Hybrid Coupled Shear Wall Research Articles

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 behaviour of optimized hybrid coupled shear walls

AbstractThis paper shows the experimental structural behaviour of an optimized solution for hybrid coupled shear walls, which are seismic‐resistant systems composed of a reinforced concrete wall, with two side steel columns connected by beams ‐ the dissipative element. The optimized solution is proposed to upgrade the global behaviour of the system, with the aim of reducing the bending moment at the base of the reinforced concrete wall. Indeed, previous experimental tests demonstrated that the wall may suffer from early cracking at the base, despite the possibility of controlling the base bending moment thanks to properly balancing stiffness and resistance of the different components of the system. The optimized solution is numerically developed and designed with the philosophy of redistributing bending at the base of the wall by removing the lateral portions of the concrete and replacing them with a couple of steel hinged profiles, to control the deformations and absorb the torque. The central concrete part of the wall is kept but reduced to the minimum, to transfer the shear, only, reaching closely hinged‐like conditions. Two different solutions are proposed for the central reduced part of the wall: in the first case, the cross section is gradually reduced to the base, while in the second one, the wall is connected through a steel pin to the base. Both solutions are tested under monotonic load for a preliminary assessment of the actual benefits at the base of the wall compared to the original proposal.

Seismic performance of hybrid coupled shear walls

AbstractHybrid 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.

Experimental evaluation of post-tensioned hybrid coupled shear wall system with TADAS steel dampers at the beam-wall interface

Considering the optimal seismic resistance of coupled shear walls and the perks of self-centering systems, throughout this research, the hysteretic performance of post-tensioned concrete “Coupled Wall” (CW) subassemblies with “Steel Coupling Beam” (SCB) equipped with “Triangular Added Damping and Stiffness” (TADAS) steel dampers was experimentally evaluated. To dissipate the energy input from the earthquake, metallic yield dampers of the TADAS type were used at the connection zone between the beam and the wall in this structural system. Using a SCB rather than a concrete beam was suggested to reduce beam damage and maintain the system’s self-centering capabilities during lateral loading. High-strength steel strands were employed to generate post-tensioning along the beam’s longitudinal axis in the “Coupled Wall System” (CWS) to reduce structure residual deformation under seismic loading. In the first portion of this research, an experimental assessment of the load–displacement behavior of TADAS dampers exposed to cyclic loads was performed. Then, at floor level, three ⅔-scaled CW subassemblies were constructed using a post-tensioned SCB and subjected to lateral quasi-static cyclic loading of increasing amplitude. Various post-tensioning stresses were applied to one subassembly lacking energy dissipation devices and two subassemblies with TADAS dampers. The findings demonstrate that TADAS-equipped subassemblies can endure major non-linear deformations up to 8% drift without struggling either residual deformation or severe injury. Installing TADAS dampers at the beam-wall interface heightened the specimens’ capacity to withstand lateral loads by 71% to 90% and considerably increased their potential to dissipate energy.

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 behavior of hybrid coupled shear wall with replaceable U-shape steel coupling beam using terrestrial laser scanning

The hybrid coupled shear wall (HCW) with replaceable coupling beam (CB) is an optimal component to recover buildings promptly after a severe earthquake. However, the reinstallation may be difficult or impossible with an identical CB because of the inelastic relative dislocation between two wall piers. This study proposes a novel HCW with different reinforcement ratios in the connection, which was tested under cyclic loading. After the test, the bolt holes can be located through terrestrial scanning, which is then utilized to fabricate a new CB that can accommodate the deformation between two wall piers. The newly replaced HCW system was also tested. As a result, all virgin test specimens fail in web fracture and show a significant inelastic chord rotation of 0.2 rad, exhibiting an excellent energy dissipation capacity. Meanwhile, the new method to locate the bolt holes after the test is feasible. The replaced HCW fails in the pull-off of anchor bars and shows poor seismic behavior due to the unpatched concrete cover in the connection. To improve the energy dissipation for the replaced HCW, high-strength grouting in the connection can be used and high-strength material can be used to replace the usual anchor bolts.

