重载铁路桥梁体外预应力筋加固性能研究OA北大核心CSTPCD

The operational load lifting leads to the problems of strength degradation and stiffness deterioration of bridges for heavy-haul railway,making it crucial to strengthen these structures.In order to investigate the reinforcement performance of heavy-haul railway bridges with external prestressing tendons(EPTs),both fatigue and post-fatigue monotonic tests were conducted on unreinforced and reinforced full-scale 24 m ultra-low height prestressed concrete(PC)beam test models.Finite element(FE)models of unreinforced and reinforced PC beam were established.Through tests and FE analysis,the monotonic and fatigue properties of PC beams for heavy-haul railway before and after reinforcement were studied,and the laws of deflection and stress changes before and after reinforcement were revealed.The mechanical properties of PC beams under the action of different axle weight trains were revealed.The results show that the reinforcement effect is significant.In fatigue tests,the reinforced beams exhibite significantly lower stiffness degradation,mid-span deflection,stress of internal prestressing tendons,and stress in the bottom and lower flange of the concrete compared to the unreinforced beams.In the operation of 33 t axle weight and 1.2 times medium load(ZH)axle weight,the adaptability of 24 m ultra-low-height full-scale PC beams reinforced with external prestressing tendons is excellent,and the deflections and stress responses of 24 m ultra-low-height full-scale PC beam of the reinforced heavy-haul railway meets the specification requirements.The findings can provide useful references for the design,maintenance and strengthening of bridges for heavy-haul railway.