Coupled Shear Wall Structures Research Articles

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%.

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.

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.

A unified section-based restoring force model for reinforced concrete coupling beams based on the XGBoost model: Establishment, validation and application

To enhance the seismic performance of reinforced concrete (RC) coupling beams, improved reinforcement details such as diagonal layout and high-performance concrete including fiber reinforced concrete (FRC) as well as engineered cementitious composites (ECC) are widely investigated and applied. Despite the numerous experimental studies on various reinforced concrete coupling beams, there is still a lack of unified, efficient and accurate numerical model applicable to all kinds of concrete and reinforcement layouts, leading to difficulty in numerical study and proper design of coupling beams and coupled shear walls. In this study, a database containing 180 reinforced concrete coupling beam specimens is first set up. Then the key mechanical indexes of test curves including the peak load, peak beam rotation, yielding beam rotation and softening beam rotation are predicted using the trained XGBoost models. The feature importance and partial dependence of different independent variables are analyzed. Based on the predicted results, the skeleton curves of the section-based restoring force model can be obtained. Besides, a new hysteretic rule for the restoring force model which can account for the pinching effect, strength and stiffness degradation is proposed. The proposed model is then implemented in ABAQUS 2017 software, of which the accuracy and applicability are validated by twelve coupling beam specimens with different concrete materials and reinforcement layouts. Finally, a coupled shear wall specimen is simulated to quantitatively and thoroughly evaluate the effects of key indexes of the coupling beams on the seismic performance of the coupled shear wall structures.

An Efficient Model for the Coupling Beam Using Damping Devices in Coupled Shear Wall Structures under Earthquake Loads

This paper proposes a new element for modeling the energy-dissipation coupling beam to analyze the coupled shear wall structure under seismic loading. The new beam element includes 2 rigid beams and an energy dissipation device in the middle. The element stiffness matrix is derived based on principles of nonlinear mechanics. A procedure of the incremental-iterative solution is built using the Newmark method and adopted for solving the nonlinear equation of motion. A computer program using Matlab is developed to analyze the behavior of frame analogy which is modeled from the couped shear wall structure. Several numerical examples are presented to verify the developed program with the commercial finite element package SAP2000. The numerical results proved that the proposed program is efficient and reliable. The proposed element and program are then applied to analyze a 30-story coupled shear wall structure with energy dissipation devices. As a result, the locations of the device that provide effective seismic resistance for a 30-story coupled shear wall structure are in the region from the 5th to the 15th floor or assigned on all floors.

Seismic design and engineering practice of 10‐story shear wall structure with replaceable viscoelastic coupling beams

SummaryStructures with replaceable energy‐dissipating elements are attractive systems for improving building resilience. Damage in these structures is mainly limited to dissipating elements, which can be replaced after earthquakes. Among the energy‐dissipating elements, viscoelastic dampers (VEDs) can dissipate energy even under small deformations while providing stable fatigue performances, which benefits high‐rise buildings in resisting both wind and earthquake loadings. This paper presents the seismic design of an engineering practice of a 10‐story shear wall building with replaceable viscoelastic coupling beams. A new type of viscoelastic material that has negligible frequency dependency is adopted to provide stable constraint for the wall piers. The design details, including VEDs, nonreplaceable segment, and the detachable connection, are exemplified. The numerical model of the replaceable structure is established and analyzed under dynamic loadings. Results confirm that the implementation of replaceable viscoelastic coupling beams improves structural seismic performance. The plastic rotation at the end of the coupling beam is significantly reduced up to 41.4% compared with the traditional coupled shear wall structure.

Hysteretic model for bending-type frictional steel truss coupling beams

As a novel coupling beam for coupled shear wall structures, the bending-type frictional steel truss coupling beam (BFTCB) concentrates the deformation and energy dissipation in friction dampers at the bottom chord, allowing the main body to remain elastic during earthquakes. As the preparatory work for resilient structure design based on the BFTCB, this work concentrates on developing the hysteretic model for BFTCB. Firstly, the BFTCB stiffness-strength decoupling mechanism was introduced, i.e., the shear strength is provided by friction dampers while webs control its initial stiffness. Secondly, a hysteretic model that reflects the BFTCB two-stage sliding characteristic was proposed. The model consists of a trilinear backbone curve and the unloading and reverse loading rules. The model has eight control parameters, of which two core parameters (initial stiffness and limiting shear strength) are derived from the BFTCB stiffness-strength decoupling mechanism, whereas the remaining parameters are obtained by theoretical analysis and empirical calibration. The hysteretic model was then compared with the test curves and demonstrated good accuracy. Finally, a series of FE prototypes of BFTCB with different design stiffnesses and strengths was adopted to verify the hysteretic model. The results showed that the proposed model fitted well with the FE prototypes, indicating its applicability to BFTCB with varying core design parameters. Therefore, the hysteretic model can be adopted for BFTCB to support the resilient shear wall structure design.

