Seismic behavior prediction and post-earthquake performance evaluation of bridge superstructures

1995年科比地震的报告表明，梁端的冲击破坏和支架的失效会阻碍救援工作的进行。为了准确分析桥梁碰撞行为和评估碰撞缓解措施的有效性，建立了包括碰撞和碰撞缓解装置的全桥结构三维模型。特别是桥梁在地震作用下的脱空对桥梁的安全性和使用性能有很大的危害。近年来的大震研究表明，碰撞不仅会导致桥梁沿着纵向的破坏，还会引起桥梁的横向位移和转动，从而导致桥梁的脱空。此外，为了精确分析碰撞效应，还需要对整个桥梁结构进行三维建模。提出了一种考虑摩擦的桥梁三维碰撞问题的模型。通过碰撞试验验证了该模型的正确性。全桥结构的三维非线性模型也被采用。编制了桥梁动力分析通用程序，并对一座三跨钢桥进行了碰撞计算。结果表明了碰撞模型的适用性。然后，在研究的后半部分，选择了三跨钢结构高架桥作为研究对象。此外，梁之间的峰值间隙尺寸和最大相对位移的支持被用于评估的可用性。

A report of 1995 Kobe earthquake showed that impact damage at ends of girders and fails of supports can impede traffics of rescue works. To precisely analyze the behaviors of bridges with poundings and evaluate the effectiveness of pounding mitigation measures, a 3D model for whole bridge structures including pounding and pounding mitigation devices is constructed. Especially, unseating of bridge girders/decks during earthquakes is very harmful to the safety and serviceability of bridges. Evidence from recent severe earthquakes indicates that in addition to damage along longitudinal direction, lateral displacement and rotation of bridge girders caused by pounding can also lead to unseating.To analyze this effect, a 3D model of pounding is constructed at the first half of the research. In addition, for a precise analysis of pounding effects, 3D modeling of whole bridge structures is also in demand. This research presents a model for 3D pounding problems of bridge girders with friction. Experiments of pounding were conducted to verify this model. 3D nonlinear models of whole bridge structures have also been adopted. A general-purpose dynamic analysis program for bridges and conducts computations of pounding among a three-span steel bridge has been implemented. The applicability of the pounding model is illustrated with the results. Then, at the last half of the research, three-span steel elevated bridge has been chosen for a case study. In addition, the peak gap size between girders and maximum relative displacements of supporters are employed for serviceability evaluation.