Evaluation of Damage Index of Eccentrically-Braced Frames according to Link Beam’s Length with Soil-Structure Interaction Effects

Abstract

Due to features such as ductility and stiffness, the eccentrically-braced frames(EBF) have a good performance against seismic loads and have been considered by designers. Previous studies indicate that the soil underlying the structures affects their seismic behavior. In the case of EBFs, the link beam plays an imporatnt role in the seismic behavior of the system and thus, investigation into the effect of the geometric characteristics of the link on general behavior of the system, would be of utmost significance. In this respect, length of the link beam has been considered as the main variable in this study, taking the effects of soil-structure interaction (SSI) into account.Dynamic time-history analyses considering different lengths for the link beam with and without inclusion of the SSI, have been conducted, aiming to obtain damage indices. The results indicate that as the length decreases, in retrun, damage index (DI)increases and vice versa. Additionally, it was found that when the ratio of length of the link to that of the bay is approximately equal to 0.5, the DI values drop significantly. Also, results showed that considering the effect of SSI, applied general changes on the value of D, and showed different effects at various lengths of the link beams.