Research On The Earthquake Response Analyses And Seismic Design Methods For Large-span Building Structures Under Multi-support Excitations

With the development of science and technology, and the elevation of economic level, building structures'design and construction technologies have developed rapidly, which results in the appearance of many large-span building structures with a span of hundreds of meters. The distance between the restraints of large-span building structures is large, and the spatial variation of ground motion results in the discrepancy of seismic excitations between different restraints (multi-support excitation effect), which causes that the seismic response of structures under multi-support excitations is quite different from that under uniform excitations. Thus study on the influence of multi-support excitation effect on large-span building structures has a great significance for the structure safety during the earthquake. Currently, research on the multi-support excitation effects is still in the exploratory stage, and neither theoretical analysis system nor design method is perfect. By using theoretical analysis and numerical calculation, this dissertation conducts a systematic research on the seismic response analyses and design methods for large-span building structures under multi-support excitations. The main work in this dissertation includes several aspects as follows:(1) The influence of displacement characteristics of ground motion power spectral density (PSD) on the seismic response of large-span building structures under multi-support excitations has been studied by using numerical method. A practical ground motion PSD model, which is based on the code response spectrum and suitable for multi-support excitation calculation, has been built.(2) Based on theoretical formula derivation, the improvement and simplification of simulation method of spatially correlated earthquake ground motions have been proposed. The consistency between the simulated ground motions and the target PSD model has been validated by numerical examples. (3) Based on theoretical analysis, the static correction method has been introduced into the absolute displacement method for multi-support excitation dynamic equation, and the modified absolute displacement method, which provides a new method for solving the multi-support excitation dynamic equation, has been proposed.(4) Based on theoretical analysis, the Pseudo Excitation Method (PEM) has been improved into a more practical form. A realizing method in the existing finite element analysis software for PEM has been proposed, which provides a simple and effective computing platform for the multi-support excitation calculation.(5) The analytic formulae of seismic response PSD of simplified large-span structure models have been derived to study the influence mechanism of multi-support excitation effects. Based on the response law derived from simplified models, the fast method of determining the most unfavorable conditions of multi-support excitation effect has been proposed for engineering design calculations.(6) The design response ratio has been proposed to evaluate the influence of multi-support excitation effects on structure response, and the evaluation system based on seismic design has been built, which provides an effective tool for the simplification of multi-support excitation seismic design that is base on the conventional uniform excitation seismic design.