跨海大桥节段拼装桥墩的抗震设计

节段拼装桥墩是适应新的桥梁施工方法的新型结构体系,具有施工进度快、环境冲击少、施工质量高等优点。以矩形空心截面节段拼装高墩为例,利用纤维梁-柱单元建立桥墩的有限元模型,通过与已有拟静力试验结果的对比,验证模拟方法的正确性。在节段拼装桥墩的优化设计中,将水平承载力分析与理论模型的预测结果加以比较,并分析桥墩的地震时程响应。试验模拟结果表明,拼装桥墩的节段接缝处的耗能钢筋可以增强桥墩的水平承载力,显著提高其耗能、增大残余位移;提高预应力钢筋的配筋率虽能增强桥墩的水平承载力,但对能量耗散和残余位移影响不大;预应力筋有黏结时比无黏结时的水平承载力提高约30%,有黏结时的残余位移约为无黏结时的2倍。桥墩的地震时程响应分析结果表明,增加耗能钢筋可以提高桥墩的水平承载能力、减小桥墩顶部的最大位移、延缓桥墩的破坏过程。

Earthquake Resistant Design for Cross-sea Bridge Segmental Assembly Abutments

As a new structural system, the segmental assembly abutments are adopted to adapt to new bridge construction technologies, which can shorten construction period, minimize environmental impact and improve construction quality etc. Rectangular hollow section segmental assembly high-abutment is taken as an example, in which fiber beam-column element is used to create bridge abutment finite element model, and the simulation method is validated by comparing with the static test simulated result. In the design optimization of segmental assembly abutments, lateral bearing capacity analysis is compared with theoretical model prediction result, and seismic time-history response analysis of bridge abutments is made too. The simulation test result shows that the lateral bearing capacity, energy dissipating capability, and residual displacement of bridge abutments can be greatly enhanced by adding energy dissipating reinforcement at segmental joints. High ratio of pre-stressed reinforcement enhances lateral bearing capacity of abutments, but has little effect on residual displacement and energy dissipation. The lateral bearing capacity is increased by 30 % when pre-stressed reinforcement are adhering each other, the adhesive residual displacement is 2 times as much as non-adhesive one. The seismic time-history response analysis shows that more energy dissipating reinforcement increases the lateral bearing capacity decreases the maximum displacement at the top of abutments and extends the service life of abutments.