Vulnerability analyses of masonry structure under induced earthquake

The impact of earthquake induced by shale gas mining has attracted the attention of the government, academia and the public. It is of scientific significance and application value for the prevention and control of earthquake disaster risk to carry out seismic vulnerability research of induced earthquakes. There are significant differences between induced earthquakes and natural earthquakes in ground motion characteristics, and their seismic responses to engineering structures are also very different. In order to reveal the influence of induced earthquake and natural earthquake on the seismic effects of building structure and the distribution of failure probability of masonry structure, this paper takes typical masonry structure as the research object and develops the vulnerability study considering the effects of induced earthquake. At first, analysis models of typical three-story and six-story masonry structures are established, and then 40 natural ground motions and induced seismic ground motion with similar magnitude and epicenter distances are selected as inputs to the Pushover analysis. Finally vulnerability curves based on peak ground acceleration （PGA） and basic periodic acceleration response spectrum value S_a of the structure are established respectively. The cyclic loading method is used to analyze and discuss the structural collapse vulnerability under two induced earthquakes. The analysis shows that the induced seismic ground motion contains more high frequency components, while the natural ground motion has more low frequency components, when PGA is used as the vulnerability parameter, the vulnerability of natural ground motion is significantly higher than that of induced seismic ground motion. When S_a is used as the vulnerability parameter to input ground motion, the vulnerability curves of the three-story masonry structure are close to each other under the action of two kinds of ground motions because the basic mode is dominant. However, the high-order mode of six-story masonry structure has some influence on the seismic response of the structure, and the high-frequency components of induced seismic ground motion are more abundant than those of natural ground motion, so the vulnerability of six-story masonry structure under induced seismic ground motion is higher than that of natural ground motion. In addition, the cyclic loading method is used to analyze the vulnerability of masonry structures under the two induced earthquakes. The results show that the damage probability of structures increases obviously under the action of two induced earthquakes.