板桁组合结构体系受力特性及计算方法研究

Study on Features of Force Bearing of Plate and Truss Composite Structure System and the Calculation Method

对板桁结构的各结构体系受力分析的目的是为了在设计过程中能根据各体系的受力特点 ,对不同的构件进行有针对性的设计。文中针对芜湖长江大桥连续梁的板桁组合结构各体系受力的情况 ,在板桁组合结构计算分析中 ,将结构划分为 3个体系 ,对各体系的受力情况进行了具体分析计算。认为板桁组合结构第一体系受力的最主要的特点 ,是混凝土桥面作为主桁上弦杆翼缘的一部分参与结构整体受力 ,在恰当考虑桥面有效宽度后 ,第一体系的受力分析可以按常规的杆系结构分析办法处理。第二系为由纵横梁及桥面板构成的加劲板 ,可采用叠加桥面板单元的网格梁组合模型进行分析。而第三体系受力主要是分析其在轮压荷载下的受力状态 ,分析时应按实际情况考虑多个车轴下的轮压布置 ,并考虑纵梁支承刚度差异带来的影响。

The purpose of analyzing the force bearing of various structure systems of the plate and truss structures is to design specifically for different structures according to the features of force bearing. The paper breaks the structures into three systems in the calculation and analysis of the plate and truss composite structures in consideration of the force bearing conditions of the continuous beam′s plate and truss composite structure of the Yangtze River bridge. Then specific analysis and calculation is carried out according to the forcing bearing situation of each system. The paper holds that the first system of the plate truss composite structure features that the concrete bridge deck is subject to the force of the integral structure as a part of the side end of the top chord tier of the main truss. After properly considering the effective width of the deck, the force bearing of the first system can be analyzed by conventional bracing system structure method. The second system is the strengthening plate consisting of the longitudinal and transversal beams and the bridge deck plates. It can be analyzed with grid beam composite model of the overlapped bridge deck plate unit. The force bearing of the third system is analyzed when the bridge is under load. During the analysis, the distribution of loads of several wheelsets, as the real situation is, shall be considered and the influence of the different longitudinal and transversal beams′ supporting rigidity shall also be considered.