specimen S‐3, which was partially disconnected by extruded polystyrene board strips, the coupling beam and the window sill wall worked together as an integral beam and underwent shear failure, revealing significant differences in failure mode compared to S‐1. In addition, the relative deformation between the first‐floor window wall and the main structure of specimen S‐2 could occur, and the interaction between the two was relatively small compared with that of specimen S‐3. Similarly, compared with those of specimen S‐1, the peak loads of specimens S‐2 and S‐3 were approximately 52.37% and 79.99% greater, respectively. The ductility coefficient of S‐2 was equivalent to that of S‐1, while the displacement ductility coefficient of S‐3 decreased by approximately 41.95% compared to that of S‐1. The connection between the main structure and the concrete infill wall with PVC effectively reduced the interaction between the two components and reduced the damage. Finally, MSC. Marc software was used to establish a solid model and simplified model of the equivalent compression bars of all the specimens, and the results were compared with the test results.

Mechanical behavior of ECC-reinforced coupled shear wall

PurposeBased on the weak seismic performance and low ductility of coupled shear walls, engineered cementitious composites (ECC) is utilized to strengthen it to solve the deformation problem in tall buildings more effectively and study its mechanical properties more deeply.Design/methodology/approachThe properties of reinforced concrete coupled shear wall (RCCSW) and reinforced ECC coupled shear wall (RECSW) have been studied by numerical simulation, which is in good agreement with the experimental results. The reliability of the finite element model is verified. On this basis, a detailed parameter study is carried out, including the strength and reinforcement ratio of longitudinal rebar, the placement height of ECC in the wall limb and the position of ECC connecting beams. The study indexes include failure mode and the skeleton curve.FindingsThe results suggest that the bearing capacity of RECSW is significantly affected by the ratio of longitudinal rebar. When the ratio of longitudinal rebar increases from 0.47% to 3.35%, the bearing capacity of RECSW increases from 250 kN to 303 kN, an increase of 21%. The strength of longitudinal rebar has little influence on the bearing capacity of RECSW. When the strength of the longitudinal rebar increases, the bearing capacity of RECSW increases little. The failure mode of RECSW can be improved by lowering the casting height of the ECC beam in a certain range.Originality/valueIn this paper, ECC is used to strengthen the coupled shear wall, and the accuracy of the finite element model is verified from the failure mode and skeleton curve. On this basis, the casting height of the ECC casting wall limb, the strength and reinforcement ratio of longitudinal rebar and the position of the ECC beam are studied in detail.

Research on Optimization Design of Prefabricated ECC/RC Composite Coupled Shear Walls Based on Seismic Energy Dissipation

This study explores an advanced prefabricated composite structure, namely ECC/RC composite shear walls with enhanced seismic performance. This performance enhancement is attributed to the strategic use of engineered cementitious composites (ECC) known for their superior ductility. The study conducts both experimental and numerical simulation analyses to scrutinize the seismic energy absorption capabilities of this innovative structure. Emphasis is placed on critical aspects, such as the optimal deployment areas for ECC within composite coupling beams and shear walls, the grade of ECC strength, the proportion of stirrups in coupling beams, and the caliber of longitudinal reinforcement. Through finite element analysis, this research quantitatively assesses the impact of these variables on seismic energy dissipation, incorporating evaluations of load–displacement hysteretic behaviors and the energy dissipation potential of ECC/RC shear wall samples. The findings suggest the optimal ECC application in the coupling beams, and within a 14% structural height at the base of shear walls. Recommended design parameters include an ECC strength grade of E40 (40 MPa), longitudinal reinforcement of HRB400 (400 MPa), and a stirrup ratio in coupling beams of 0.5%.

SEISMIC ANALYSIS OF MULTISTORIED OPEN GROUND STORY BUILDING WITH DIAGONAL STRUT AND SHEAR WALLS

The Open Ground Story (OGS) building is a functional need of all urban areas so cannot be eliminated. According to studies from previous earthquakes, when there is severe earthquake shaking, Reinforced Concrete (RC) frame buildings with open ground levels function badly. In this work, four models of G+14 RC frame buildings with and without a shear wall, coupled sheal wall, and diagonal strut were modeled and analyzed using ETABS-2018 software's static and dynamic response spectrum method. Model 1 open ground story RC building without strut and the shear wall was compared to the other three models that included a shear wall, coupled shear wall, and diagonal strut. As a result of the findings, it has been determined that shear wall, coupled shear wall, and diagonal strut not only increased the stiffness but also reduced displacement. A model with a combination of shear wall and coupled shear wall showed a minimum base shear and overturning moment than all other models.

