Sensitivity Analysis On Construction Error Of Long-span Steel Trussed Arch Bridge

Steel truss arch bridge has the advantages of beautiful appearance,large ability to cross,high carrying capacity,and thus in the railway bridge and large span bridge design has become a very competitive bridge type.In order to improve the construction quality of the long-span steel truss arch bridge and ensure the structural safety during the construction process,this paper uses the finite element program MIDAS Civil to establish the finite element method with the span of 70 m + 240 m + 70 m based on Su-ling mountain main bridge.The effects of structural self-weight,stiffness,temperature and assembling angle error on the arch rib and stress of the critical construction state of the bridge are studied.The main work of this paper is as follows:(1)The ideal state calculation model of large span steel truss arch bridge is established,and the change of construction process and boundary condition is simulated.The realization method of structural self-weight,stiffness,temperature and assembly angle error in the calculation model is discussed,so the influence of construction error Structural analysis model is established.(2)Comparing the cumulative deflection of the critical section of the arch ribs calculated by the error analysis model with the ideal model of the design,the maximum cantilever state,the arch girder and the different types of the arch ribs of the long span steel truss arch are studied The influence degree of construction error on the arch ribs and the position of the sensitive section of the arch ribs.The results show that the cumulative deflection of the different critical sections of the arch ribs in these three states is different from that of the same construction error.Under different construction conditions,the position of the cross section with the most sensitive to the construction error is different,The most sensitive cross-sectional position in the bridge state is mainly at 3/8L,while the most sensitive cross-section in the closed state is mainly at 1/2L.The arch ribs are the most sensitive to the assembly angle,the temperature is sensitive,the sensitivity of the structural stiffness is low.(3)The relationship between the critical cross-section stress and the ideal state model of the arch ribs calculated by the error analysis model is compared.The maximum cantilever state,the arch girder and the different types of the arch ribs of the long-span steel truss arch are studied.The influence of the error on the stress of the arch rib and the stress-sensitive cross-section of the arch rib.The results show that the stress changes of the arch ribs in the three conditions are different for the same type of construction error.Under different conditions,the stress and the lower chord stress on the arch ribs are the most sensitive to the main section,State and arch ribs in the state of the most sensitive cross-section of the main position in the 1/8L,and into the bridge state of the most sensitive cross-section position in the arch and 1/2L,the three state of the rib stress on the structure And the effect of the assembling angle on the maximum cantilever state of the arch rib and the arch rib stress of the arch ribs is small,and the stress on the arch ribs in the bridge state is relatively large.The structural temperature which has a great influence on the stress of the arch ribs with the largest cantilever state and the arch ribs,and the influence on the arch ribs in the bridge state is small.