Study On Quick-reinforcement Methods For Existing Simply-supported Railway Bridges By Simulation Of Vehicle-bridge Coupled System

Early in China, most of concrete bridges in the existing railway are divided T-beam bridges, and the bridges’ transverse stiffness is weak. The design maximum speed at that time is far below that of high speed trains, it’s only120km/h; and the design live load of the bridge can’t meet the requirements of heavy trains. At the same time as a result of prestressing loss and overload operation, the existing bridges’bearing capacity is not enough and transverse vibration is too excessive under the heavy trains and high speed trains. The existing reinforcement methods have a lot of shortcomings, such as need to interrupt the operation of railway, construction period is too long, and the effect of reinforcement is not obvious and not economical. So a quick-reinforcement method which can meet the safty and economical requirements should be proposed urgently.In this paper,32m-span prestressed concrete double T beam railway bridges are chosen as examples. And a new quick-reinforcement method that using external prestressed strands and precast concrete transverse diaphragms is proposed. Base on the analysis of natural vibration properties with ANSYS finite element software, the best reinforcement method is recommended.In order to prove the effectiveness of the selected reinforcement method, the dynamic response of bridge before and after reinforcement is calculated by the analysis of vehicle-bridge coupled system which simulated by the multi body dynamic software UM. Then the dynamic property of bridge before and after reinforcement under the heavy train and high speed train with different velocities is calculated. Finally the effects of different track irregularity and Rayleigh damping parameters to the calculation of bridge dynamic simulation are analyzed.The resonance mechanism and conditions of vehicle-bridge system are studied in this paper. The causation that changing the reinforced bridges’resonance response is pointed out, and the coupled vibration between vehicle and bridge under the two different high speed trains is analyzed. The validity of vehicle-bridge system’s resonance principle and the reliability of resonance response of the reinforcemented bridge are all confirmed.