Passenger Dedicated Line Deck Clouds Beam System Simply Supported Steel Truss Girder Bridges Research,

Through steel truss composite bridges have many advantages such as excellent rigidity, good integrity, low building height, slight noises and favorable dynamic performance. It will be applied widely in high-speed railway. Through steel truss composite bridges with Multi-crossbeam floor system offered in recent years can enhance the rigidity of the structure and improve the mechanical behavior of the bridge deck system. This paper studies mechanical behavior about Multi-crossbeam semi-composite and completely-composite floor system of the 64,80,106m three different span double-line simply-supported through steel truss composite bridges. The main work of this paper is as follows:1. The slab-truss composite structure space model was established by using finite method. The mechanical behavior and dynamic characteristics of three different span bridges with semi-composite and completely-composite floor system under dead load,live load and combined load was studied. The results show that the strength and rigidity of the three bridges all meet the requirements.2. The mechanical behavior and dynamic characteristics of through steel truss composite bridges with two type floor systems was compared and the respective mechanical characteristics was summed up. The results show that lateral stiffness of the completely-composite floor system is obviously larger than that of semi-composite floor system, the in-plane and out-of-plane bending moment of cross beams of semi-composite floor system is smaller than that of completely-composite floor system, especially for the end section of cross beams.3. The mechanical behavior under temperature of through steel truss composite bridges with Multi-crossbeam floor system was studied. The results show that the stress of end section of internode cross beam at end panel of semi-composite floor system is about 90.0MPa and the tension stress at the top of the mid-section of concrete slab is about 2.5MPa when the temperature of main truss is 15℃higher than the concrete slab and the cross beams.4. The mechanical characteristics about the frist system of bridge deck system was studied. The results show that the degree of coaction by bridge deck system and main truss of completely-composite floor system is higher than that of semi-composite floor system, for example: under the 2nd-stage dead load, the percentage of longitudinal axial force was shared by bridge deck system of 80m span bridge with semi-composite floor system is 25～30% and the percentage of longitudinal axial force was shared by bridge deck system of completely-composite floor system is 32～40%.5. The mechanical characteristics about the second system of bridge deck system was studied. The results show that the ratio of internode cross beams to node cross beams about vertical bending moment of inertia under 0.4 is suitable.6. The mechanical behavior of three different span bridges with same kind composite floor system was compared. The results show that the axial forces in main truss members of three span bridges is the same increasing with the increased span, so their sections is increasing from samll span to large span. Maximum value of out-of-plane bending moment of end section of the cross beams is also increasing with the increased span. the degree of coaction by bridge deck system and main truss of three different span bridges is almost the same.The research results of this paper will be referenced to design for Passenger Dedicated Line simply-supported through steel truss composite bridges with multi-crossbeam floor system.