Coupled Shear Walls Research Articles

Experimental study on joint’s seismic performance of a PCSW with thermal insulation elements

Precast coupled shear walls with thermal insulation elements (PCSW-T) are structurally and thermally efficient systems, which are deemed promising in precast structures. Nevertheless, the beam-wall joint may still function as a weak region during seismic events, which remains a fraught issue. In this paper, an innovative connection using double-section mechanical sleeve (DMS) systems was presented and investigated experimentally. Two monolithic and four PCSW-T joint specimens, evenly divided into two groups, were tested under reversed cyclic and pushover loadings, with beam shear-span ratios of 2.5 and 0.75, respectively. Experimental results revealed that the PCSW-T joints displayed similar damage modes to the monolithic ones under different shear-span ratios, while their seismic behaviors in terms of strength, deformation, stiffness, ductility, and energy dissipation were even better. Consequently, the PCSW-T structure can fulfill the design criterion of “equivalent to cast-in-place”.

Seismic behavior and nonlinear analysis of Hybrid Coupled Shear Walls

Hybrid Coupled Shear Walls are an innovative seismic-resistant system that aims at merging the advantages of the classical Coupled Shear Walls with the dissipative capacity and easy-to-repair characteristics of steel elements. They are constituted by a reinforced concrete wall connected to two side steel columns by dissipative steel links. Depending on the stiffness/strength of the links, it is possible to obtain different distributions of the seismic forces between the wall and the columns. As resulting from previous research activity on this topic, the seismic behavior of this structural system can be strongly influenced by the higher modes, especially for mid/high-rise buildings, making classical pushover analyses unable to catch the correct behavior. In this regard, the paper presents the comparison between the results of Incremental Dynamic Analyses and of different Pushover Analyses, giving indications about a more reliable procedure for the assessment of the seismic performance through suitable pushover analysis.

Seismic assessment of a new resilient coupled shear wall

An effective approach to designing a resilient structure following an earthquake is to incorporate reinforced concrete coupled shear walls in the system that consist of replaceable components. A prior experimental study has shown that the damage in such an innovative coupled shear wall is mainly concentrated in the replaceable components which comprises replaceable dampers in coupling beams and replaceable corner components in the wall. This paper presents a comprehensive evaluation of the seismic fragility and collapse safety of three buildings of varying height (seven, eleven and fifteen stories) with the proposed resilient coupled shear walls using incremental dynamic analysis (IDA). Finite element models are developed of a conventional system with coupled shear walls and the new system with replaceable components and validated by comparing simulated results with experimental findings. The exceedance probability of different performance levels is estimated and the collapse performance, such as collapse patterns, collapse margin ratios and probability of collapse are discussed and compared. Findings from the study indicate that the system with the new resilient coupled shear wall has a significantly lower probability of collapse than buildings with traditional coupled shear walls.

Calculations of additional axial force and coupling ratio for coupled shear walls

The additional axial forces (AAFs) in walls and coupling ratio (CR) of coupled shear wall (CSW) systems have significant effects on the local behaviors of the individual walls and the overall structural performance, respectively. A new analytical approach to obtaining AAF and CR for three different types of lateral loads has been proposed to avoid complex numerical simulations or time-consuming analyses. Firstly, a differential equation with respect to AAF was established using a concise expression of the external moment; AAF calculation method considering triangular, uniform, and top concentrated lateral loads was developed. Secondly, CR calculation formulas for three different types of lateral loads were derived based on the formulas of AAF and applied to simplify the formulas of calculating top lateral deflection of CSWs. Thirdly, the calculation method of AAF, CR and the simplified formulas of top lateral deflection were validated by conducting numerical simulations using ABAQUS and OpenSees. Finally, the advantages of the proposed methods as well as the impact of lateral load types and nonlinearities, etc. were discussed. It was found that AAF and CR could be efficiently calculated by the proposed approach for CSWs including asymmetric ones subjected to three typical lateral loads, and the relative errors compared with numerical simulation are less than 10%. Besides, different types of lateral loads affect the distributions of AAFs and the values of CR.

