SEISMIC PERFORMANCE OF COUPLED SHEAR WALL BUILDINGS WITH REPLACEABLE ENERGY DISSIPATION DEVICES

Abstract

Performance of a structure in an earthquake is governed by its capacity to dissipate energy. In mid- to high-rise buildings, coupled shear walls act as efficient lateral load resisting and energy dissipation. Coupling beams, in coupled shear walls are designed to yield prior to yielding of walls. This provides higher energy dissipation capacity to coupled shear wall system as compared to uncoupled shear walls. Thus, the performance of coupled shear wall system is dependent on the energy dissipation capacity and ductility of the coupling beams. Various researchers have proposed different types and design of coupling beams, such as RC, steel, composite beams. Recently different types of fuses in coupling beams have been used and such systems are termed as Hybrid Coupled Wall systems. The use of steel as coupling beam provides high degree of ductility, acts as good energy dissipation system and has the added advantage of ease of construction compared to diagonally reinforced beam. Fuses in coupling beams are energy dissipation devices which have similar advantages as those of steel beam and can be replaced easily. Literature on different coupling beams consists with experimental evaluation of performance but little emphasis is there on use of beams in design to take advantage of higher dissipation capacities. The scope of this work consists in numerical modeling and design of a typical 15 storey building with coupled shear wall system, using guidelines of ACI 318, Euro-code 8, IS code and other available literature on design of Hybrid Coupled Wall systems. Design recommendations for coupling beams are reviewed such that they yield well before the walls yield. Design considerations for ductile performance of walls in coupled system is also reviewed. Placement of shear walls of different sizes and various locations is carried out and associated difficulties are discussed. The performance of building with different types of coupling beams is evaluated using nonlinear static procedures as per ASCE 41. From this study, it is observed that the Steel coupling beams with fuses display the maximum ductility as compared to other systems. The diagonally reinforced coupling beam displayed higher overstrength capacity. Model with steel beams showed less ductility compared to other models due to formation of flexural hinges which have less ductility compared to shear hinges