Evaluation of ground motion intensity measures for time-history dynamic analysis of isolated bridges

• Published in: Structures (Oxford) 2023-09, Vol.55, p.1306-1319
• Main Authors: Dai, Jian-Cheng, Wang, Dong-Sheng, Chen, Xiao-Yu, Zhang, Rui, Sun, Zhi-Guo
• Format: Article
• Language: English
• Subjects: Cloud analysis; Geometric mean of response spectrum; Isolated bridges; Near-fault ground motion; Optimal intensity measure
• ISSN: 2352-0124; 2352-0124
• DOI: 10.1016/j.istruc.2023.06.007

The ground motion intensity measure (IM) is an important part of probabilistic seismic demand analysis and is used to predict the seismic response of structures. In this study, two typical isolation bridges are selected as cases, and 80 far-fault and 40 near-fault ground motions are used as inputs for the time-history analysis. By performing a comparison with 19 common IMs, it is proved that the IM based on the geometric mean of the response spectrum is an optimal choice for isolated bridges. The effects of response spectrum type and period range on this form of IM are investigated. The results show that the response spectrum type has a slight effect on the IM based on the geometric mean of the response spectrum, and the period range has a greater impact on the IM. The effects of the upper and lower limits of the period range of this IM are illustrated. The applicability of the IM to the far-fault ground motions and the near-fault ground motions is finally discussed. It can be concluded that when only near-fault ground motions are considered, the period range of the IM should be appropriately increased.