Numerical study on optimized application of engineered cementitious composites in RC coupled shear wall structures

Due to the superior tensile strain-hardening and multi-cracking properties, engineered cementitious composites (ECC) can be adopted in reinforced concrete (RC) shear walls and coupling beams to improve the seismic performance and damage tolerance with simplified reinforcement details. This study numerically investigates the optimized application of ECC in coupled RC shear wall structures based on refined two-dimensional finite element models incorporating constitutive models of ECC and concrete for nonlinear shear behaviors. The balance between cost and performance is adequately considered from the material, member, and structural levels. At the material level, the reasonable tensile properties of ECC are suggested based on the parametric analysis of coupling beam and shear wall specimens. At the member level, the effect of diagonal bar ratios on the seismic performance of coupled walls is investigated to propose reasonable diagonal bar ratio of ECC coupling beams. Finally, at the structural level, nonlinear dynamic time-history analysis of a typical 11-story coupled wall structure based on practical engineering is conducted to investigate the influence of the application ranges of ECC on the seismic performance of the wall system. The damage indexes, including story curvature and crack width, are analyzed and compared. Based on the analytical results, recommendations related to some key issues on the application of ECC in traditional RC structures are provided, including the application range and tensile properties of ECC, as well as the reinforcement details.

Shaking table tests and numerical analysis of RC coupled shear wall structure with hybrid replaceable coupling beams

AbstractA variety of innovative structural solutions have been recently introduced to mitigate damage and expedite the repair of buildings subjected to extreme seismic events, hence contributing to the urgent need for resilient societies. In this context, the present study experimentally and numerically investigates an innovative reinforced concrete (RC) shear wall (SW) structure with replaceable coupling beams (CBs) equipped with hybrid devices. These hybrid devices couple metallic and viscoelastic dampers and aim at satisfying multiple lateral load performances effectively. To assess the seismic performance of the proposed coupled SW system and verify the design principle, comparative shaking table tests were performed on two 1/4‐scale seven‐story SW structure specimens, including a conventional RC coupled SW and the proposed coupled SW with hybrid devices. The tests results indicate the improved performance of the proposed compared with the conventional system in terms of: (1) reduced interstory drifts and story accelerations demand under a wide range of seismic intensities, (2) concentrated damage in the hybrid device and minimal damage to the other components contributing to the reparability of the structure. Furthermore, 3D finite element models for the shaking table test specimens were established in OpenSees and validated against experimental response. Successively, a numerical parametric study was conducted by performing non‐linear response history analyses under a set of 22 ground motions to investigate the influence of different design configurations of the hybrid device on the peak interstory drifts and peak story accelerations.

Bidirectional seismic performance and design approach of RC infill wall with PVC tubes

In some regions, masonry infill walls are replaced by cast-in-situ reinforced concrete (RC) infill walls to effectively solve problems such as leakage, long construction periods, and high out-of-plane vulnerabilities. However, these high-stiffness RC infills impose excessively high constraints on the adjacent structural components, leading to disadvantageous seismic responses. Therefore, a flexible connection is required to isolate the infill walls and main structures. However, flexibly connected RC infill walls are not widely used in practical engineering because they are weakly supported by relevant standards and codes and have an insufficient calculation basis, especially for evaluating out-of-plane seismic properties. This study considers a type of RC infill wall with a common layout of polyvinyl chloride (PVC) tubes for coupled shear wall systems. The in-plane and out-of-plane seismic performances of the system are studied using quasi-static loading tests and finite element analysis, respectively. The system exhibits satisfactory seismic properties during the test because the PVC tubes provide effective flexible isolation. Out-of-plane pushover analysis and bidirectional loading are successively simulated with different parameters to study the out-of-plane reliability of the infill walls with and without openings. Finally, a seismic design approach for such infill walls, considering both in-plane and out-of-plane resistances, is proposed and validated using novel and concise design formulas. The accuracy of the design approach is verified using finite element calculations.

Experimental and numerical evaluation of seismic behavior of coupled walls connected by post-tensioned, unbonded, precast concrete coupling beams

To investigate the seismic performance of coupled shear walls, which are connected by post-tensioned, unbonded, precast concrete coupling beams (PCCB), two 1/7-scale experiments with 8-story coupled shear walls under cyclic lateral loadings were conducted. Coupling of concrete shear walls is achieved by post-tensioning concrete beams to the wall piers using unbonded post-tensioning tendons (UPT) at the floor and roof levels. Experimental results show that little damage occurs in the coupling beams and the wall regions when the specimen undergoes large nonlinear displacements. The residual displacements of the specimen are small because of the restoring effect of the post-tensioning force. The seismic performance of three systems including CW-RC (coupled wall systems that use traditional RC coupling beams), CW-UP (coupled wall systems which use only post-tensioning tendons without steel reinforcement through the beam-wall joints), and CW-HUP (shear walls and PCCB that use combinations of steel reinforcement and post-tensioning tendons) are evaluated by means of nonlinear dynamic analysis. The calculation results indicate that the inter-story drift and peak lateral displacements of CW-HUP and CW-UP are greater than that of CW-RC, whereas the residual deformations are reduced because of the self-centering effect of the post-tensioning tendons.

