Comparison of Unbraced, Braced and Shear Wall structure Performance under Seismic Loads

Abstract

The losses to infrastructure and human life, occurred in past from earthquakes, demands that the structural engineers should incorporate the loads associated to earthquakes and design safe structures. In all design approaches, a single thought process is common: Capacity > Demand. In case earthquake forces the demand is estimated based on intensity and recurrence of an event. In regions of high seismicity, the demand is higher and for a moderate to low seismic zones this demand will be less. The corresponding strength varies accordingly. In certain cases, it has been observed, due to uncertainty in estimation of demand, that much higher capacity is provided. This study highlights the role of shear wall and bracing in enhancing the seismic performance of the structure. An eleven story, fixed base structure, is modelled on ETABS and analyzed under application of time history of 2005 Earthquake recorded at Abbottabad. In this study, the performance unbraced structure is compared with braced and shear wall structure. Steel bracing have been used in structure in the arrangement of X and V. The variation in performance of the structure due to bracing arrangement is also studied in this project. In order to carryout comparison four different models are created i.e unbraced, x-bracing, v-bracing, and shear wall structure. Then seismic load combination is set in ETAB and applied in X and Y direction on the structure. In this project a software approach has been adopted to evaluate the performance of shear wall structural system and braced structure. The performance of all the structural systems have been compared. A gradual process has been adopted to show comprehensible contrasts between the systems.