Correlation Analysis of Ground Motion Duration Indexes and Nonlinear Seismic Responses of a Long-span Continuous Rigid-Frame Bridge with High-Rise Piers

To investigate the correlations of duration indexes and the nonlinear seismic responses of long-span continuous rigid-frame bridges with high-rise piers (CRFB-LH), an irregular CRFB-LH was selected as the prototype bridge. A construction stage analysis model was simulated in MIDAS/Civil, where the actual construction process was considered and the internal force state was extracted. After that, a nonlinear dynamic analysis model of the CRFB-LH with the equivalent internal force state was simulated via OpenSees. A bracketed duration and significant duration with a continuous-time interval were selected as the duration indexes. Sixty ground motion records with total duration values ranging from 9.91 s to 300 s were used in the nonlinear dynamic analysis. The correlation between the two duration indexes and the nonlinear seismic responses of the CRFB-LH under total-duration ground motions were analyzed. Finally, the effect of different duration indexes on the nonlinear seismic responses of the CRFB-LH was discussed under 30 long-duration ground motions intercepted according to Db0.1g, Ds5-75% and Ds5-95%. The numerical results show that the correlations of Ds with nonlinear seismic responses are better than those of Db, and the latter heavily depends on the absolute acceleration threshold. Ds5-95% is preferred for calculating the total hysteretic energy dissipated (HED) from the CRFB-LH. Additionally, while the amount of total HED is not determined by the total duration, the effective time interval of the ground motion duration under different duration indexes has a significant influence on the total HED.