Research On Structural Behavior Of Through Steel Tied Arch Brdige On High-speed Railway

With the quick development of high-speed railway, there is a great chance that the high-speed railways go across the city roads and highways, with the span range that needed is from90m to150m. When higher clearance under deck and lower deck elevation of the bridge is required, through steel tied arch bridge is used at home and abroad for its unique advantages such as low deepth under deck, large spanning ability, good appearance, low interfere during construction etc. But the application is not widely used and the study has not been in throughly. Based on the requirements of high-speed railway bridge, such as bridge stiffness, stress, deformation, dynamic behavior and fatigue property, and the summaries of the research achievements at home and abroad, in the engineering background of Fu-xia through steel tied arch bridge with a span of128m, a systematic study has been conducted on the structural behavior of through type steel tied arch bridge in high-speed railway.Firstly, the structure systems of through steel tied arch bridge is thoroughly studied and suitable structure forms for such bridges are proposed. The effect of hanger type, relative stiffness ratio of arch ribs and tie beam, arch rib inclination, transverse joints system of arch ribs, the ratio of span to rise and deck type on structure dynamic characteristics, stiffness, forces and deformation is studied systematically by finite element method. Under the consideration of integrated factors of force, construction and the amount of steel, the reasonable structure type, namely steel orthotropic deck with the ratio of span to rise1/5, parallel arch, rigid hanger, I-type transversal support, dense crossbeam with stringer, is proposed for through steel tied arch bridge in high-speed railway. The128m steel tied arch bridge in Fuzhou-Xiamen railway is taken as the case of study and the static performances of the bridge are calculated and analyzed in a variety of load combinations. It is found that structural stress, deformation and other indexes have met specification requirements, which has further verified the rationality of the proposed through type steel tied arch bridge for high-speed railway.Secondly, for some typical structure details of through type steel tied arch bridge in high-speed railway, including a serious of structure location such as six kinds of arch skewback, orthotropic deck, joint between hanger, arch rib and tie beam, joint between crossbeam and tie beam, the finite element method is taken to analyze the fatigue stress of the structure, and the key fatigue location in the various connection details have been studied. Reasonable structural type of the arch skewback is proposed according to the fatigue performance. As there is no special regulation for railway orthotropic bridge, loading method of fatigue load and fatigue resistance is explored and it is found that the main structure details with great fatigue stress amplitude exist in fillet weld seam location in the connection of closed rib and deck, the location between closed rib and crossbeam, the plate between closed rib and inferior crossbeam, the transverse matching belt of closed ribs, the transverse matching belt of stringer and crossbeam.Then, for the orthotropic steel bridge decks of through steel tied arch bridge in high-speed railway, in order to take a deep study on the applicable performance, law of stress distribution and load transfer path and inspect the reliability of the construction details, a1:2geometric scale is used and a section model test is carried out, focusing on the stress and deformation law of beams, decks and U rib under the single line load and double line load. The validity of calculation theory and the proposed method is proved by comparative analysis of experimental data and the proposed method.Finally, based on theoretical analysis, for the parts which have larger fatigue stress amplitude in orthotropic steel bridge decks of through steel tied arch bridge in high-speed railway, a1:1geometric scale fatigue test model is made, including the deck, three U ribs, two beams and two simulative tie beams. The fatigue tests verify that the fatigue reliability of the typical structure of the orthotropic steel deck under train live load and show that the proposed structure details of orthotropic steel bridge deck can meet the fatigue performance requirements of high-speed railway bridge.This paper systematically deals with the structure system, structure type, bridge deck and construction of key loctions of through steel tied arch bridge. Through the model test, the calculation method and results are analyzed and verified. Also, the variation law of stiffness, stability, force, dynamics performance and fatigue performance is summarized systematically, providing basis and reference for through type steel tied arch bridge in the application of high-speed railway bridges.