设计用地震动总输入能量谱研究

地震动总输入能量的确定是基于能量的设计方法首先要解决的关键问题。本文以单自由度弹性系统为研究对象,分析了地震动三要素和结构自身参数对输入能量谱因素的影响。结果表明,地震动幅值、频谱特性和强震持时都对能量谱值有较大影响,其中频谱特性还影响能量谱峰值出现的结构周期段;结构阻尼比的增大能有效降低能量谱峰值。通过输入160条国内外历次地震中不同场地上的地震动记录,总结能量谱曲线形状规律,提出了设计用三段式简化能量谱曲线。给出了地震动记录所属场地类型的划分标准,建议了确定能量谱峰值的不同场地条件地震动频谱特性V/A和强震持时tD的取值,采用标准化方法提出了4类场地条件的设计用能量谱曲线峰值及其它参数的计算式,给出了结构设计总输入能量计算过程。算例分析结果表明,该输入能量谱形式简单、计算方便,结果安全可靠。

Research on Input Energy Spectra for Design of Earthquake Strong Motion

Determination of energy demand to structure needs to be solved firstly in energy-based method.Influence of ground motion characteristics and structure parameters on input energy spectra is studied for elastic single degree of freedom system.The result indicates peak ground motion,characteristics of spectrum,have much influence on the spectra.Furthermore,characteristics of spectrum determines the structure period which correspond to peak value of input energy spectrum.Peak value of input energy spectrum decreases obviously with damping ratio increase.Based on a total of 160 ground motion records from many significant earthquakes in different countries,three parts simple function is suggested according to the shapes of spectra.Classification of earthquake motion to different sites and characteristics of spectrum V/A and effective duration t_D for different sites are advised.By normalized input energy spectrum method,expressions of input energy spectra for different sites are suggested and energy demand is determined.Results show input energy spectra for energy-based seismic design which has simple format is convenient for calculation and reliable for application.