摇摆式预应力混凝土桥墩基于位移的抗震设计方法研究

摘要

Based on performance-based aseismic design idea,a displacement-based aseismic design method for rocking bridge piers with post-tensioning tendons was developed.With this design method,the level of piers damage was determined on the basis of anti-earthquake fortification level;the target displacement of piers was estimated considering the effect of deformation of the interface region of piers bottom;with inelastic response spectrum,the displacement demand under earthquakes was calculated.Energy dissipation bars or additional external dissipation devices deployed in the piers-to-foundation critical interface region were used to dissipate earthquake energy.Unbonded post-tensioning tendons were used to provide the shear-resistance through the friction developed at the pier-to-foundation interface,the initial tension of tendons was designed reasonablly to maintain stress of tendons in the elastic range,and negligible residual displacements of piers were expected.The reliability of this design method was assessed by comparing it with the existing design approaches.The study results showed that compared with the existing design methods,the proposed design approach gives results being more consistent with those of the nonlinear time-history analysis.%根据基于性能抗震设计的思想，提出一种摇摆式预应力混凝土桥墩基于位移的抗震设计方法。该方法根据桥梁抗震设防水准确定桥墩的损伤水平，并考虑墩底接缝区变形的影响计算桥墩的目标位移；借助非弹性位移谱计算桥墩的位移需求。摇摆式预应力混凝土桥墩在墩底接缝区设置耗能钢筋或外部耗能装置来耗能地震能量，利用无粘结后张拉钢束在接缝处产生的摩擦力提供剪切抗力，合理设计预应力钢束的初张力，使其在地震荷载作用下保持在弹性范围内，保证其良好的复位能力。通过与已有的设计方法相比，评估了所提出的设计方法的可靠性。研究结果表明：与已有的设计方法相比，用所提出的摇摆式预应力混凝土桥墩基于位移的抗震设计方法的设计结果与非线性时程分析结果的相关性更好。