地震动持时对砌体结构地震响应影响研究

Study on Influence of Ground Motion Duration on Seismic Response of Masonry Structures

摘要:

作为地震动的三要素之一，地震动持时会显著影响结构的地震响应与损伤状态。为研究地震动持时对砌体结构地震响应的影响，通过谱匹配方法和小波变换消除频谱和幅值影响，以抗震设计谱为目标谱匹配得到 100 条不同持时的地震动记录，同时通过等效框架法建立一个典型砌体结构数值模型，随后将得到的 100 条地震动记录输入到数值模型开展地震反应分析，根据分析结果探讨地震动持时对砌体结构最大层间位移角、滞回耗能及累积损伤的影响，并通过回归分析得到了地震动持时对砌体结构地震响应参数影响的经验公式。结果表明：长持时地震会比短持时地震对砌体结构造成更大的损伤破坏；砌体结构地震响应参数与持时的相关性从高到低依次为滞回耗能、软化损伤指数、Park?Ang 损伤指数、最大层间位移角；砌体结构最大层间位移角、滞回耗能以及 Park?Ang 损伤指数均随地震动持时的增大呈增长趋势，但持时较短时增长速度较慢，随着持时的增大，增长速度有所加快，但不同的是滞回耗能最终又会趋于平稳；砌体结构软化损伤指数随地震动持时的增大呈增长趋势，但持时较短时增长较快，随着持时的增大，软化损伤指数逐渐趋于平稳；以文中选取的长、短持时地震动为例，长持时地震动作用下的 Park?Ang 损伤指数、滞回耗能、软化损伤指数和最大层间位移角分别是短持时地震动作用下的 4.5 倍、10 倍、2.32 倍、2.99 倍。结果可供砌体结构抗震设计和地震损伤评估参考。

Abstract:

As one of the three essential elements of ground motion, ground motion duration significantly affects the seismic response and damage state of structures. To investigate the influence of ground motion duration on the seismic response of masonry structures, spectral matching methods and wavelet transforms were employed to eliminate the effects of spectrum and amplitude. 100 ground motion records with different durations were obtained by matching them to the target spectrum based on the seismic design spectrum. Additionally, a numerical model of a typical masonry structure was established using the equivalent frame method, and the 100 seismic records were input into the numerical model to conduct seismic response analysis. Based on the analysis results, the influence of ground motion duration on the maximum inter-story drift angle, hysteretic energy dissipation, and cumulative damage of masonry structures was examined. Empirical formulas for the influence of ground motion duration on the seismic response parameters of masonry structures were derived through regression analysis. The results showed that long-duration earthquakes caused greater damage to masonry structures compared to short-duration earthquakes. The correlation between seismic response parameters of masonry structures and duration, ranked from highest to lowest, was as follows: hysteretic energy dissipation, softening damage index, Park-Ang damage index, and maximum inter-story drift angle. The maximum inter-story drift angle, hysteretic energy dissipation, and Park-Ang damage index of masonry structures all increased with the extension of ground motion duration. However, when the duration was short, the growth rate was relatively slow. As the duration increased, the growth rate accelerated, but hysteretic energy dissipation eventually tended to stabilize. The softening damage index of masonry structures increased with longer ground motion durations. When the duration was relatively short, it grew rapidly, but as the duration further increased, the softening damage index gradually stabilized. Taking the long- and short-duration ground motions selected in this study as examples, the Park-Ang damage index, hysteretic energy dissipation, softening damage index, and maximum interstory drift angle under long-duration ground motion were 4.5 times, 10 times, 2.32 times, and 2.99 times those under short-duration ground motion, respectively. The findings of this study can serve as a reference for seismic design and earthquake damage assessment of masonry structures.