Seismic displacements and behaviour factors assessment of an innovative steel and concrete hybrid coupled shear wall system

The objective of this research is to facilitate the design process of innovative steel and concrete hybrid coupled wall system, which is obtained through the connection of a reinforced concrete (RC) wall to two steel side columns by means of steel links. To this end, a group of 120 innovative hybrid coupled wall systems subjected to a set of 100 far-field ground motions are selected. Thousands of nonlinear dynamic time histories on the basis of incremental dynamic analysis (IDA) are carried out in order to generate a databank of specified response quantities. Subsequently, nonlinear regression analyses are conducted in order to derive simple formulae which offer a direct estimation of: fundamental periods of vibration, seismic displacements, ductility demands and behaviour factors q for both designed and undesigned structures at different limit states; involving steel first yielding of internal wall, various predefined maximum inter-storey drifts and links rotations values. The effect of the following parameters: number of storeys, coupling ratio value, steel area ratio of boundary elements, uniformity status of shear links, and length of links is thoroughly investigated. The results indicate that storeys number and uniformity status parameters have the largest influence on the most of response quantities. The current q behaviour factor value is approximately suitable for low-rise building, but it is highly underestimated in medium-rise buildings. Furthermore, the equal-displacement rule clearly overestimates the roof ductility. Overall, this study bridges the gaps about the innovative hybrid coupled wall system design methodology and enables a rapid seismic assessment of such structures.

Estimation and development of innovative hybrid coupled shear wall system using nonlinear dynamic and fragility analysis

The Innovative hybrid coupled shear wall system (HCW) is one of the most advanced economical structural systems which has already been conducted. It constitutes of RC shear wall connected to two side steel columns by mean of replaceable coupling steel links. The main design objective of this system is to withstand lateral loads with minimized or even no damage of non-replaceable components (i.e. RC wall and steel columns), while the replaceable coupling steel links could undergo severe damage. This system still highly lacks investigations and detailed estimation as well as being of low efficiency in low-rise buildings. In this research, the emphasis is upon the estimation of the most efficient current HCW systems which have been recommended in literature so far, to be thoroughly calibrated against equivalent conventional RC wall system. Furthermore, new recommendations are presented in intention of optimizing the performance of HCW system to efficiently achieve the design objective through multi-type modifications: links arrangement, internal wall structure and combined systems. The study implements an advanced modelling procedure and extensive nonlinear dynamic analyses with fragility assessment to obtain a highly reliable evaluation. The newly proposed methods reveal excellent efficiency, especially in low-rise buildings.

Experimental Study and Numerical Simulation on Hybrid Coupled Shear Wall with Replaceable Coupling Beams

The coupled shear wall with replaceable coupling beams is a current research hotspot, while still lacking comprehensive studies that combine both experimental and numerical approaches to describe the global performance of the structural system. In this paper, hybrid coupled shear walls (HSWs) with replaceable coupling beams (RCBs) are studied. The middle part of the coupling beam is replaced with a replaceable “fuse”. Four ½-scale coupled shear wall specimens including a conventional reinforced concrete shear wall (CSW) and three HSWs (F1SW/F2SW/F3SW) with different kinds of replaceable “fuses” (Fuse 1/Fuse 2/Fuse 3) are tested through cyclic loading. Fuse 1 is an I-shape steel with a rhombic opening at the web; Fuse 2 is a double-web I-shape steel with lead filled in the gap between the two webs; Fuse 3 consists of two parallel steel tubes filled by lead. The comparison of seismic properties of the four shear walls in terms of failure mechanism, hysteretic response, strength degradation, stiffness degradation, energy consumption, and strain response is presented. The nonlinear finite element analysis of four shear walls is conducted by ABAQUS software. The deformation process, yielding sequence of components, skeleton curves, and damage distribution of the walls are simulated and agree well with the experimental results. The primary benefit of HSWs is that the damage of the coupling beam is concentrated at the replaceable “fuse”, while other parts remain intact. Besides, because the “fuse” can dissipate much energy, the damage of the wall-piers is also alleviated. In addition, among the three HSWs, F1SW possesses the best ductility and load retention capacity while F2SW possesses the best energy dissipation capacity. Based on this comprehensive study, some suggestions for the conceptual design of HSWs are further proposed.

