基于保险丝理念的摇摆-自复位双层桥梁排架墩抗震设计理论

Urban traffic jams have become more and more serious, and the double deck viaducts with double layer bridge bents as columns are promising in urban traffic system. By combining the construction advantage of the precast structure and good seismic behavior of the rocking self-centering structure, an innovative rocking self-centering double layer bridge bent will be proposed. And the seismic design theory for the bents based on structural fuse concept will be developed by using replaceable angels. During severe earthquakes, the seismic damage will be concentrated in the angles while the damage to the concrete bents will be limited. The damaged angles could be replaced and the behavior of the bents could be restored rapidly. First, an innovative double layer bridge bent will be proposed, the seismic damage control effect and restorability of the bent will be investigated by unidirectional and bidirectional quasi-static tests. Then, the seismic behavior of the bents will be evaluated by bidirectional shaking table tests. The spatial seismic analysis model for the bent will be proposed and the seismic damage process and damage mechanism of the bent will be studied by dynamic time history analysis. At last, the seismic design theory based on structural fuse concept will be developed for the double layer bridge bent. The finding of the project will be useful for accelerating construction of the viaduct and for seismic safety of the traffic lifeline system, and the seismic design theory for bridges will be improved.

城市交通拥堵问题日益严重，以双层排架墩作为主要受力体系的高架桥梁在城市交通建设中具有广泛应用前景。本课题利用预制－拼装结构的施工优势和摇摆－自复位结构的抗震优点，结合外置可替换耗能角钢，提出新型摇摆－自复位双层排架墩并发展其基于保险丝理念的抗震设计理论。强震下，地震破坏集中于可替换耗能角钢而排架墩本身免于地震损伤，且震后损坏的耗能角钢易于替换并迅速恢复原结构的使用功能。首先提出双层排架墩体系并基于单向及双向加载拟静力试验揭示其地震损伤控制效果和震后功能的可恢复性；在此基础上完成摇摆－自复位双层排架墩双向振动台试验并验证其抗震能力的可靠性。建立新型双层排架墩地震响应空间数值分析模型，通过动力时程分析揭示排架墩的地震损伤破坏过程及破坏机理，最终发展新型双层排架墩基于保险丝理念的抗震设计方法。课题对加快城市高架桥梁建设、保证交通生命线抗震安全具有重要意义，并推动桥梁抗震设计理论的发展。

国家自然科学基金“基于保险丝理念的摇摆-自复位双层桥梁排架墩抗震设计理论(51678150)”双层桥梁排架墩为研究对象，通过试验研究以及数值分析等手段，揭示了此类结构的地震损伤破坏机理，发展了此类结构的分析手段和设计理论，具体为：.(1) 基于耗能角钢、不锈钢筋、工程水泥基复合材料(Engineered Cementitious Composites, ECC)等提出了新型摇摆-自复位单层及多层排架墩，提出了摇摆-自复位桥墩抗震性能的精细化数值建模方法并通过与试验结果的对比进行了验证。.(2) 通过数值分析手段，分析了实际地震动输入下摇摆-自复位单柱墩、单层排架墩、双层排架墩的地震反应。结果表明，摇摆-自复位桥墩侧向初始刚度减少，自振周期增大；震后几乎无残余位移，便于桥墩的震后功能恢复。.(3) 完成了摇摆-自复位桥墩抗震拟静力试验，揭示了此类结构在减轻结构地震损伤破坏中的特殊优势。.(4) 完成了配置ECC的钢筋混凝土梁板构件耐久性试验及抗弯试验，验证了此类结构用于摇摆-自复位桥墩接缝位置的优势。.(5) 完成了不锈钢筋本构模型试验及数值建模方法研究，验证了此类结构用于摇摆-自复位桥墩接缝位置耗能钢筋时的耗能能力。.(6) 建立了考虑桩-土-结构相互作用(pile-soil-structure interaction, PSSI)的桩柱式桥墩抗震数值分析模型，讨论了墩顶残余变形的机理。.(7) 提出了双层摇摆-自复位桥梁排架墩地震损伤控制设计方法及构造细节。发展了钢筋混凝土桥墩地震损伤破坏分析方法。