SEISMIC PERFORMANCE EVALUATION AND RESPONSE ANALYSIS OF RC HIGH-RISE BUILDING
UNDER STRONG GROUND MOTION IN DHAKA, BANGLADESH
Supervisor: Taiki SAITO
In recent years, construction of high rise buildings has increased as part of the ongoing development in Dhaka because of rapid urbanization and high population density. Due to lack of upgraded building code, legal enforcement, design and construction practices, existing high-rise buildings need to be assessed considering the current seismic demand to avoid any disasters due to seismic events. Therefore, evaluation of seismic performance of existing high-rise buildings has become essential. This study presents several analytical procedures to determine the performance of existing high-rise buildings subject to seismic force by relating the performance requirement of buildings. An existing RC high-rise building in Dhaka was selected for dynamic analysis considering different ground motions. The results obtained from dynamic analysis were also verified by conversion of the structure to equivalent single degree of freedom (ESDOF) and lumped mass model to examine the validity and applicable extent of these procedures. In addition, the capacity spectrum method by using equivalent linearization technique comprising equivalent damping ratio and response acceleration reduction factor was presented and verified with the results obtained from non-linear dynamic analysis. A reduction factor of 0.4 was proposed in this study for reducing the equivalent damping ratio (heq) due to inherent variability in earthquake motion. The results obtained by different procedures are compared. It is found that ESDOF and CSM have been given a fair agreement with the frame model except lumped mass model showing higher drift in upper stories due to dynamic amplification and effect of higher modes. In case of story shear force, lumped mass model showed similar results with small variations compared with the frame model. ESDOF and CSM provided similar results except three bottom stories due to large variation in story stiffness. Therefore, analytical procedures followed in this study can be used for performance evaluation of existing high-rise buildings to determine the seismic performance as per current demand provision in Bangladesh National Building Code (BNBC).