Effect of the Size of Multiple Perforations on the Performance of Long Reinforced Concrete Shear Walls

This paper investigates the effect of the size of multiple openings on the behavior of shear walls. In this study, the wall span is 24 m, the wall depth is 4 m, and is 0.3 m thick. The work involves the discussion of the three main kinematic and strength indicators that influence the shear wall performance. They are the load displacement relationship for the wall top edge, the equivalent concrete stress flow within the body of the wall, and the bending stress gradient at the bottom of the wall. The wall is constructed of reinforced concrete. A nonlinear finite element push over analysis has been carried out using Ansys software. The element Solid65 presented by Ansys effectively simulates the true behavior of concrete. The steel reinforcement has been modeled by link180 element. Primarily a finite element model for the solid bearing RC shear wall has been constructed and analyzed. The primary step has involved calibration and validation of the finite element model. Thereafter, pushover analysis has been performed for four perforated walls of various opening sizes. The study has indicated that when the percentage of the sum of the perforations’ areas to the total wall area surpasses 8.35%, the shear wall load carrying capacity starts to degrade. When the percentage of the sum of perforations surpasses 16.7% of the total wall area, the shear wall behavior starts to convert to that of two coupled shear walls. The larger the opening size is, the higher the stresses are, and the less the wall load carrying capacity is. When the percentage of the sum of the perforations’ areas to the wall total area surpasses 25%, the behavior of the shear wall converts to that of a frame. The study recommends that further future studies should be carried out on the effect of providing CFRP sheets on the edges of the openings, especially at lower stories in order to control concrete cracks at the edges of the perforations resulting from the developed large concrete equivalent stresses.

Nonlinear behaviour of FRP-retrofitted RC coupled shear walls

This paper presents a numerical study of the effectiveness of fibre-reinforced polymer (FRP) composites in upgrading the seismic performance of conventional reinforced concrete (RC) coupled shear walls. The study investigates the performance of two RC coupled shear wall buildings with different heights when their coupling beams are retrofitted using FRP U-wraps for increased ductility of the beams. The 10- and 15-storey existing buildings are located in Montreal, Canada, and were designed according to the 1970 National Building Code of Canada (NBCC). The FRP retrofit aims to increase the shear capacity of nominally ductile coupling beams, and hence increase their rotational ductility to the limited ductility, moderate ductility, and ductile levels. Nonlinear incremental dynamic analyses were conducted for existing and FRP-retrofitted buildings when subjected to twelve ground motion records with different frequency contents. The seismic behaviour of the analyzed cases was compared based on the maximum earthquake intensity that can be resisted by the building, maximum interstorey drift ratio, maximum storey shear, maximum coupling moment, maximum energy dissipated, and maximum wall forces. Moreover, the twelve earthquake records were scaled to match the NBCC 2015 design response spectrum of Montreal to determine the optimum retrofit level for the coupling beams of the two buildings in consideration.

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.

Seismic performance of flexure-dominated reinforced-engineered cementitious composites coupled shear wall

The feasibility of using engineered cementitious composites (ECC) to improve the seismic performance of coupled shear walls was investigated experimentally and analytically. Reinforced-ECC (RECC) coupled shear wall was tested under cyclic loading for comparative study with its RC counterparts. Important seismic performance indicators, such as the deformation mode, damage pattern, stiffness, ductility and energy dissipation of the two coupled shear walls were compared and analyzed. The RECC shear walls and RC shear walls exhibited flexural failure modes with different damage patterns. The damage was concentrated mainly in the plastic hinge area, which include the bottom of the wall and the ends of the coupling beams. The RECC shear wall exhibited smeared cracking characteristics with a significantly smaller crack width. The RECC members showed ductile failure mode without crushing or spalling, and provided effective restraint to the longitudinal rebar, which delayed the buckling of the longitudinal rebar. The deformation capacity of the RECC shear wall was twice that of the RC shear wall, and the energy dissipation capacity of RECC shear wall also improved significantly compare to RC shear wall. The RECC shear wall exhibited a slightly higher load-bearing capacity compared with its RC counterpart. The ultimate strength of the RECC and RC coupled shear walls were estimated based on the compression–bending mechanism. The calculated results agreed well with the test results. The estimated yield and ultimate displacement of the RECC and RC shear walls were close to the test results.