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.

Nonlinear Seismic Response Analysis of an Innovative Steel-and-Concrete Hybrid Coupled Wall System

This paper studies the seismic response of an innovative hybrid coupled shear wall (HCW) system, obtained through the connection of a reinforced concrete (RC) wall to two steel side columns by means of steel links. This structural solution is conceived to exploit both the stiffness of the RC wall, required to limit building damage under low-intensity earthquakes, and the ductility of the steel links, necessary to dissipate energy under medium-intensity and high-intensity earthquakes. The seismic performance of the proposed HCW system is evaluated through multirecord nonlinear dynamic analysis of a set of case studies designed on the basis of a specific ductile design procedure. The adopted finite-element models are illustrated and validated with experimental tests and more complex three-dimensional numerical models. A selection of results is presented and discussed to highlight the potential of the proposed innovative HCW systems and the possibility to develop a ductile mechanism in which plastic deformations are mainly attained in the steel links, with minor damages in the RC wall.

Performance-Based Seismic Design Of An Innovative HCW System With Shear Links based on IDA

Structural members yielding in shear are used in earthquake resistant systems, such as eccentrically braced steel frames and systems with passive energy dissipation devices, in a conscious effort to concentrate the energy dissipation capacity of the structure in components that can be repaired or replaced after a major earthquake. This paper presents an improved approach to a newly suggested design procedure of an innovative Hybrid Coupled Shear Wall (HCW) system consisting of a RC shear wall coupled with steel side columns via dissipative steel shear links. The primary design objective is to reduce or possibly avoid the damage in the RC wall while concentrating the seismic damage to the replaceable steel links which are shear critical, i.e. intended to fail in shear rather than flexure. To this purpose, a performance based approach is followed considering several limit states such as IO (Immediate Occupancy based on a limitation of the interstorey drifts), LS (Life Safety with yielding of the link, restoration possibilities of the links and limitation of the damages in the RC wall) and CP (near collapse situation with possible significant damages in the RC wall). The proposed design procedure is applied to several case studies which are analysed through nonlinear static and incremental dynamic analyses using finite element models in order to optimize the respective contribution of the wall, side columns as well as the links in terms of strength, stiffness and energy dissipation capacities.

Investigation of Stiffness Effect of Coupling Beam on Boundary Element Detailing in Structures with Hybrid Coupled Shear Walls

Coupled walls are known to be efficient lateral load-bearing systems. Coupling beam and wall piers are two important and effective elements in the general response of these structures. In this paper, stiffness effect of steel coupling beams on boundary elements in coupled shear walls has been investigated. The provisions of Iranian National Building Code for concrete structure (INBC-No. 9) for evaluating detailing requirements at wall boundaries are based on studies on uncoupled continuous walls, in which stress distribution across sections is assumed to be linear and in un-cracked sections. Due to the fact that there have been severe axial forces on wall piers resulting in the creation of cracks in sections of tension walls, the applicability of these provisions in coupled walls should be evaluated. Several coupled wall structures with different geometrical specifications, representative of various ratios of stiffness of the coupling beam to stiffness of the wall (RSBW), under equivalent lateral force, were designed, and efficiency of the code provisions was investigated in comparison with the results of the numerical analysis in Abaqus software. In this analysis, nonlinear behavior of material was considered. Results show that for structures with large and medium RSBW, code provisions are not appropriate in evaluating detailing requirements of tension wall boundaries, and a nonlinear stress distribution on the section should be used. For compression walls and structures with low RSBW, code provision is reliable.

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.

