Study Of A Long-span Continuous Triple-main-truss Variable-height Steel Railway Bridge With Four Lines

Abstract:ZJXZH Bridge is a triple-main-truss variable-height continuous steel truss bridge with four lines crossing the Yellow River, using orthotropic steel bridge deck. This paper used spacial finite element analysis method for the whole bridge and fine finite element analysis method for the local section of the bridge deck, systematically analysed deformation and stress of the whole bridge, local stress of key parts of the bridge deck. The major work and results were as follows:1.The space finite element analysis method for ZJXZH bridge was studied. A special FEA model for the whole bridge of ZJXZH Bridge was established by using the spacial plate-beam method. The mechanical characteristics and force performances of the bridge under dead load、 worst-case load and combination of main loads were analysed. The main analysis results showed:the whole bridge had a reasonable bearing structure,the rigidity and strength satisfied requirements.2.According to the analysis of the whole bridge, four key parts of junction of longitudinal and beams (ribs) in deck dystem under weak stressing condition were selected. The local finite element analysis method of key parts were studied. Four fine FEA locality models were established by using the finite element analysis software-ANSYS.3. The mechanical behavior of each key part of deck system under a variety of operating conditions was analyzed. The results showed:the stress of most area was not larger, but the stress of the crossgirder-web’s hole edge where U-ribs went through E8joint crossgirder was comparatively larger. Mises equivalent stress reached402MPa, which was above allowable stress. The amplitude of principal tensile stress was not large, anti-fatigue properties of deck system being fine.4. Based on the original program, the effect of structure details on local stress was studied. Structure details mainly include beams web openings or not, the height of the stringer and the thickness of beam web. The results of comparative analysis showed:reducing the height of stringers properly or thickening beams web can effectively reduce the local stress of junction of longitudinal and beams (ribs). The results of this article provide design basis for ZJXZH Bridge, and are of reference value to other similar bridges.This paper has118graphs,28tables and62references.