Probability assessment of structural response modification factor of RC frames by the demand-capacity-factor method

The values of structural response modification factor R are fundamentally critical in the specification of design seismic action for buildings. However, there are significant differences in the values of R in the codes or standards in different countries. In this paper, 15 reinforced concrete (RC) frames with 3-story, 5- story, 8-story, 10- story, and 12-story for design basic earthquake acceleration 0.05 g, 0.10 g, and 0.20 g are designed using the R≈3 implicit in the current Chinese codes. The accuracy of finite element models is verified via data from the shaking table test. A Demand-Capacity-Factor Method (DCFM) is used to evaluate R. The results show that the RC frames designed using the R≈3 and redesigned using the R≈6 can all meet the expected safety goals-against collapse under major earthquakes. The R≈3 implicit in the current Chinese codes are relatively conservative and the seismic influence coefficient curves under minor earthquakes should be improved.