The Local Mechanical Characteristics Analysis And Model Test Research Of Railway Steel Truss Girder Cable-Stayed Bridge With K-Shaped

Bei Jiang large span bridge, a steel truss girder cable-stayed bridge of the newly built railway from Guiyang to Guangzhou, firstly used a vertical and horizontal girder bridge system with K-shaped. This kind of deck system is a brand new improvement to the traditional one. Concrete deck is adopted for the end of side spans and the two spans next to them and orthotropic steel deck is used for the rest part of the deck. Through finite element simulation, mechanical properties of the cable-stayed bridge for high-speed railway were analyzed in depth. Influence of different kinds of K-shaped on the performance of the deck was analyzed which could be used as reference for the similar deck design of other bridges. Based on the simulation, local segmental model of the K-shaped for static load test was established after optimizing the model structure and supporting structure. Then the actual force status of the cable-stayed steel truss railway bridge deck system with the K-shaped is obtained. The main research contents and outcomes are as follows.1. Structure analysis, including the whole bridge beam model analysis and beam system combining multi-scale shell element analysis. The former calculation use the finite element software MIDAS, the most unfavorable internal forces of the K-shaped in full-bridge is determined. The latter used ANSYS finite element software to establish space segmental shell element model, which focused on the analysis of local stress distribution. Through simulation analysis, the mechanism of force and the stress level of the K-shaped, the longitudinal beam, beam bar under dead load and live load are analyzed. The calculation results show that the stress level of each bar are low, K brace structure can effectively reduce the horizontal stress of longitudinal beam, horizontal beam, and the cross rib caused by out-of-plane bending. Therefore, overstressing of the horizontal beams the traditional vertical and horizontal girder bridge system which caused by out-of-plane bending can be solved effectively.2. According to the shell element model, preliminary discussion of effect of different K-shaped structure form on the mechanical behavior of bridge deck system was presented. By analyzing the mechanical characteristics of longitude beams, horizontal beams, transverse ribs, the integral joints of bottom chord bar as well as K-shaped in different models such as model without K-shaped, with K-shaped of T-shaped section or I-shaped section, it is found that the bridge deck system of T-shaped section K-shaped can effectively reduce the local stress of bars, and the stress of deck is more reasonable.3. Based on the simulation analysis and focuses on the K-shaped, local segmental model of the K-shaped is established. The results showed that the theoretical stress was in good agreement with the experimental stress, and the fine finite element analysis can be adopted to determine local stress distribution of bridge structure effectively. In the loading process, each of test points remains in a linear elastic state. Moreover, its stress meets the needs of design and the structure have sufficient reserved capacity for safety.