基于性能抗震设计的钢筋混凝土桥墩变形能力公式推导及应用

Derivation and Application of Distortion Ability Formula for Performance-based Seismic Design Method of RC Bridge Piers

从Mander等人给出的约束混凝土应力——应变本构关系出发,根据实际应用情况进行适当地简化、推导,得出了矩形、圆形截面桥墩力学配箍率与桥墩轴压比、塑性铰的曲率延性系数及构件截面等因素的关系表达式,即变形能力公式。将该公式与25组试验数据、已有的相关研究成果及规范进行对比,证明了该公式的正确性及应用该公式得到的横向配筋水平。为方便应用,将桥墩的变形能力公式进行变换,得到了力学配箍率与桥墩的顶点位移延性系数、破损指标等因素的关系表达式,在此基础上,提出了基于性能的钢筋混凝土桥墩的设计方法,并给出应用该方法的工程实例分析过程,其结果在平均意义上与非线性时程分析结果吻合较好,进一步验证了公式的合理性。

The restraint concrete stress-strain relation which from Mander et al was used through a series of proper reduction and derivation based on practical application, the distortion ability formulas of bridge piers with rectangular or circular section were expressed by the mechanical stirrup ratio, the axis-pressure ratio, the curvature ductility coefficient and the bridge pier area ratio, etc. Comparing the outcomes from the presented formulas to 25 groups of data from test, the correlation research outcomes and the requirement of specifications, the result indicates that the correctness of distortion ability formula and the stirrup level that get by this formula. In order to facilitate the practical application, the transformation of this formula which expresses the relationship of the mechanical stirrup ratio with displacement ductility coefficient of bridge pier top and damage index was got. On this basis, performance-based seismic design method for RC bridge pier was proposed and a project example analysis was given. The result tallies well in the average meaning with the result of non-linear time history analysis, which confirmed the rationality of this formula further.