中等跨径装配式矩形钢管混凝土组合桁梁桥设计

优化了传统混凝土箱梁腹板与底板, 提出了装配式桥梁新型结构形式——矩形钢管混凝土组合桁梁桥, 从总体设计、主桁选型、横断面选型、桥面板选型、杆件选型、节点选型与连接构造方面介绍了其结构设计优化过程; 从桥梁的静力性能与地震响应、桥面板的有效宽度与负弯矩区力学性能方面对矩形钢管混凝土组合桁梁桥进行了有限元分析, 并将部分组合技术应用到负弯矩区桥面板连接件的设计中; 从技术性与经济性角度将矩形钢管混凝土组合桁梁桥与预应力混凝土箱梁桥进行了工程量和施工便捷性对比。研究结果表明: 矩形钢管混凝土组合桁梁桥结构选型符合桥梁预制装配、快速建造的工业化要求, 主桁各杆件受力明确, 受力形态主要为轴向拉、压力; 负弯矩区桥面板有效宽度系数为0.899;采用部分组合技术可使桥面板轴向拉力下降75.3%, 有效地提高了桥面板的抗裂性能; 矩形钢管混凝土组合桁梁桥初始输入地震力占同等跨度预应力混凝土箱梁桥的58.9%, 说明矩形钢管混凝土组合桁梁桥具有良好的抗震性能; 钢材用量、混凝土用量、上部结构质量与预应力混凝土箱梁桥的比值分别为1.241、0.485、0.575, 说明矩形钢管混凝土组合桁梁桥结构轻巧, 材料利用率高, 工程造价低, 具有经济优势。

Design of mid-span fabricated RCFST composite truss bridge

The webs and bottom slabs of traditional concrete box girder were optimized, and a new structural type of fabricated bridge named RCFST (rectangular concrete filled steel tubular) composite truss bridge was proposed. The structure design optimization procedure was introduced from the aspects of general design, main truss selection, cross section selection, bridge deck slab selection, member bar selection, joint selection and connection structure. The RCFST composite truss bridge was analyzed by finite element method from the static mechanical property and seismic response of the bridge, and the effective width and mechanical property of bridge deck slab in the negative moment zone of the slab. The partial composite technique wasalso used in the design of bridge deck slab connector in the negative moment zone. From the technicality and economy, the RCFST composite truss bridge was compared with the prestressed concrete box girder bridge in terms of engineering quantity and construction convenience. Analysis result shows that the selection of RCFST composite truss bridge structure meets the industrialization requirement of bridge's prefabrication and accelerated construction, and the member bars of main truss with clear force-bearing states mainly carry axial tensions and pressures. The effective width coefficient of bridge deck slab in the negative moment zone is 0.899. The axial tension of bridge deck slab decreases by 75.3% using the partial composite technique, which effectively improves the anti-crack ability of bridge deck slab. The initial input earthquake load of RCFST composite truss bridge accounts for 58.9% of the load of prestressed concrete box girder bridge with the same span, which indicates RCFST composite truss bridge has good anti-seismic property. The ratios of steel quantity, concrete quantity, and superstructure self-weight of RCFST composite truss bridge to prestressed concrete box girder bridge are 1.241, 0.485 and 0.575, respectively, which indicates the RCFST composite truss bridge has good economic advantages, such as simple structure, high utilization of materials and low building cost.