Research On Spatial Stress And Track-bridge Interaction Of The Long Span Railway Simply-supported Steel Truss Girder

The simply-supported steel truss girder is widely used in railway bridge, because of definite stress, lower structural height, light weight and short construction period. Track-bridge interaction emerged with the extensive use of continuously welded rails(CWR) on the railway bridge. Up to now, the existing research on track-bridge interaction has been mainly focused on concrete simply-supported bridges, continuous bridges and cable-stayed bridges, while relatively less work on the steel truss bridges. In this paper, based on156m simply-supported steel truss girder of Huangling Hancheng Houma railway, some research had been done in the mechanical characteristics and track-bridge interaction of the steel truss bridge. Main content of this paper is presented as follows:1、The plane model, space model of open deck and RPC deck are established according to the design information. The spatial stress of the main trusses and bracing in the three models were analyzed and compared, and the influences of spatial stress in vertical and horizontal beams were analyzed when the stringer set two disconnections.2、The ideal elastic-plasticity resistance model was selected to simulate the longitudinal resistance between the rail and girder. An integrative pier-beam-rail was established on the basis of open deck space model. In this paper, the distribution of additional expansion and contraction force, flexural force and braking force were analyzed separately and the strength of rails was checked, considering the unfavorable combination of longitudinal forces. The rail stress, the distribution of displacement and the width of breaking joint were analyzed under a special load case of rail broken case. In addition, the influences of the different brake pier stiffness for additional expansion and contraction force, flexural force and braking force were analyzed.3、The additional longitudinal forces, caused by the track-bridge interaction when the small resistance fastener was applied, were calculated and studied. The results indicate that the additional compressive stress of expansion and contraction and a combination of additional stress in rails can be reduced greatly when small resistance fastener is used. It’s beneficial to the strength of the rail. The study of CWR for the simply-supported steel truss girder bridge shows that the compressive stress of rail at movable end of the steel truss bridge still can’t meet the strength requirements when the small resistance fastener is applied. So in the laying of CWR, rail expansion regulator should be set in the movable end of the steel truss bridge.