Research On The Seismic Response Of RC Eccentric Frame Structure Under The Mainshock-Aftershock

Theoretical research and earthquake experience show that the translational and torsional coupling effects cause the eccentric structure more damage in the earthquake, and the structure under the mainshock-aftershocks tends to show greater damage, therefore, there is important significance in researching on seismic response of eccentric structure under the mainshock-aftershock. The paper make use of OPENSEES program to establish the three-dimensional finite element models of regular structure and irregular structures of different eccentricity. Under the mainshock with different amplitude and aftershocks of amplitude modulation, the structure in different mainshock accordingly get the injury again because of the aftershocks.The main research content of this paper is the response of unidirectional eccentric structure and bidirectionally eccentric structure due to irregular mass layout under one-way and two-way mainshock and aftershocks input. The main contents are as follows:1. In this paper, the OPENSEES program is used to establish the mass eccentricity model of 0%, 10%, 5%, 15%, 20%, 30% eccentric, and the model is divided into unidirectional eccentric structure and bidirectionally eccentric structure, then the modal analysis is carried out.2. Unidirectional eccentric structure of one-way/two-way mainshock and aftershocks, we find that with increasing eccentricity of the structure, the top displacement, the interlayer displacement angle will show a growth trend. The response of the structure is further increased in the role of the one-way main-aftershocks. Under mainshock of 0.15 g, the largest aftershock top displacement is 1.4 times of the top dispalcement of mainshock, interlayer displacement angle of aftershocks can be achieved 1.5 times of the main shock. Generally speaking, when the structure is in an elastic state, aftershocks amplitude modulation effect will be more pronounced. The same discover is also for structure on bidirectional loading Compared with the structure under bidirectional loading, the impact of aftershocks amplitude modulation shows more sensitive to the structure under unidirectional loading.3. Bidirectional asymmetric structure in both directions of the mainshock and aftershocks,we find that with increasing eccentricity, a tendency to increase structure response presented in general. Compared with unidirectional eccentric structure, displacement of bidirectionally eccentric structure trends positively correlated more complex. By comparing the twist angle, it indicates the slightly reverse effect on bidirectionally eccentric structure than unidirectional eccentric structure. When experienced 0.15 g of mainshock, the maximum top displacement of aftershocks is up to 1.5 times the displacement of the mainshock, interlayer displacement angle under aftershocks is up to 1.4 times of that under mainshock. Compared with unidirectional eccentric structure, the impact of aftershocks amplitude modulation shows more sensitive to the bidirectionally eccentric structure.