节段预制变截面波形钢腹板PC组合箱梁桥弯剪受力性能研究

The segment prefabrication assembly technology has the characteristics of rapid construction, effective quality control, good environmental protection and low cost which meets the requirements of industrial development of high quality, high efficiency, green construction, energy saving and environmental protection. It is necessary to reduce the structural weight and reduce the influence of joints when this technology is applied to the long-span bridges. The composite box girder with corrugated steel webs is used to replace the traditional concrete girder, which can achieve the purpose of light weight, convenient transportation and hoisting. It also has the advantages of clear transmission force and significant economic effects which has a good application prospect in the construction of long-span bridges. Combining the technical characteristics of segment prefabrication and hybrid tendons, and considering the influence of variable cross-section effect and accordion effect, the bending and shearing behavior of the large-span precast segmental non-prismatic PC composite girder bridges with corrugated steel webs are quite different from prismatic segmental members and the monolithic members. Thus, this project is mostly concentrated on theory and experimental research of the bending behavior, the shearing behavior and the failure mechanism under shear-moment loading of the large-span precast segmental non-prismatic PC composite girder bridges with corrugated steel webs. Then put forward the corresponding design calculation method, improve its design theory, and provide theoretical basis for the promotion of this type of bridge type.

节段预制拼装技术具有架设速度快、质量容易控制，环保性好、成本低等特点，符合国家“优质高效、绿色施工、节能环保”工业化发展要求。将该技术应用在大跨径桥梁中，需减轻结构自重，降低接缝影响，采用波形钢腹板组合箱梁代替传统混凝土箱梁，可达到节段轻量化，便于运输和吊装等目的，且具有传力明确，经济效应显著等优势，在大跨径桥梁的建设中具有较好的应用前景。结合 “节段预制”、“体内-体外混合配束”等技术特点，并考虑大跨径波形钢腹板PC组合箱梁的“变截面效应”和“手风琴效应”的影响，其弯剪性能与节段预制等截面梁差异显著，亦不同于整体现浇梁。鉴于此，本项目主要针对这些结构特点，围绕大跨径节段预制变截面波形钢腹板PC组合箱梁桥受弯特性、受剪特性及弯剪复合作用下失效机制等关键问题开展理论与试验研究，并提出相应的设计计算方法，完善其设计理论，为该类桥型的推广提供理论依据。

节段预制变截面波形钢腹板组合箱梁桥属于一种新型的桥梁结构，可实现结构全预制加工及轻量化快速施工，符合我国公路桥梁向工业化和标准化建设的发展趋势。本项目采用模型试验、理论分析、数值模拟相结合的方法系统研究节段预制变截面波形钢腹板组合梁桥弯剪承载性能及传力机理。首先，考虑施工工艺和配束比影响，开展了节段预制波形钢腹板PC组合梁抗弯性能研究，揭示节段预制波形钢腹板PC组合箱梁抗弯机理，并提出节段预制波形钢腹板PC组合箱梁抗弯承载力计算方法；其次，以南京长江五桥为背景，开展了节段预制变截面波形钢腹板PC组合梁抗剪模型试验，探明了变截面波形钢腹板组合梁接缝处组合截面剪应力沿高度方向的分布规律及接缝截面承剪机制，综合考虑Resal剪切效应、预应力弯曲效应产生的附加剪力及接缝削弱效应，提出了考虑剪力修正的节段预制变截面波形钢腹板PC组合梁剪应力计算公式；基于模型试验探明了弯剪复合作用下节段预制波形钢腹板组合梁承载机理，基于此提出弯剪复合作用下的失效机制划分方法；最后，通过参数敏感性分析明确了节段预制波形钢腹板组合梁桥不同跨径下节段划分长度、体内-体外混合配束比例等关键设计参数，并结合数值模拟明确波形钢腹板节段梁堆放及吊装要求，提出相应控制指标。相关研究成果可完善节段预制变截面波形钢腹板PC组合梁桥设计理论，为该类桥型的推广应用奠定理论基础。