预制拼装桥墩抗剪性能及拼接缝剪切机理研究

With the application of precast bridge pier construction technology in high seismic risk areas and urban viaducts, cross-line bridges, an important technical problem is faced: how the shear performance of precast bridge pier under the earthquake or the collision of the vehicle is? Is segment-to-segment joint a vulnerable part? It has also become a technical problem for bridge design engineers and owners. In order to solve this technical problem, the main research contents are as follows: ①To carry out the shear test of different connecting detail joints, to study the shear behavior, damage of the joint interface at the seismic load or vehicle impact load, and the effect of various construction details on the shear mechanism of joint surface. ② The quasi-static tests of the small-shear-span precast bridge piers were carried out to study the shear behavior of the different connection details of precast bridge piers under the seismic loads. The hysteresis behavior, the ductile deformation, the damage mechanism, the failure mode of joint and the variation of the shear capacity of the joint at different damage levels were investigated. ③The numerical analysis model and the calculation method of the precast bridge pier which the joint shear behavior was described correctly were developed, and then, the sensitivity analysis of key mechanical parameters effect on the shear performance of the precast bridge pier was carried out. ④The calculation formula of shear strength of precast bridge pier was developed,and the improve the shear performance measures of precast bridge pier were proposed.

随着预制拼装桥墩施工技术在高地震危险性区域及城市高架桥、跨线桥中的应用，面临的一个重要技术问题就是预制拼装桥墩在地震、车辆撞击作用下的抗剪性能如何？拼接缝是否为易损部位？这也成为困扰桥梁设计工程师和业主的技术难题。为解决此技术难题，拟开展的主要研究内容如下：①开展不同连接构造拼接缝的直接剪切试验，研究拼接缝界面在地震荷载或车辆撞击荷载作用下的剪切行为、损伤和破坏模式及各种构造细节对拼接面剪切机理的影响；②开展小剪跨比预制拼装桥墩拟静力试验，研究在地震荷载作用下不同连接构造预制拼装桥墩的抗剪性能、拼接缝处的滞回特性、延性变形、损伤机理、破坏模式以及对应不同损伤程度下拼接缝界面抗剪能力的变化规律；③建立能正确描述预制拼装桥墩拼接缝剪切行为的数值分析模型和计算方法，在此基础上开展预制拼装桥墩抗剪性能关键力学参数的敏感性分析研究；④提出预制拼装桥墩抗剪强度计算公式和改善其抗剪性能的方法。

预制拼装桥墩施工技术在我国高地震危险性区域及城市高架桥、跨线桥中的逐步推广应用，面临的一个重要技术问题就是预制拼装桥墩在地震或车辆撞击作用下的抗剪性能如何？拼接缝是否为易损部位？这也成为困扰桥梁设计工程师和业主的技术难题。为解决此技术难题，开展的主要研究内容和重要成果有：①通过预制试件的直接剪切试验和数值分析研究，获得了灌浆套筒连接预制拼装桥墩不同构造拼接面在直接剪切下的剪切传力机理、损伤过程和破坏模式；②通过小剪跨比预制拼装立柱拟静力试验和数值分析研究，掌握了地震作用下，灌浆套筒连接不同构造预制拼装桥墩的抗剪性能（往复循环加载），包括拼接缝处的损伤行为、延性变形、破坏模式以及对应不同损伤程度下拼接缝界面抗剪能力的变化规律，并提出改善其抗剪性能的构造措施；③基于上述两类试验和理论研究以及撞击数值分析研究，建立了灌浆套筒连接预制拼装桥墩单向直剪抗剪强度公式与往复加载抗剪强度公式，同时考虑了剪跨比、延性、轴压力对抗剪强度的影响。能较好的估计脆性剪切破坏试件的抗剪强度。提出了水平极限承载力预测公式，能较为合理地预测剪跨比小于2.5的矮墩发生弯剪破坏时的水平极限承载力。④上述研究成果可供实际工程应用参考，并随着后续对该抗剪强度公式的进一步完善，可被相关规范采纳，具有较高的工程应用推广价值。