钢筋混凝土桥墩基于位移的抗震设计方法

通过改进能力谱法,给出了一个可以实现“小震不坏、中震可修和大震不倒”多级性能目标的钢筋混凝土桥墩直接基于位移的抗震设计方法。首先以钢筋和混凝土的应变幅值建立了钢筋混凝土桥墩不同破损极限状态的量化准则,并基于曲率延性系数和位移延性系数关系转化为墩顶位移的表述形式。再以屈服位移和位移延性系数作为设计参考变量,采用屈服谱加速度和屈服位移(Ay-Dy)格式的地震需求谱求解系统在不同风险水平地震作用下的反应。最后以能力设计原理保证桥墩截面的抗剪强度需求。通过一个具体设计算例说明了建议方法的可行性。

Displacement-based seismic design method of RC bridge piers

A direct displacement-based seismic design procedure of RC bridge piers fulfilling multiple performance objectives,which usually require that the structure can sustain a minor earthquake without any damage,a moderate earthquake with repairable structural damage,and a strong earthquake without collapsing,is developed by means of the improved capacity spectrum method.The procedure uses the yield displacement and displacement ductility factor as the design parameters and uses the inelastic seismic demand spectrum with yield spectral accelerations and yield displacements format to calculate the seismic demands of the pier under different earthquake levels.Seismic capacities of the pier are determined by acceptable structural damages,which are estimated quantitatively by using both the strains of concrete and the longitudinal steels in plastic hinge zones,and expressed as displacements at top of the pier by transforming from the relationship between curvature ductility factor and displacement ductility factor.The shear strength of the pier is also checked using the concept of capacity design in order to avoid brittle shear failure.The feasibility of the proposed method is validated by using an example on the seismic design of a single bridge pier.