Seismic Design and Performance of Composite Coupling Beam-to-SpeedCore Wall Connections

Coupled composite plate shear walls—concrete filled (CC-PSW/CFs) are an effective seismic lateral-force-resisting system for the design and construction of mid- to high-rise buildings around the world. The coupled system consists of two or more composite plate shear walls—concrete filled (C-PSW/CFs) connected to each other using composite coupling beams located at the story heights. The CC-PSW/CF system can provide higher overturning moment capacity, lateral stiffness, and ductility than uncoupled walls. Concrete-filled steel box sections are typically used for the composite coupling beams, which are designed to be flexure critical members. When the CC-PSW/CF system is subjected to lateral seismic forces, plastic hinge formation and inelastic deformations (energy dissipation) occur near the ends of most of coupling beams along the structure’s height, followed by flexural hinging of the C-PSW/CFs, typically at the base. This paper presents the details and design of four composite coupling beam-to-C-PSW/CF connection configurations. Six connection specimens representing the four connection configurations, with beam clear span-to-section depth, Lb/d, ratios of 3.5 and 5.1, were designed and tested. The lateral force-displacement and moment-rotation responses of the specimens are summarized. All six composite coupling beam-to-C-PSW/CF wall connection specimens (1) developed and exceeded the plastic flexural capacities, Mp, of the coupling beams calculated using the plastic stress distribution method and (2) developed chord rotation capacities greater than 0.03 radian before their flexural strength degraded to 80% of the plastic moment capacity, Mp.

Damage tracking and hysteresis‐based evaluation of seismic‐excited RC shear wall using monitoring data

SummaryReinforced concrete (RC) shear walls play an important role as the seismic resisting system in tall buildings. Yet, assessing the seismic damage of real‐world shear walls remains a challenging task. In this study, a damage index that relies on the vibration data measured by the sensors embedded in the structure is proposed to evaluate the damage condition of shear walls. The damage index is formed by the linear combination of two normalized terms, which, respectively, characterize the peak and the cumulative damages of the shear walls with little knowledge of real‐life structural hysteresis. The damage tracking and evaluation based on the substructure level and the story level are discussed. The damage indices evaluated using the hysteretic loops made by the shear and bending information of the shear wall are further compared. The feasibility of the proposed damage index is examined using a numerically simulated 12‐story coupled shear wall structure. It is then applied to analyze the experiments regarding the damage condition of RC shear walls under earthquakes. Results show that the proposed damage index can track the damage states of RC shear walls under seismic excitations. Analysis suggests that the proposed damage index could trace and distinguish the progression of shear and flexural damages, which potentially supports the post‐earthquake structural safety management.

Analysis of Multi-Storied Buildings with the Use of Coupled Shear Walls

The present study focuses on the use of coupled shear walls with and without dampers for resisting seismic loads. Multistory structures with and without shear walls are analysed. Different parameters, such as the structure's base shear, storey drift, storey displacement, storey stiffness, and storey shear, are evaluated, and a comparative study is performed. It is observed that coupled shear walls with fluid viscous dampers reduce storey drift by 24% and storey displacement by 45% when compared to buildings without shear walls. A coupled shear wall with a damper has a 29% higher stiffness than a coupled shear wall without a damper, thus performing effectively in resisting lateral forces induced by an earthquake.

Seismic performance of coupled shear walls with novel hybrid construction methods under high axial loading

In this paper, two novel hybrid construction methods were proposed for coupled beam shear walls with both prefabricated and cast-in-place (CIP) components in order to control the construction quality, reduce environmental impact and accelerate the construction speed for high-rise buildings. The first one was designated as a composite wall, which consisted of an inner prefabricated frame wall and an outer post-cast frame wall. The second one was a post-cast beam coupled wall, which was made of double prefabricated wall legs and a CIP coupling beam. A full-scale experiment was then designed to test five specimens of identical geometrical dimensions and structural details under a constant high axial load ratio of 0.5 and cyclic loads to evaluate the seismic performance. They were one CIP, two identical composite walls, and two identical post-cast beam coupled walls. The results indicate that: (1) the proposed hybrid prefabricated shear walls had almost similar flexural failure modes and cracking distribution with the CIP wall; (2) both proposed walls had comparable seismic performance with the CIP wall in terms of lateral load capacity, deformability and ductility; (3) the proposed composite walls had significantly larger energy dissipation capacity than the CIP wall; (4) the identical walls of the same construction method had similar performance, indicating a stable performance of the proposed walls; (5) under the high axial loading, the ductility of the proposed walls had a good ductility in the range of 3.25–3.83. Overall, the proposed walls have a satisfactory seismic performance and hence can be taken as an alternative for the conventional CIP coupled shear walls in practice for high-rise buildings.

Experimental and numerical studies on open-close gap damper for self-centering prefabricated coupled shear wall

An open-close gap damper (OCGD) for self-centering prefabricated coupled shear walls was proposed, which could adapt to large deformations near the joints and help the structure achieve both self-centering and energy dissipation capacity. Static tests and numerical simulations were used to obtain the hysteretic curve of the damper, which verified its energy dissipation capacity. Through simulation, it was found that the proposed damper greatly improved the energy dissipation capacity of the structure without reducing its original self-centering ability. Finally, the relationship between the hysteretic performance and design parameters of the proposed damper was obtained through theoretical analysis, which provided a reliable basis for the design of open-close gap damper.