近场地震作用下钢筋混凝土桥墩基于位移的抗震设计

用387条近场地震记录通过回归分析得到了强度折减系数, 计算了与美国UBC97规范动力放大系数谱相容的弹性位移设计谱, 并建立了相应的基于结构破坏性能的非弹性位移设计谱。探讨了钢筋混凝土墩柱基于割线刚度法的迭代设计过程和改进的不需要迭代且能实现期望设计目标延性的基于非线性位移设计谱的两种抗震设计方法, 对这两种基于不同设计谱方法的设计结果进行了比较并用非线性时程分析进行验算, 结果表明本文提出的在近场地震作用下钢筋混凝土桥墩以位移为基础抗震设计方法的有效性。

DISPLACEMENT-BASED SEISMIC DESIGN FOR RC BRIDGE COLUMNS UNDER NEAR-FAULT EARTHQUAKES

The elastic displacement design spectrum compatible with the spectrum of dynamical amplification factor in the UBC97 code is calculated, and using the strength-reduction factor obtained from the regression analysis of 387 near-fault earthquake records, the non-linear displacement design spectrum based on structural damage performance is also establisked.The iterative displacement-based seismic design procedure of secant stiffness method and the improved seismic design method based on the non-linear displacement design spectra for reinforced concrete columns are discussed,the latter needs no iteration in the design procedure and the design objective ductility can be directly realized.The design results using these two methods are compared and verified by using nonlinear dynamic time-history analysis. The analysis result shows that the displacement-based seismic design method presented in this paper for RC bridge columns under near-fault earthquakes is effective.