地震动广义动力放大系数谱及其特性研究

传统地震动力放大系数谱是根据地震动最大加速度和结构最大加速度而确定的,没有充分虑及时域非平稳性。通过比较不同周期结构最大反应出现时刻和地震动峰值出现时刻,验证极大峰值对结构反应同样有重要的作用。提出考虑若干极大峰值作用的等效动力放大系数谱的概念,计算不同场地类型下的统计谱并验证其保守性。鉴于考虑频域非平稳性的动力放大系数标准差谱的合理性,计算相关统计谱并确认其在长周期段谱值较高。综合考虑传统谱、等效谱和标准差谱的特点,基于三种谱外包络提出具有足够的保守性的广义动力放大系数谱的概念。建立广义动力放大系数谱与传统谱的比值拟合公式。通过算例验证按广义动力放大系数谱进行结构抗震设计或验算具有更高的安全性。

Generalized dynamic amplification coefficient spectrum of ground motion and its characteristics

The traditional spectrum of seismic dynamic amplification coefficient is determined according to the maximum acceleration of ground motion and that of structure not fully considering the non-stationarity in time domain.By comparing the occurring time of the maximum response of different periodic structures and that of ground motion peak values,it is verified that ground motion extreme peak values have important actions on structural response.Here,the concept of equivalent dynamic amplification coefficient spectrum considering actions of several extreme ground motion peak values was proposed.The statistical spectrum of different site types was calculated and its conservation was verified.In view of the rationality of the standard deviation spectrum of dynamic amplification coefficient considering the non-stationarity in frequency domain,the correlation statistical spectrum was calculated and its spectral values were confirmed to be higher in the long period duration.Comprehensively considering characteristics of traditional spectrum,equivalent spectrum and standard deviation spectrum,the concept of generalized dynamic amplification coefficient spectrum with sufficient conservation was proposed based on three kinds of spectral outer envelope.The fitting formula for the ratio of generalized dynamic amplification coefficient spectrum to traditional spectrum was established.Through examples,it was verified that structural aseismic design or checking calculation according to the generalized dynamic amplification coefficient spectrum has higher safety.