| dc.description.abstract | Taiwan uses the same seismic design values for areas with different earthquake intensity. In addition, Taiwan develops high-strength reinforced concrete in recent years, but the code does not have design values for high-strength. Therefore, the objective of the study is to investigate the difference between the seismic design values of high strength and normal strength RC beams, and to discuss their relationship with drift ratio.
This plan collects, organizes and analyzes the data tested from RC beams subjected to cyclic loading. Those beams having the longitudinal reinforcement of SD420, SD490 and SD690 represent as normal strength and high strength RC beams, respectively. The effective initial stiffness (K_{eff}) of the RC beam is obtained by adopting Paulay’s (1992) method. Meanwhile, the study adopted the Brooke’s (2011) method to calculate alpha_{mat} and alpha_{har} of the steel bar. The purpose of adopting Brooke’s method is to find the relationship between drift ratio and alpha_{har}, and their difference between normal strength and high-strength RC beams.
The results show that the effective moment of inertia (I_e) of the RC beam decreases with the increase of concrete compressive strength and increases with the increase of span-to-depth ratio, and the recommended value in some codes overestimates the actual value. The statistical results show that there is no significant difference in the value of the overstrength factor of strain hardening, that is, the value of alpha_{har} is independent of the steel grade, but it has a linear increasing with the increase of the drift ratio. Moreover, the recommended value of alpha_o in ACI 318-19 is too low. | en_US |