Two-Step Seismic Calculating Method and Seismic Features of SRC-RC Hybrid Frame Structure

Abstract

For further improving the seismic design of steel-reinforced concrete (SRC)—RC frame structures, a two-step seismic calculating method is proposed as a supplement to the current Chinese standard for structural seismic resistance design. In Step 1, internal structural forces are calculated by the modal response spectrum method and limited structural members’ internal force in the elastic level when the structure suffers frequent earthquakes. In Step 2, structural deformations are analyzed by pushover according to the moderate earthquake’s demand spectrum and controlled in a repairable level. A 20-story and 5×5 span initial frame structure whose columns are fully SRC and two SRC-RC frame structures that are replacing SRC columns of the initial frame structure in the upper stories by using RC columns were designed according to this two-step seismic calculating method. These three frame structures were analyzed using dynamic time history analysis by inputting rare earthquake waves. The research results show that all three structures can satisfy the safety requirements under rarely observed earthquakes. Moreover, some design suggestions for SRC-RC frame structures were provided according to failure modes and seismic performance of these three frames.