Hybrid Coupled Walls with Replaceable Shear Links: Technical Solution and Seismic Performance of a 3D Multi‐Story Building

Abstract

Two important aspects related to the design of building structures in seismic areas imply assuring: (i) an adequate seismic performance; (ii) the possibility of structural repair (i.e. replacement of yielded dissipative members). The focus of many researchers and engineers-in the last decades-has been on the development of innovative solutions fulfilling these conditions. One example is represented by the development of the "coupled shear wall" system. Later, a more advanced approach was made with the "hybrid coupled wall" system, and recently with the "single-pier hybrid coupled wall" system. The "coupled shear wall" system, which is composed of reinforced concrete (RC) shear walls and RC coupling beams (i.e. placed at floor levels), was introduced by [1] [2] for a better exploitation of the stiffness, strength and dissipation capacity of the RC walls. Beside some advantages, the main disadvantage of the system is represented by the special reinforcement detailing required for the coupling beams and for the area in their vicinity. This resulted in construction difficulties, the need for highly skilled workers and elevated costs. Furthermore, the limited shear capacity of the coupling beams often implied the need of deep cross-sections [3]. Within the "hybrid coupled wall" system, the RC beams were substituted by steel beams [4], which were aimed as structural fuses, getting most of the damages and being later easily replaced. Steel beams are of great advantage in case of height restrictions, or when the required capacity and stiffness cannot be economically assured by RC coupling beams. According to [5], HCW systems are usually built in combination with steel framing systems, i.e.: (i) coupled core walls; (ii) coupled shear walls located on the building's perimeter. Steel coupling beams dissipate energy similarly to the shear links in the eccentrically braced frames (EBFs), and can be short / intermediate / long links. The HCW systems offer an optimal combination of stiffness, strength and ductility-leading to adequate seismic performance. ORIGINAL ARTICLE Abstract As recent research findings evidenced a significant potential of the steel-concrete hybrid coupled wall (HCW) systems, further research activities are still needed for addressing particular issues and for developing advancements in the analysis, design, and detailing. These aspects are currently being addressed within the ongoing European research project "HYCAD", which also represents the research framework of the current study. This paper investigates through a set of nonlinear static and dynamic analyses the behavior and the seismic performance of a newly introduced steel-concrete HCW system. In particular, a case-study was carried out on a 3D multi-story building structure with perimeter lateral load resisting frames, each composed of: (i) a HCW, i.e. a steel-concrete composite wall coupled to steel columns through a set of replaceable steel shear links; (ii) a moment resisting frame (MRF). Beside a brief state of the art, a description of the research framework and the case-study structural system, the current paper makes an overview of the following: (i) experimental program on components; (ii) proposed technical solution for connecting the replaceable dissipative shear links to the composite wall; (iii) experimental test setup ; (iv) response of the shear links based on pre-test FE investigations; (v) seismic demand in terms of rotation for the shear links.