Development and investigation of an innovative shape memory alloy cable‐controlled self‐centering viscoelastic coupling beam damper for seismic mitigation in coupled shear wall structures

AbstractTo improve the seismic performance of coupled shear walls in high‐rise buildings and to eliminate the problems of large residual deformation and relatively small initial stiffness and damping properties of the traditional viscoelastic coupling beam damper (TVCBD), an innovative shape memory alloy (SMA)‐cable‐controlled self‐centering viscoelastic coupling beam damper (SVCBD) with energy dissipation and self‐centering capabilities was designed and investigated in this study. The construction form and operating principles of the SVCBD were proposed, relevant material performance tests of the cables were performed, and good results were obtained. Finally, the contribution of the SVCBD to seismic mitigation of a 10‐story reinforced concrete coupled shear wall structure was verified by seismic time‐history analyses. The results indicated that compared with TVCBD, SVCBD possesses fuller hysteretic curves, showing stronger energy dissipation capacity, higher initial stiffness, and much smaller residual deformation. The initial strain and cross‐sectional area of the SMA cables and the shear area of the viscoelastic plates affect the energy dissipation and self‐centering performance of SVCBD significantly. The seismic response and post‐earthquake residual deformation of the coupled shear wall structure and the plastic damage of the main components can be effectively controlled by utilizing the proposed SVCBD.

Analytical truss model with an extended strut for conventionally reinforced concrete coupling beams with span-to-height ratios larger than 1.75

Conventionally reinforced concrete coupling beams are widely used in coupled shear wall structures to improve the structural lateral stiffness and energy dissipation capacity. Therefore, it is of great significance to develop a simple mechanical analytical model that can accurately predict the shear strength and deformation of conventionally reinforced concrete coupling beams. In the previous work, the authors proposed an analytical truss model for coupling beams with the span-to-height ratio l/h ≤ 1.75. However, due to the changes in the load-transfer mechanism, the model is not suitable for coupling beams with l/h > 1.75. By comparing existing test results of coupling beams with different span-to-height ratios and numerical results provided by a refined finite element simulation, the evolution of the load-transfer mechanism with the variation of l/h is identified. On this basis, an analytical truss model that is consist of a novel extended strut and several secondary conventional struts is proposed. The proposed model is verified to predict the shear strength of 23 existing coupling beams well, with l/h > 1.75, and the coefficient of variation (COV) is of 0.092. In contrast, the design codes ACI 318–19 and GB 50010–2010 provide less accurate predictions (their COVs are 0.263 and 0.195, respectively). Moreover, the calculated shear force-transverse displacement skeleton curves using the proposed model are in good agreement with the test results. On the other hand, by simplifying the calculation process of this model, a simplified model is put forward for practical engineering application, resulting in a slight loss of accuracy (the COV is 0.109). In order to prevent the insufficient ductility of coupling beams with l/h > 1.75 with this simplified model, a standardized design method is also proposed.

Feasibility of using self‐sensing component and response prediction model for rotation monitoring of shear wall structures

SummaryThis study presents a designed framework of structural monitoring for coupled shear wall structures by integrating a theoretical response estimation model and a prototype micro‐voltage sensing module. Inspired by the deformation mode of coupled shear walls, a supplemental self‐sensing component is proposed for predicting the target flexural deformation. The self‐sensing component is designed to include permanent magnets and cross wires and installed parallel to the coupling beam. The relative velocity between the two attached walls is obtained using electromagnetic (EM) induction and measured micro‐voltages. Accordingly, the theoretical principle of the self‐sensing prediction model is then derived, and the calculation flowchart is presented. Illustratively, a detailed finite element model was performed in ABAQUS to investigate the feasibility and robustness of the proposed self‐sensing model under different excitation scenarios, and a parametric study is performed. Then, the nonstationary excitation is adopted to further investigate the performance of the self‐sensing model. Furthermore, an EM‐based sensing module for low‐level velocity measurement is developed and the prototype is tested by utilizing a shaking table test with satisfactory performance.

