The Analysis Of Translational-torsional Coupling Response Of Base-isolated Eccentric Structures Under Random Excitation

Due to the various styles of modeling and overall arrangement of building structures, the mass centre of the structure and rigidity centre is always not coincident, so the translation-torsion coupling response may be induced under earthquake excitation by reason of structural eccentricities. Theory analysis and seismic disaster has shown that torsional response results in rapid destruction. In some cases, it even becomes the main factor causing the structural failure, so many researchers have focused increasing attention and efforts to this problem and significant progress has been made in this field. With regard to this point, the study on structural response of eccentric base-isolated structure is presented in this paper.The particle of structure is regarded as the series-parallel system, and the non-linear stiffness of the isolation layer is described as the bilinear model. Matlab software is adopted to compile the calculation program, through which, response of the eccentric structure, symmetry structure and eccentric isolated structure is analyzed with the time-process method separately, and then the dynamic response of the structures mentioned above is under comparison.This paper also presents an equivalent linearization method, which is available for random analyses and can be used to obtain the equivalent stiffness of isolation bearing. By simulating ground acceleration as filtering white noise excitation and using the equivalent stiffness, random analysis of non-linear eccentric isolated structure is performed through pseudo excitation method. The statistic characteristic of structural response is calculated to compare with that of non-isolated structures.The results of both time-process and random analysis show that the effect of eccentricity will reduce the dominant period and magnitude the dynamic response of the structure. Base isolation system can suppress the structural response as well as the torsional effect of eccentric isolated structure. Compared with symmetry structure, seismic mitigation extent of eccentric structure descends slightly.