Design and cyclic testing of bolted end plate connections between steel link beams and cross-laminated timber for coupled shear walls

Coupled cross-laminated timber (CLT) wall systems with ductile steel link beams offer an efficient, high-capacity lateral load resisting system for buildings in earthquake-prone regions. This study proposes a type of beam to CLT wall connection using a bolted end plate in a notched CLT panel edge to create a semi-rigid joint. A simplified analytical method is proposed to predict the connection strength and is compared against the results of full-scale experiments. The experimental strength values were all greater than the predictions from the proposed method. Therefore, the strength method seems conservative and is suitable for the capacity design of similar connections in coupled wall systems. The final specimen in the test programme was capacity designed and its cyclic test results demonstrated adequate connection strength and relatively high stiffness were achieved for a 200 mm-deep wide flange link beam. The specimen’s link beam yielded at an applied shear load of 180kN and reached a maximum strength of 278kN while dissipating a large amount of energy through steel yielding. The bolted end plate connection appears to be a practical solution for application in coupled CLT shear walls.

Seismic Behavior of Coupled Shear Walls made with Ductile Fiber-Reinforced Cement-Based Composite

Seismic Behavior of Coupled Shear Walls made with Ductile Fiber-Reinforced Cement-Based Composite

Seismic Performance of Coupled Steel Plate Shear Walls with Different Degrees of Coupling

Seismic Performance of Coupled Steel Plate Shear Walls with Different Degrees of Coupling

Test, Analysis, and Seismic Design Approach of RC Infill Walls Isolated by PVC Tubes in Coupled Shear Wall Systems

Test, Analysis, and Seismic Design Approach of RC Infill Walls Isolated by PVC Tubes in Coupled Shear Wall Systems

Simplified Design of Coupled Shear Wall Systems for Typical Building Configuration

Simplified Design of Coupled Shear Wall Systems for Typical Building Configuration

Analytical Structural Health Monitoring of Shear Wall Building

Abstract: Structural health monitoring techniques have been utilized to inspect the current conditions of structures, as well as their post-earthquake performances. The dynamic characteristics of a building, such as modal periods, shapes and damping ratios can be obtained by analysing the ambient vibration data. It is well-known that dynamic characteristics generated from the finite element model (FEM) and vibration data, even for the intact building, show remarkable differences. Assumptions made in the FEM are one of the main reasons for those differences. To examine feasible solutions to such problems mentioned above Here an attempt has been made to study the behaviour of different structures of reinforced concrete with different heights with and without shear walls. Coupled shear walls have also been studied to understand the comparative merit or demerit of framed structures with shear wall structures. Studies have been carried out on sample model structures and analysis has been carried out by ETABS software. It has been ensured to consider sample models that represent the current practices in structural design to include different structural configurations. Models having varied structural configurations like framed, shear wall, coupled shear wall, central core shear wall, core in core etc. have been taken into consideration. The inherent asymmetry present in the structures have also been dealt. Natural frequencies and mode shapes of the structure were determined by frequency domain decomposition method. In addition, identification of damping was performed due to the fact that damping ratio plays a significant role in the magnitude of inter-story drift during an earthquake. The FEM of the structure was constructed based on design drawings and updated to represent the real mode shapes and frequencies of the structure. By using the updated FEM with standard damping ratio in Indian Earthquake Code and the identified damping ratio, seismic performance assessment of the building for a possible earthquake.

Analysis of Vertically Oriented Coupled Shear Wall Interconnected with Coupling Beams

The nonlinear static response of a vertically oriented coupled wall subjected to horizontal loading is presented in this research article. The 3 storey vertically oriented coupled wall interconnected with coupling beams is modelled as solid elements in a finite element (FE) software named Abaqus CAE and the steel reinforcement is modelled as a wire element. For simulation of concrete models, a concrete damaged plasticity constitutive model is taken into consideration in this research. Moreover, with the help of concrete damage plasticity parameters, validation of two rectangular planar walls was executed with an error of less than 10 percent. Finally, these parameters are used for modeling and analyzing the static behavior of coupled walls connected with coupling beams. Furthermore, the maximum unidirectional horizontal loading helped in obtaining the compression and tensile damage as well as scalar stiffness degradation. Significantly, the research also found the plastic hinge location in the coupled wall as well as in the coupling beam, which are of utmost importance in nonlinear analysis. Doi: 10.28991/HIJ-2022-03-02-010 Full Text: PDF

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.

