预制节段拼装中空夹层钢管混凝土桥墩性能化抗震设计方法研究

RESEARCH ON PERFORMANCE-BASED SEISMIC DESIGN METHOD FOR POSTTENSIONED PRECAST SEGMENTAL CFDST BRIDGE PIERS

  • 摘要: 为满足桥梁快速建造和震后功能可恢复的发展趋势,发展具有震后低损伤、自复位能力的新型预制节段拼装中空夹层钢管混凝土(CFDST)桥墩,对新型桥墩的抗震设计方法进行研究。首先,从预制节段拼装CFDST桥墩的损伤破坏机理出发,采用5个等级划分了结构的抗震性能水准。然后,基于震后可恢复理念,选取以墩顶水平位移角 \theta _\textdr 与残余位移角 \theta _\textR 作为其抗震性能指标,通过对大量拟静力试验和数值模拟结果的统计分析,确定了各抗震性能水准对应的双重量化指标。在此基础上,建立了预制节段拼装CFDST桥墩的性能化抗震设计方法。以公路常见中小跨径三跨连续梁桥为实例,采用预制节段拼装CFDST桥墩作为桥梁下部结构,进行了预制节段拼装CFDST桥墩的抗震设计与非线性时程分析检验。其非线性时程分析结果表明:墩顶最大水平位移和残余位移满足了既定要求,通过控制墩顶残余位移,提高了桥墩震后可恢复性能。

     

    Abstract: To meet the development trend of rapid bridge construction and post-earthquake functional recovery, a new type of posttensioned precast segmental concrete-filled double skin steel tubular (CFDST) bridge pier featuring low damage and self-centering capacities was developed and the seismic design method was investigated. Based on the damage and failure mechanisms of such piers, five seismic performance levels are defined. The lateral drift ratio \theta _\textdr and residual drift ratio \theta _\textR are adopted as key design indicators in line with the concept of seismic resilience. The quantified relationship between the performance levels and indexes are established through cyclic lateral loading tests and through numerical analysis results. A performance-based seismic design method is proposed, and detailed design procedures are illustrated with representative examples. The method is validated via nonlinear time-history analyses. Research results demonstrate that the posttensioned precast segmental CFDST bridge pier meets the prescribed seismic performance levels in terms of both maximum and residual displacement responses. Moreover, controlling the residual drift ratio during the design process significantly enhances the seismic resilience of the bridge pier.

     

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