不同场地类别减震性能曲线研究

Dampingperformance curves for different site types seismic waves

根据不同场地类别建立减震性能曲线克服了地震波减震性能曲线存在差异的问题,对减震结构的简化设计与分析具有重要意义。在单质点体系简谐激励下,以位移减震率η_(d)与加速度减震率η_(a)解析表达式为基础,以特征周期为依据对大量地震波进行场地分类,并对所有不同场地类型地震波进行时程分析,作出可用于各类场地地震波的减震性能曲线,考虑了场地特征周期对减震性能曲线的影响,从而确定用于计算弹性时程下减震结构的位移与加速度减震率拟合公式;在此基础上又建立了考虑结构非线性状态减震性能曲线,曲线表明增加阻尼比虽然能降低结构的塑性率,但降低效果有限,且塑性率越大,增加阻尼比的减震效果越不明显。该研究扩展了减震性能曲线的应用范围,为减震结构的性能化设计提供了重要依据。

Establishing damping performance curves according to different site types seismic waves solves the problem of differences in seismic wave damping performance curves,it is of great significance to simplified design and analysis of shock absorbing structures.Here,under simple harmonic excitation of single mass point system,based on analytical expressions of the displacement damping rateη_(d) and acceleration damping rateη_(a),the site classification for a large number of seismic waves was performed according to their characteristic periods,and time-history analyses for all different site types seismic waves were done to obtain damping performance curves applicable forvarious site types seismic waves.Considering effects of site characteristic period on damping performance curve,fitting formulasforcalculating displacement and acceleration damping rates under elastic time-histories were determined.Then,damping performance curves considering nonlinear states of structure were established.Curvesshowed that although increasing damping rate can reduce the plasticity rate of structure,the reduction effect is limited,and the larger the plasticity rate,the less obvious the damping effect of increasing damping rate;the study can expand the application range of damping performance curves and provide an important basis for performance-based design of shock absorbing structures.