基于条带－云图法的地震动持时对结构 地震易损性影响分析

Ground motion duration has significant influence on the damage of structures. Nevertheless, the impact of ground motion duration was rarely considered in seismic fragility analysis of structures currently. In this paper, the stripe-cloud approach was proposed to investigate the influence of ground motion duration on seismic fragility of structures. Vector-valued intensity measure (IM) of ground motion, IM =[IM₁, IM_2], was introduced. First, IM₁ is used to perform time-history analysis of structures based on stripe method, and IM₂ which relates to ground motion duration is used to discretize the statistical results of the time-history analysis. Then cloud method is adopted further to establish the probabilistic seismic demand models for structures which can consider the influence of ground motion duration reasonably. Furthermore, two suites of ground motion records with long- and short-duration were chosen as inputs respectively, and stripe-cloud approach was conducted for 3 reinforced concrete frame structures which have varying heights. The results demonstrate that stripe-cloud approach not only dramatically increases the correlation between seismic intensity measures and structural damage measures, but also improves the reliability of the probabilistic seismic demand models of structures. Vector-valued IM can effectively consider the effect of duration on seismic fragility analysis. Long-duration ground motion can cause severer damage at lower intensity levels comparing to short-duration ground motion. It is necessary to explicitly consider the effect of ground motion duration in seismic fragility analysis. The influence of ground motion duration on the seismic fragility analysis results is also related to the IM selected. Energy-related IMs can consider the influence of duration appropriately.