A Study on Coupled Wall System with Post-tensioned Steel Truss Coupling Beams: Concept and Performance Evaluation

In order to improve the seismic behavior of coupled shear wall structures, a new type of post-tensioned steel truss coupling beam (PSTCB) is developed in this paper. The PSTCB is composed of chord members, two diagonal buckling-restrained energy dissipaters and diagonally placed post-tensioned tendons. The energy dissipaters are expected to serve as fuses and can be quickly repaired after earthquake. Furthermore, the residual drift of the coupling beam can be reduced by the application of post-tensioned tendons in the diagonal direction. In the PSTCB, the post-tensioned tendons are anchored at outer ends of the wall piers. According to the Chinese code, an 11-story coupled wall structure was designed and the numerical model was developed in PERFORM-3D software. The seismic behaviors of the hybrid coupled wall system with PSTCBs (HCW-P), the hybrid coupled wall system with replaceable steel truss coupling beams and concrete coupled wall system with reinforced concrete coupling beams were evaluated and compared under maximum considered earthquake. Results showed that the HCW-P can achieve excellent lateral strength, stiffness, and ductility as well as reduce the residual displacements of the structure after earthquake.

Numerical assessment of the load transfer in steel coupling beam-reinforced concrete shear wall connection

The present work presents an accurate finite element model for conducting a nonlinear analysis of hybrid coupled shear wall structures. The FE model built in the commercial code Abaqus describes the response of in-plane reinforced concrete (RC) shear walls connected with steel coupling beams. The material nonlinearities of concrete, reinforcement and beam steel were considered. An experimental test on simple coupling beam specimens was chosen to investigate limitations of the previous researches on steel coupling beams, particularly with regard to load transfer to structural walls. It is found that the FE model predicts correctly the experimental results. Indeed, the load–displacement behaviour of the overall structure and the corresponding failure modes are correctly described. In the second step, a parametric study was conducted to examine the influence of the embedment length, steel beam profile and concrete strength on the behaviour of the connection. It is observed that increasing these parameters increases the strength in all cases, whereas the displacement stabilizes when the embedment length is greater than half the wall width and concrete strength exceeds 30 MPa. Moreover, the distributions of the compressive stresses at the steel profile-concrete contact surfaces in different cases show an average estimation of the length in the compression zone above and below the embedded steel section.

Distribution of Optimum Yield-Strength and Plastic Strain Energy Prediction of Hysteretic Dampers in Coupled Shear Wall Buildings

The structural behavior of reinforced concrete coupled shear wall structures is greatly influenced by the behavior of their coupling beams. This paper presents a process of the seismic analysis of reinforced concrete coupled shear wall-frame system linked by hysteretic dampers at each floor. The hysteretic dampers are located at the middle portion of the linked beams which most of the inelastic damage would be concentrated. This study concerned particularly with wall-frame structures that do not twist. The proposed method, which is based on the energy equilibrium method, offers an important design method by the result of increasing energy dissipation capacity and reducing damage to the wall’s base. The optimum distribution of yield shear force coefficients is to evenly distribute the damage at dampers over the structural height based on the cumulative plastic deformation ratio of the dissipation device. Nonlinear dynamic analysis indicates that, with a proper set of damping parameters, the wall’s dynamic responses can be well controlled. Finally, based on the total plastic strain energy and its trend through the height of the buildings, a prediction equation is suggested.

Seismic retrofit analysis of concrete coupled shear wall structures with laterally restrained steel plate coupling beams

Many existing deep reinforced concrete coupling beams that have low span-to-depth ratios are not desirable for seismic design due to their potential brittle failure with limited ductility and deformability. Previous experimental and numerical studies have demonstrated that the laterally restrained steel plate retrofitting method could effectively enhance the seismic performance of deep coupling beams. This article aims to develop a nonlinear finite element model based on the OpenSees software to accurately predict the behavior of coupled shear walls with or without laterally restrained steel plate coupling beams. The numerical results reveal that the seismic performance of the laterally restrained steel plate retrofitted coupled shear walls can be significantly enhanced. Furthermore, a genetic algorithm is adopted to determine the optimal positions of laterally restrained steel plate coupling beams. It is found that desirable seismic performance can be achieved by retrofitting coupling beams in the middle and higher floors of a building with coupled shear walls. However, only retrofitting coupling beams on the lower floors should be avoided because this could result in the serious degradation of the lateral load-carrying capacity and stiffness of the coupled shear walls.

