Research On External Prestress Reinforcement Technology Of Railway Steel Truss Bridge

With the continuous development of modern society,the traffic volume has increased sharply,the load of heavy vehicles has increased,and the in-service steel truss bridges have suffered from excessive deformation and insufficient bearing capacity.Some bridges are no longer suitable for continued bearing and need to be reinforced.The construction of external prestressed reinforcement technology is flexible,economical,and has little damage to the original structure.At present,external prestressed reinforcement technology is mostly used in long-span roof truss steel truss beams and concrete beam bridges.The reinforcement effect is good,but there are few studies on the reinforcement of railway steel truss bridges.This paper systematically studies the method of externally prestressed reinforcement of railway steel truss bridges.The main research work and conclusions are as follows:(1)Introduce the concepts of fuzzy mathematics and analytic hierarchy process,and summarize the calculation steps of analytic hierarchy process.In view of the damage of steel truss bridges,three kinds of reinforcement schemes are proposed,and the fuzzy comprehensive evaluation method is applied to the comparison and selection of reinforcement schemes.Through calculation and analysis,external prestressed reinforcement is first considered when strengthening railway steel truss beams.(2)Comparing the effects of straight-line and broken-line reinforcement on simply-supported steel truss beams through modeling and calculation by ANSYS finite element software;the calculation formula of the prestress increment of external reinforcement of simply-supported and continuous steel truss bridges is derived.The reinforcement design requirements for externally prestressed beam reinforced steel truss bridges are summarized,such as the type of prestressed tendons,external beam anchoring,steering,and vibration reduction systems.(3)The external prestressed reinforcement of simply-supported steel truss bridge and continuous steel truss bridge were studied respectively.The ANSYS finite element is used to model the two bridges as a whole,and the bridges before and after the reinforcement are checked according to the specifications.(4)The schemes and precautions for externally prestressed reinforcement design of simply supported steel truss beams and continuous steel truss beams are given respectively.The simple-supported beam adopts double-direction broken-line reinforcement,and the size of prestress needs to be controlled;the continuous beam adopts multi-turned broken-line reinforcement,the outer reinforcement covers more stress,the diagonal web bar is closer to the bending moment diagram of the continuous beam,and the turning point The reinforcement effect is better when it is arranged near L / 5.(5)The force method was used to calculate the prestress increment of the external reinforcement of the simply supported beam bridge and the continuous beam bridge,respectively,and the variation rule of the prestress increment under the action of live load was studied.The live load increases.The prestress increment of the external reinforcement of the simply supported beam bridge is linearly related to the live load,and the prestress increment of the external reinforcement of the continuous beam bridge is linearly related to the live load.