【摘要】 地震动持续时间是地震动特性的三要素之一(幅值、频谱特性、持时),对结构的累积破坏有着重要的影响。文中利用能考虑混凝土软化特性并可反映实际损伤耗散的混凝土塑性损伤本构模型,采用时域分析方法对不同持时特征的强震作用下大坝损伤累积破坏效应进行了计算分析,根据大坝损伤开裂发展特征,建立大坝局部和整体损伤累积破坏指标,比较强震持时对大坝损伤累积破坏的影响。分析结果表明:地震动强震持时特征对大坝损伤累积破坏范围有着显著的影响,长持时地震动作用将导致较大的损伤累积破坏,在大坝抗震设计中应给予重视;大坝抗震薄弱部位主要位于坝体中上部,采用局部累积损伤破坏指标可以有效地判定大坝抗震薄弱部位,提出的大坝整体损伤累积破坏指标可以综合评价大坝整体损伤累积破坏程度,有效地评价大坝抗震性能。更多还原

【Abstract】 Ground motion duration is one of the three key elements——amplitude,spectral characteristics and duration of ground motion that significantly affect the accumulated damage of dam structures.In this paper,a damage mechanics model is put forth for simulation of the damage dissipation of concrete fracturing and the effects of strain softness after post-peak,and overall and local indices of accumulated damage for cracking damage development are established to compare the influence of different durations on the accumulated damage.The analysis reveals that strong motion duration has a significant impact on the accumulated damage and that longer duration leads to greater damage,which should draw great attention in aseismic design.Application of the local index that is an effective criterion for the weak parts of a dam,shows that the weakness of dam structure under seismic loading is concentrated on its upper part.Thus,the proposed model provides an effective tool for quantitative evaluation of the damage level of gravity dams under strong earthquakes and also for evaluation of seismic performances of gravity dams.更多还原