SEISMIC VULNERABILITY OF RC FRAME BUILDING WITH VARIATION IN EFFECTIVE STIFFNESS

Abstract

Due to cracking, there will be a substantial reduction in flexural stiffness which ultimately results in larger deflections. Member stiffness is commonly considered as the gross stiffness, or as the effective stiffness which is an approximate percentage of gross stiffness, in the study and design of reinforced concrete (RC) buildings. NBC 105:2020 recommends the use of effective stiffness of cracked sections during analysis, however it is not addressed in NBC 105:1994. Several configurations of moment- resisting frames, regular in plan and elevation, with variation in the number of bays and storey number are designed and analyzed by using gross and cracked section properties. The motive of this research is to study the effect of the modeling approach of building in terms of gross and cracked sections on the structural performance under earthquakes. Non-linear static analysis is done in ETABSv19 to evaluate the overstrength and ductility of structures designed using gross and cracked section properties.