预制节段拼装中空夹层钢管混凝土桥墩自复位与耗能能力计算方法研究

CALCULATION METHOD ON SELF-CENTERING AND ENERGY DISSIPATION CAPACITIES OF POSTTENSIONED PRECAST SEGMENTAL CIRCULAR CFDST PIERS

  • 摘要: 新型预制节段拼装中空夹层钢管混凝土桥墩结合预制节段拼装桥墩和中空夹层钢管混凝土构件的受力特点,具有良好自复位能力和快速施工优势,符合震后可恢复桥梁的发展趋势,然而如何平衡该新型桥墩的自复位与耗能能力,保证其震后功能可恢复性是工程设计中亟需解决的关键问题。本文首先基于该新型桥墩的工作机理,提出了采用耗能系数\lambda _\textED衡量桥墩恒载轴压比、初始预应力轴压比和耗能钢筋配筋率等参数对其自复位与耗能能力的影响;其次采用OpenSees软件建立了该新型桥墩拟静力试验的数值分析模型,并基于试验结果验证了模型的正确性;最后研究了残余位移角\theta _\textR和等效粘滞阻尼比\xi _\texteq关于耗能系数\lambda _\textED的关系,通过回归分析建立了\theta _\textR和\xi _\texteq关于\lambda _\textED的计算公式,并基于已有试验验证了公式的合理性,从而建立了该新型桥墩自复位与耗能能力的计算方法,可用于指导其自复位与耗能能力设计。

     

    Abstract: The new posttensioned precast segmental circular concrete-filled double skin steel tubular (CFDST) bridge pier combines the advantages of posttensioned precast segmental pier and composite CFDST member, in such a way to improve bridge resilience and accelerate bridge construction. It aligns with the development trend of seismic resilient bridge. However, balancing the self-centering and energy dissipation capacities of this new bridge pier to ensure its seismic resilience is a critical issue that needs to be addressed in engineering design. Based on the rocking mechanism of the new bridge pier, an energy dissipation factor \lambda _\textED is adopted to represent the influence of the amount of ED bars, the axial load ratio due to dead load and the initial prestressing force on the self-centering and energy dissipation capacities. A finite element model is developed to simulate the seismic performance and is verified by the results of cyclic loading test. Finally, a parametric analysis is conducted to investigate the influence of this factor on the self-centering and energy dissipation capacities. Simplified formulas for the residual drift ratio \theta _\textR and the equivalent viscous damping \xi _\texteq with the variation of the factor \lambda _\textED are proposed through regression analysis and verified by existing cyclic lateral loading test data. The study results show that the proposed formulas provide a design method for optimizing the self-centering and energy dissipation capacities and can be used to guide the design of posttensioned precast segmental CFDST piers.

     

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