Vulnerability assessment and collapse simulation of unreinforced masonry structures subjected to sequential ground motions.

Autor: Shen, Jiaxu, Zhang, Yongqun, Chen, Jun
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Zdroj: Bulletin of Earthquake Engineering; Dec2022, Vol. 20 Issue 15, p8151-8177, 27p
Abstrakt: An unreinforced masonry (URM) structure damaged by a strong earthquake may be threatened by subsequent aftershocks in an unrepaired state. However, there is no consensus regarding whether aftershocks must be considered in the design and retrofitting of URM structures. This study aimed to comprehensively evaluate the seismic performance and explore the collapse mechanism of URM structures subjected to sequential ground motions. Therefore, a refined numerical model of a 5-story URM structure was established and verified using experiments. Fifteen as-recorded sequential ground motions were screened from several databases. By employing the incremental dynamic analysis approach for mainshocks and aftershocks separately, 900 samples of nonlinear structural responses under different sequential ground motions were obtained. The inter-story drift ratio (IDR) and damage index (DI) were adopted to assess the vulnerability of the URM structure. Moreover, the entire process from the cracking to collapse of a URM structure was simulated to investigate the collapse mechanism caused by aftershocks. The results indicated that a strong aftershock poses a significant threat to the URM structure, and the probability of severe damage and collapse increases significantly. The influence of strong aftershocks on the URM structure is more significant in the DI-based vulnerability assessment than in the IDR-based one. A strong aftershock significantly aggravates the damage to parts previously damaged by the mainshock and has less impact on the undamaged parts. We conclude that a strong aftershock should be considered in the design and retrofitting of URM structures. [ABSTRACT FROM AUTHOR]
Databáze: Complementary Index
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