Analysis Of Loading And Strengthening Of Long-span Steel Truss Girder Bridge

With the rapid development of the world economy,the traffic volume and load levels of various regions have been increasing.Due to the low load level of the original design,some large-span steel truss girder bridges have experienced excessive deflection and stress under the existing load.The bearing capacity cannot meet the current use requirements.In this paper,the loading and strengthening of large-span steel truss bridges are studied.The external prestress method with higher loading capacity,the addition of stay cable method and the addition of suspension cable method are selected for reinforcement.The finite element modeling is us ed to analyze the reinforcement,The improvement of the mechanical performance of the bridge provides a theoretical reference f or the reinforcement of the same type of bridge.The main work of this article is as follows:(1)Through the analysis of the external prestressed reinforcement theory,it is proposed to use three types of external prestressed steel beams to strengthen the steel truss bridge.The full bridge model was established by finite element software,the changes in the internal force values of all members after reinforcement were analyzed,the changes in the number of steel strands were studied,and the load capacity of the steel truss girder bridge was improved.The results show that one bundle of 11 steel strands is the most suitable reinforcement plan by external prestressing method.(2)When additional cable stays are added for reinforcement,the internal force values of each member are analyzed through finite element modeling to study the effect of tower height,cable stay anchor point,cable stay tension,and the density of cable stay arrangement on reinforcement.The results show that the long-span steel truss girder bridge should adopt the conventional tower height,densely arranged cable stays,and arrangement anchored on the lower chord,which is the most suitable reinforcement plan.(3)According to the suitable range of the vector-span ratio of the newly-built ground-anchored suspension bridge in the code and the mechanical characteristics of the suspension bridge,it is proposed that the tower height of the tower should be 16.6m unchanged,and the three vector spans of 1/9,1/10 and 1/11 should be selected reinforced by suspension cable method.Finite element modeling was used to verify the reasonable completion of the steel truss beam after suspension cable reinforcement.The stress values and stress distribution trends of the bridge members before and after the reinforcement with three different span ratios were compared.The steel truss girder bridge with a span of 1/9 should be reinforced with a vector span ratio.(4)By comprehensively comparing the three reinforcement methods,it can be concluded that the external pr estressing method does not have high requirements on the surrounding environment of the bridge,and it is the preferred reinforcement scheme for the OMO Bridge when meeting the requirements for load reinforcement.After adding the cable stay method and the suspension cable method,the bearing capacity of the whole bridge is increased more than the external prestress.However,these two types of reinforcement methods have very high requirements on the geology of the bearing platform and anchoring end,and ar e more suitable for the load requirements.Reinforcement of high steel truss bridges will be implemented as a long-term reinforcement plan for the O MO River Bridge.