Study Of Seismic Response On The High-soft Structure Under Coupled Horizontal And Tilt Ground Motion

The ground motion consists of three translational components and three rotational components. In previous studies, the researchers always ignored the tilt ground motion. In fact, the tilt ground motion will cause a significant seismic effect on the building structure. When the structure is under the coupled translational and tilt(CTT) ground motion, tilt ground motion will increase the dynamic effect on high-flexible structure, and the tilt angle time history will cause foundation tilt which magnifies the P- ? effect, especially for the structure system with high height, weak lateral stiffness. It will result in serious consequences when the tilt ground motion is ignored. Therefore, it is necessary to make research on high-flexible structure under multidimensional ground motion.Tests and theoretical analysis for high-flexible structure under coupled horizontal and tilt ground motion were conducted to discuss the effect of tilt ground motion, especially the seismic effect of high-rise structure caused by tilt displacement.The main contents are as follows:1) The method of obtaining tilt ground motion based on wavelet analysis theory. The rotational components of earthquake ground motion results from the tilt of faults which has a remarkable impact on the horizontal acceleration recorded by seismograph, and establish the rotational components of earthquake ground motion collecting method based on wavelet transform theory and threshold process. Using this method to obtain tilt ground motion, and verify the veracity and accuracy of earthquake ground motion collecting method based on wavelet transform theory by shaking table experiment.2) The nonlinear dynamic equation. Then the nonlinear dynamic equation was developed, in which the asymmetrical P- ? effect caused by the foundation tilt was considered as an equivalent horizontal lateral force playing a part of the excitation item in the equation.3) Tests and theoretical analysis for high-flexible structure. The shaking table test under horizontal, tilt and CTT ground motion was carried out on the scaled model of a high-flexible structure taking a television tower as prototype, whose results were also compared with the theoretical analysis, discussing the seismic effect by tilt displacement.The results illustrate that,1) The residual tilt displacement of of earthquake ground motion, which is obtained with the method based on wavelet transform theory, is consistent with the actual displacement and low-frequency part of the horizontal Fourier spectrum with of earthquake ground motion being filtered is similar to the vertical one. Shaking table tests verify the veracity of of earthquake ground motion collecting method based on the theory of wavelet transform, and compared to the Fourier transform method, the result is better consistent with the actual situation with greatly improved accuracy;2) The shaking table test results basically coincides with the developed theoretical analysis considering the foundation tilt;3) The additional P- ? effect caused by the foundation tilt not only enlarges the seismic response of high-flexible structure, but also leads to a remarkable asymmetrical displacement effect, resulting in a great increase on the structural horizontal displacement. And in consequence, the effect should be attached importance through the practical seismic design and computation process.