Experimental study of a replaceable steel coupling beam with an end-plate connection

In order to enhance the post-damage repair capability of the hybrid coupled shear wall systems, a different type of replaceable steel coupling beam with end-plate connection was investigated. Different from conventional configurations, the coupling beams were not embedded into the walls to minimize the post-event repair/replacement difficulties and expenses. To assess the seismic behavior and post-damage replaceability of the coupling beam, a two-stage experimental program was performed to test the full-scale specimens, each utilizing coupling beams with different strength and stiffness. The results of the first specimen indicated a ductile failure with a concentration of inelastic deformation at steel web and thus exhibited desirable deformation and energy absorption capacities with minimum damages to the shear wall. Again, on the minimum repaired wall-pier, the second specimen via the proposed connection, with improved characteristics such as strength and stiffness, was installed and tested. The results demonstrated excellent stiffness, strength, and ductility characteristics of subassemblages under cyclic loading, with considerable energy dissipation concentrated in the coupling beam web. Although the second specimen failed from the threaded area of the tensile bolts, due to increased coupling beam strength, the specimens were able to sustain large nonlinear displacements without significant damage in the connection to the wall pier regions; representing that this connection configuration would require little repair, if any, after a severe earthquake.

Experimental study of reinforced concrete and hybrid coupled shear wall systems

Two approximately half-scale four-story coupled shear wall specimens were tested under both gravity and lateral displacement reversals. Specimen CW-RC, featuring traditional reinforced concrete (RC) shear walls and RC coupling beams, sustained ductile hysteretic response up to 3.00% drift. Specimen CW-S, featuring RC shear walls and steel coupling beam with low yield point steel (LYP) web, failed after completion of 2.00% drift cycles. The proposed connection detailing between the steel coupling beam and RC shear wall worked well in Specimen CW-S. Research results indicate that a ductile coupling beam design does not guarantee a ductile behavior of a coupled shear wall system. RC shear walls should be proportioned for axial and shear based on the provided coupling beam capacities. Design recommendations are provided.

The Seismic Behavior of Pseudo Strain-Hardening Cemetitious Composites Coupling Beams with Polyvinyl Alcohol Fiber

This paper addresses the seismic behavior of pseudo strain hardening cementitious composite (PSH2C) coupling beams with different failure modes in hybrid coupled shear wall. Test variables included the ratio of steel coupling beam strength to beam-wall connection strength. The results show that Specimen PSH2C-SCF exhibits a better stable behavior in comparison with Specimens PSH2C-SBVRT and PSH2C-FCF.

Stiffness and Energy Dissipation of Steel Coupling Beam Embedded in the PSH2C and Normal Concrete Shear Wall

Hybrid coupled shear wall with steel coupling beams has often been used as load-resisting system of high-rise buildings under lateral loads. However, joint between steel beam and shear wall is under combined and high stress. Reinforcement details of the joint are very heavy. This study addresses the effect of shear wall cement composites type in hybrid wall system on the seismic performance of steel coupling beams embedded in shear wall. The main test variables were the failure mode of steel coupling beam and types of cement composites, such as PSH2C and concrete, for shear wall.

Panel Shear Strength of Steel Coupling Beam-Pseudo Strain Hardening Cementitious Composite Wall Connection

Hybrid coupled wall systems, where steel coupling beams couple two or more pseudo strain hardening cementitious composite (PSH2C) shear wall can be used in medium and high-rise construction subjected to earthquake. This paper addresses the panel shear strength of steel coupling beams - PSH2C shear wall connection. Test variables included the connection detail in hybrid coupled shear wall system. The results show that Specimens PSH2C-PSFF and PSH2C-PSFFT exhibits greater panel shears strength than Specimen PSH2C-PSF.

The Influence on Horizontal Ties of Steel Coupling Beams

Hybrid coupled shear wall system with steel coupling beams has known as the effective lateral load resisting system for tall buildings subjected to earthquake. This paper addresses the influence on horizontal ties of steel coupling beams in pseudo strain hardening cementitious composite (PSH2C) hybrid coupled shear wall. Test variables included the connection detail and types of material, concrete and PSH2C, in the connection region. The results show that Specimen PSH2C-SB and PSH2C-SBVRT exhibits a better stable behavior than Specimens HCWS-SB and HCWS-SBVRT.