高性能钢管混凝土组合桁梁桥

提出一种新型桥梁结构形式——高性能钢管混凝土组合桁梁桥。从结构性能方面阐述该组合桁梁桥高效传力机制、高性能结构构件及节点力学性能，从预制件划分、存放、运输、拼接方面阐述组合桁梁桥高效装配施工性能，从防灾性能方面对组合桁梁桥与混凝土梁桥进行抗震性能有限元对比分析，从耐久性能、可维护性能及环保性能方面论述组合桁梁桥良好的服役性能。结果表明：高性能钢管混凝土组合桁梁桥各杆件受力明确，杆件材料利用率高，结构刚度大，当结构跨径达到80 m时，用钢量指标仍在400 kg·m^-2以下；PBL加劲型等宽钢管混凝土节点可有效改善节点传力性能、静力破坏模式及抗疲劳性能；PBL加劲型矩形钢管混凝土构件可改善钢混界面传力及钢管局部屈曲性能，有效提高构件承载力；组合桁梁桥主桁单元、桥面板单元、桥墩单元可在工厂标准化生产，预制构件单元质量可控，现场装配速度快，施工周期短；与混凝土箱梁桥相比，组合桁梁桥结构体系地震响应内力下降显著，反应谱分析中纵桥向墩底弯矩与剪力下降达94.0%、81.2%，时程分析中纵桥向墩底弯矩下降达91.6%；采用可更换桥面板构件、桥墩系梁构件使组合桁梁桥全寿命周期性能优异。可见，矩形钢管混凝土组合桁梁桥是一种装配式高性能桥梁结构体系，可为中国中等跨径公路装配化桥梁设计提供参考。

High-performance CFST Composite Truss Bridge

A new type of bridge-high-performance concrete-filled steel tubular (CFST) composite truss bridge was proposed. The structural performance of the composite truss bridge that considers a highly efficient force-transfer mechanism, high-performance structural component, and joint mechanical properties was introduced. Prefabrication of the composite truss bridge was presented, which included the prefabricated-member classification, deposition, transportation, and connection. The anti-disaster performance of the composite truss bridge was expounded by comparatively analyzing the seismic performance of a prestressed concrete box-girder bridge using the finite-element method. The service performance of the composite truss bridge in terms of durability, maintainability, and environmental protection point was considered. The research results shows that the high performance CFST composite truss bridge contained truss members with adequate force-bearing state, high material utilization, and large stiffness. The steel-quality index remained under 400 kg·m^-2 when the span reached 80 m. The CFST aequilate joint stiffened using PBL can effectively improve the joint force-transfer mode, failure mode, and anti-fatigue performance. The CFST component stiffened with PBL can improve the steel-concrete interface force transfer and local buckle performance of the steel tube, which greatly enhances the component capacity. The main-truss, concrete-slab, and pier elements of the composite truss bridge can be manufactured under a standard production process in the factory. Meanwhile the quality of the prefabricated components can be controlled, and quick assembly speed and short construction period characterize the prefabrication process. Compared with a prestressed concrete box-girder bridge, the internal-force seismic response of a composite truss bridge significantly decreases, the longitudinal moment and shear force in the response-spectrum analysis at the bottom of the pier decrease by 94.0% and 81.2%, respectively, and the longitudinal moment in the time-history analysis at the bottom of the pier decreases by 91.6%. The use of a replaceable concrete slab and pier tie beam enables the composite truss bridge to possess excellent total life-cycle performance. Therefore, the composite truss bridge is a type of prefabricated high-performance bridge that can provide a good reference for the design of highway prefabricated medium span bridges.