Research On Transverse Distribution Mechanism Of Truss Bridge With Vertical Loads

The internal force of main truss is not equal when a steel-truss bridge with two main trusses resist partial load. The internal force is overvalued when it is calculated by the lever principle method. With the development of economy and the increase of traffic flow, the bridge is wider, and the steel-truss bridge with three main trusses is designed and constructed. The steel-truss bridge with three main trusses is more complex and its spatial performance is more prominent. The internal force of main trusses are not equal when a steel-truss bridge with three main trusses resists self-weight. In this paper, mechanism of the internal force distribution of steel-truss bridge is studied based on its mechanical behavior. Specific work and conclusions are as follows:(1) The mechanical model of two composite beams with elastic constraints is presented and its analytical solution is obtained. Mechanism of the internal force distribution of steel-truss bridge with two main trusses when resisting partial load is studied. The internal force distribution of main truss is determined by the ratio of k横 and k纵 (km is defined as the vertical stiffness of the transverse connection system, and k纵 is defined as the ratio of main truss vertical stiffness and span to the fourth power in this paper). The internal force of main truss is more uniform with the ratio of k横 and k纵 increasing.(2) The mechanical model of three composite beams with elastic constraints is presented and its analytical solution is obtained. The internal force distribution of three main trusses are also determined by the ratio of km and k纵.The internal force of main truss is more uniform with the ratio of k横 and k纵 increasing.(3)The ratio of k横 and k纵 quickly increase when bridge become longer and the transverse connection system tends to be relatively rigid. The main truss internal force of long-span steel-truss bridge tends to be uniform and the transverse connection system is not very important to ensure the main truss sufferring force as a whole.(4) The mechanical model considering cable vertical stiffness of three composite beams with elastic constraints is presented to describe the behavior of three main trusses and three cable stayed bridge under self-weight. The influence of main structural parameters on the transverse distribution of internal forces is analyzed. The finite element model of hutong yangtze bridge is established and the influence of main structure parameters are discussed.