Effect of steel coupling beam on the seismic reliability and R-factor of box-type buildings

Abstract

In reinforced concrete structures comprising box-type (tunnel form) structural systems, although the link beams (LBs) experience heavy damage before the shear walls, dimensional and cross-sectional limitations make it challenging to design LBs as seismic fuses. In this study, replaceable steel coupling beams were considered as an alternative to concrete LBs and the seismic performance, seismic reliability and multi-level response modification factor of this new system was examined. The results showed that the steel LBs had considerable effects on the lateral stiffness and load-bearing capacity of the box-type structural system. Under design and maximum credible earthquakes, the steel LBs had less influence on the performance level of the structural walls, which are the main elements of the lateral-load-bearing system. Consequently, they will slightly reduce the seismic reliability of the system while achieving predetermined performance levels. The use of steel LBs is suggested due to their replaceability and high energy-absorbing capacity.