钢筋混凝土圆柱等效阻尼比及在桥梁抗震分析中的应用

基于对50根弯曲破坏钢筋混凝土圆柱低周反复试验结果的分析,建立了完整滞回环的数学表达式并推导得出等效阻尼比计算模型;以双柱墩桥梁为例,说明了建立桥梁整体结构等效阻尼比与墩柱端部塑性铰等效阻尼比关系的方法。研究表明,完整滞回环数学表达式较好地反映了弯曲破坏钢筋混凝土圆柱的滞回特性,得到的等效阻尼比模型计算结果与试验结果符合较好;采用建立的桥梁整体结构等效阻尼比与墩柱端部塑性铰等效阻尼比的关系进行pushover分析更能反映实际情况。采用等效阻尼比模型算得的目标位移与基于Rosenblueth模型和Kowalsky模型算得的位移之间存在较大差距。

Equivalent damping ratio of RC circular columns and its application in bridge seismic analysis

Based on analysis of the test results of 50 RC specimens of circular columns failed in flexure,an expression for defining the hysteretic loop is proposed and a model for predicting the equivalent damping ratio is developed.The procedure for associating the equivalent damping ratio of a structure as a whole with those of its element is established by an example of double-column pier-bridge.It’s indicated that the expression of hysteretic loop proposed well defines the hysteretic loops of RC columns.Rational outcome can be expected when performing pushover analysis using the relationship of equivalent damping ratio of a bridge as a whole with those of its element.The target displacement predicted with the proposed model is different from those predicted with Rosenblueth’s model and Kowalsky’model.