Seismic behavior of coupled shear wall structures with various concrete and steel coupling beams

SummaryA novel 2‐level yielding steel coupling beam (TYSCB) has been developed to enhance the seismic performance of coupled shear wall systems. The TYSCB consists of a shear‐yielding beam designed to yield first under minor earthquakes and a bend‐yielding beam designed to yield under severe earthquakes. A comparison of seismic behavior of 4 20‐storey coupled shear wall structures with reinforced concrete coupling beams, complete steel coupling beams, fuse steel coupling beams, and TYSCB is presented. The dimensions and force‐displacement curves of these coupling beams are first designed. Nonlinear dynamic analyses on these structures are carried out under minor and severe earthquakes. The seismic behavior of these models is studied by comparing their storey shear forces, storey drift ratios and ductility demands. The results show that the base shear and storey drift of the structure with TYSCB under both minor and severe earthquakes are less than those of structures with concrete coupling beams and complete steel coupling beams. Furthermore, the ductility demand of coupled shear walls with TYSCB subjected to severe earthquakes can be greatly released compared with those using fuse steel coupling beams. This indicates that the proposed TYSCB has a better balance between ductility demand and energy dissipation, compared to traditional steel coupling beams.

An enhanced component based model for steel connection in a hybrid coupled shear wall structure: Development, calibration and experimental validation

In the present paper the development, calibration and experimental validation of two component-based models of dissipative steel links connecting a reinforced concrete wall to a steel gravity frame is presented.The dissipative capacity of such structures is greatly influenced by the effective hysteretic behavior of the wall-to-column coupling system. Within the present work, experimental tests results on two different configurations of wall-to-column coupling system are presented. The development and calibration of two non-linear cyclic component-based models, one for each configuration, are described, allowing a better understanding of the force transmission mechanisms and their influence on the global structural behavior.

The Effect of Spandrel Beam's Specification on Response Modification Factor of Concrete Coupled Shear Walls

Response modification factor (R factor) is one of the seismic design parameters to be considered in evaluating the performance of buildings during strong motions. This paper has tried to evaluate the response modification factor of concrete coupled shear wall structures with various length/depth ratios of spandrel beams. The effect of diagonal reinforcement of spandrel beam was also evaluated on the R factor. The R factor directly depends on overstrength factor and ductility reduction factor. For this purpose, three conventional structures with 5, 10 and 15 story buildings (having various spandrel beam's length/depth ratio with and without diagonal reinforcement) were selected and the nonlinear static analyses were conducted to evaluate their overstrength and ductility reduction factors. Also for a 5-story structure, nonlinear dynamic analysis (time history) was carried out in order to compare the results with nonlinear static analysis. It was concluded that the R factors using nonlinear time history analysis and nonlinear static analysis are almost the same. The results also indicate that by increasing the height of the structure, the overstrength reduction factor decreases; while the ductility reduction factor increases. Also, the response modification factor decreases with increasing length/depth ratio of spandrel beams. The coupled shear walls with diagonal reinforcement in spandrel beams have a greater R factor.

Seismic performance of special reinforced concrete coupling beams with diagonal reinforcement and headed bars

Special reinforced concrete coupling beams in high-seismic-risk regions require specific diagonal bundled reinforcement details that must be strictly followed to ensure proper structural performance. However, when these details are applied to coupled shear wall structures, the coupling beams' width must match the width of the walls, resulting in a complicated rebar layout and difficulty in on-site installation. Especially when applied with special shear wall structures, the joint between the coupling beam and the shear wall results in extremely complex reinforcement details that are almost impossible to install on site. With a view to overcoming such problems, this paper evaluates and reports on seismic resistance performance tests performed on coupling beams with a single diagonal reinforcement bar together with headed bars (DHB) reinforcement details, as a proposed alternative solution. Test results show that the test specimen HB75, in which the headed bars substituted for 75% of the capacity of the diagonal reinforcing bundled bars, had superior ductility and energy dissipation capability, as well as lower strength and stiffness degradation compared to other test specimens. Thus, this research indicates that the headed bars can be a practical alternative to hoops of diagonal bundled bars for confining concrete in coupling beams.

Testing and Behavior of Coupled Shear Wall Structure with Partially Post-Tensioned Coupling Beams

A 40%-scale coupled core wall structure with C-shaped wall piers and novel unbonded post-tensioned (PT) coupling beams was tested under quasi-static reversed-cyclic lateral loads combined with tributary gravity loads. This paper describes the design, analysis, and testing of this specimen, which included the bottom three stories, the tributary floor slabs, and a large portion of the foundation from an eight-story prototype structure. The upper five stories of the prototype structure were simulated analytically to impose forces and moments at the top of the test specimen. In addition to conventional sensors, the specimen was monitored using 14 digital image correlation (DIC) sensors, providing near-full-field response data of the most critical regions. Overall, the structure performed as predicted, validating the design approach. Strength loss at the end of the test was largely caused by the fracture of the vertical reinforcing bars in the wall pier toes at the base. The coupling beams performed well, demonstrating the advantages of the new PT system.