Research On Elastic-plastic Displacement Spectra And Its Application In Seismic Design Of Structrues

Due to the displacement can reflect the performance of the structure underearthquakes better than strength, the direct displacement-based seismic design usesthe displacement of the structure as a target parameter to design the structure in thebeginning, with the result that it can effectively control the behaviors of the structureunder the action of earthquake. Compared with other methods, direct displacement-based seismic design can explicitly demonstrate the conception of performent-basedseismic design. To calculate the elastic-plastic displacement response of the structureunder the action of earthquakes exactly is the first step in achieving the performent-based design.The elastic-plastic displacement response spectra of single-degree-of-freedomsystem was calculated in this thesis, then the elastic displacement spectra was appliedto seismic design of structure, the major researches in this thesis are as followes:The influence factor of magnitude and fault distance on elastic displacementresponse spectra is analyzed in this thesis. By means of regression analysis, theformula of elastic displacement spectra is established, which can be applied to ahigher damping ratio(30%) and response periods up to10s, And the formula,including magnitude, fault distance and site class as basic variables, can calculate theconditions of displacement spectra with magnitude between4.7to7.6, and faultdistance up to120km. The results obtained from the formula show that start period ofthe plateau of displacement spectra depend on magnitude, the results also exemplifythat magnitude exert a considerable influence on scaling factor.The influence of site class and ductility on constant-ductility displacement ratiosspectra, and the influence of site class and strength reduction factor on constant-strength displacement ratios spectra are discussed in this thesis, Owing to regressionanalysis, the formula of constant-ductility displacement ratios spectra and constant-strength displacement ratios spectra is established. Then the influence of site classand design characteristic period on R-μ-T relations is also analyzed, On the result ofregression analysis, the formula of constant-strength ductility demand spectra as wellas constant-ductility strength spectra is established, which site class and designcharacteristic period are considered.This thesis firstly introduces the basic principle of direct displacement-based seismic design，then the design procedures of direct displacement-based seismicdesign for reinforced concrete frame are illustrated in detail. In order to compare withthe design method according to current seismic codes, a8-story frame structuraldesign with direct displacement-based seismic design method is constructed.