Attenuation power index and damping reduction factor of seismic design spectrum for long-period ground motions

作者：Zhou, Jing; Fang, Xiaodan^*; Mao, Wei

来源：Journal of Building Structures, 2017, 38(1): 62-75.

DOI：10.14006/j.jzjgxb.2017.01.007

• Acceleration spectrum
• Damping reduction factors
• Dynamic amplification factors
• Long-period ground motions
• Power indices
• Response spectra

The difference between absolute-acceleration response spectrum (ARS) based on the earthquake inertia force and quasi-acceleration response spectrum (QRS) based on the hysteretic restoring force of the structure were explained, and the variation rule of the attenuation power index and the damping reduction factor of the QRS for long-period ground motions were studied. The digital ground motion records with rich long-period components from destructive shallow earthquake were selected, and the elastic response spectrum analysis method was employed to calculate the characteristic period, the attenuation power indexes of curvilinear decrease sections and the damping reduction factor of the dynamic amplification factor spectrum based on the QRS. The results show that the seismic design spectrum based on the bearing capacity should suitably be calibrated by the QRS based on the hysteretic restoring force of the structure, and the design spectrum calibrated by the ARS based on the earthquake inertia force might lead to rather conservative seismic design for the long-period structures with high damping ratio. The attenuation trend of curvilinear long-period section of the ARS is different from that of the QRS which attenuates comparatively fast for the structures with high damping ratio. It is rational and feasible for the standard seismic design spectrum based on the QRS with 5% damping ratio to adopt the simple attenuation rule in the first and second decrease section, namely 1/T and 1/T2, respectively, and also the QRS with high damping ratio can be obtained and does not need to reduce the attenuation power index. The dynamic amplification factor of the long-period seismic response spectrum has significant site effects, and it is well suitable for the site class I, site class II, site class III and site class IV to use 0.9, 1.0, 1.1 and 1.2, respectively, serving as the site effect factors and referring to the site class II level. The long-period components of ground motions have a great influence on the damping reduction factors, and the damping reduction factors based on the QRS are significantly different from the damping reduction factors based on the ARS in the long-period section. Numerical engineering example validates the rationality of attenuation power index and damping reduction factor of the proposed design spectrum for long-period structures.

• 出版日期2017-1-1
• 单位华南理工大学