基于Kiewitt-8型单层球面网壳的一维地震动强度参数研究

选择合适的地震动强度参数可降低与结构响应相关分析结果的离散性，为得到较为合适的描述Kiewitt-8型单层球面网壳地震响应的地震动强度参数，对常用地震动强度参数的考虑因素进行分析，按是否考虑结构动力特性将其分为地震动绝对强度和地震动相对强度（基本模态的加速度反应谱值）S_a(T₁)；对Kiewitt-8型单层球面网壳分别进行大量的水平一维和竖向一维地震时程响应分析，计算地震动强度参数与结构响应的相关系数。结果表明：地震动相对强度参数在水平方向上与地震动绝对强度参数相比能较好反映地震作用对结构的影响，但在竖向存在局限，与结构响应不具有较好的相关性。此外，控制结构最大竖向响应振动模态的振动周期通常是未知的。通过对S_a(T₁) 局限产生的原因进行分析，提出了一种可用于工程的地震动相对强度参数即敏感频率反应谱值S_a (f_p)，该参数在水平向和竖向表现出了更好的与结构响应的相关性。

Study on one-dimensional earthquake intensities for Kiewitt-8 single-layer reticulated domes

Selection of an appropriate ground motion intensity measure to be used in scaling or standardizing the ground motion records is of importance as it can be used to reduce the scatter of the obtained peak responses for different ground motion records. To identify such an adequate ground motion intensity measure for Kiewitt-8 single-layer reticulated domes, it was noted that the ground motion intensity measure could be grouped as absolute intensity and relative intensity, by considering whether the dynamic characteristics of structures were taken into account. Based on the statistics of peak displacements obtained from the time history analyses that were carried out for Kiewitt-8 single-layer reticulated dome under horizontal or vertical ground motion components of selected records, the correlation coefficients between the peak displacements of the structure and a group of selected ground motion intensity measures, including the spectral acceleration response at the fundamental vibration period,S_a(T₁), were evaluated. The results show thatS_a(T₁) is an adequate ground motion intensity measure for the horizontal excitations for the considered dome. However, its use for vertical response is questionable as expected. Furthermore, the vibration period mode that controls the peak vertical displacements is usually unknown. A simple practical approach to remediate this drawback is suggested. It requires the use of harmonic analysis for horizontal and vertical excitations to identify the vibration periods at which the structure reaches its peak responses. The spectral acceleration values at the identified periods can then be used as ground motion intensity measure.