Research Into The Dispersion Of Ground Motion Input Selection Based On The Simplified Model

Time history analysis method has been widely used in structure design and performance evaluation, and the uncertainty of ground motions plays a key role in elastic-plastic response of structures.Therefore, the research in the discreteness of elastic-plastic peak responses has important significance in the reasonable selection of ground motions.Carrying out the stuty on discreteness of elastic-plastic response based on simplified model and ground motions selection method. Firstly, an efficient and rapid ground motions selection method should be proposed; secondly, to reduce the cost of time in time history analysis, carrying out the research in simplified model; lastly, establishing 12 simplified models which have different periods and types, and researching the effect of the method that selecting ground motions by elastic design spectra on the discreteness of response of structures, through the research in these problems the following conclusions are obtained:(1) Using the optimization algorithm to select ground motions by matching response spectra can well control the discreteness, in addition it can decrease the time cost;(2) The elastic simplified models can well represent the real structures, therefore, we can use the result computed by the simplified models to evaluate the peak reactions of real structures in minor earthquake, and selected records satisfy the code and decrease the time cost by using the simplified models;(3) Whether the elastic and elastic-plastic model, the difference of model types have no influence on the discreteness of peak response, and the difference of periods have some influence on elastic model but small influence on elastic-plastic model;(4) To evaluate the peak response about force and drift of structures in rare earthquakes, using the elastic spectra to select 7 records based on reasonable period regions and calculating the mean values can reduce the discreteness.