Introduction of a new metallic-yielding pistonic damper for seismic control of structures

A new damper with pistonic performance is presented in this research for seismic control of structures. A set of rectangular metallic yielding plates has been considered as the energy dissipating part for this device. The damper is configured in such a way that can provide the loading conditions as pure-bending for this part during cyclic motions. This configuration makes the damper to have an optimized flexural yielding mechanism and consequently a high-level of force capacity and damping ratio. The dissipator part is placed into a steel surrounding rigid box which has only one sliding translational degree of freedom along its longitudinal axis. Accordingly, the device can perform as a tension/compression piston with sufficient stability in other directions. The proposed metallic-yielding pistonic (MYP) damper can be used in various types of structural systems such as moment-resisting or braced frames and even coupled shear wall systems with the capability of dual or multiple-installation in each frame bay. In this research the hysteresis behavior of this damper has been numerically investigated. Then as a parametric study, the effects of various MYP design parameters on the damper hysteretic behavior were studied. Finally, the control performance of this device was seismically investigated in a one-story moment-resisting frame considering possible beam flange out-of-square imperfections. According to observed results, the proposed damping system is high-performance in seismic structural protection at low-value story drifts. Besides, it was able to significantly reduce the structural responses and residual deformations as well as the out-of-plane frame motions.

Investigating the Behavior of Coupled Steel Plate Shear Wall under Cyclic Loading

Investigating the Behavior of Coupled Steel Plate Shear Wall under Cyclic Loading

Equivalence of plastic strength and hysteretic behavior of box and I-shaped shear links

In seismic resilient structural systems like eccentrically braced frame and coupled shear wall system, a small beam-like segment known as the shear link is used as a replaceable structural fuse. Shear links dissipate seismic energy primarily by shear deformation. This study focuses on the numerical investigation of the shear capacities of short box-shaped and I-shaped links and the feasibility of interchangeability between them. For replacing links in post-disaster periods, this interchangeability between links of different shapes would allow designers to choose from a wider range of options leading to higher flexibility. Existing equations for the prediction of shear capacities were studied to find appropriate equations to be used for achieving equivalent hysteretic behavior by links of I-shaped and box-shaped sections. When shear capacities are estimated with the existing equations of the AISC code, the hysteretic behavior of a box-link differs from that of an I-link despite having the same shear capacity. These equations do not take into account the contribution of flanges in the resistance of shear forces. Instead, the alternative equations which include the full link depth are found to be more appropriate using which the same cyclic behavior can be achieved by either a box-link or an I-link (with the same shear capacity) in terms of hysteretic response, overstrength, and energy dissipation. An I-shaped link can be replaced with a box-shaped link of the same capacity and vice versa, when capacity prediction is done with the suggested equations.

Seismic Performance and Cost Analysis of UHPC Tall Buildings in UAE with Ductile Coupled Shear Walls.

The superior mechanical characteristics of ultra-high-performance concrete (UHPC) have attracted the interest of many researchers worldwide. Researchers have attempted to perform comparative analyses on the behavior of UHPC versus conventional and high-strength concrete, with their aim being to gain more insights into the difference between different types of concrete. However, the current state-of-the-art revealed no direct comprehensive comparisons between their behaviors in ductile coupled shear walls under seismic loading. This paper explores a comprehensive side-by-side comparison in terms of seismic behavior and cost analysis for four 60-story archetype buildings. The reference building was designed using high-strength concrete with a strength of 60 MPa. The other three archetype variations incorporated three different UHPC grades: 150 MPa, 185 MPa, and 220 MPa. The plan configuration and the lateral force-resisting system (LFRS) were chosen according to the most common practice in the UAE. The main objective is to report the effect of UHPC on the LFRS (ductile coupled shear walls). Moreover, a simplified initial cost analysis (materials and labor) design was performed. The findings of this paper indicate that the use of UHPC is capable of improving the seismic performance behavior of the lateral system as well as reducing the total initial costs.