Analysis Of Mechanical Properties For Joints Of Steel Truss Bridge

Steel bridges are widely used in construction because of their short period of building,light weight and strong ability of spanning.Each member of the steel truss bridge mainly bears the axial force.Compared with the steel plate girder bridges and steel box girder bridges,the steel consumption does not increase significantly with the increase of the span.Therefore,its economic competitiveness is more prominent in long-span bridges.This article is based on the engineering background of the newly constructed superstructure of a bridge.The newly constructed superstructure bridge is a through-type three-span continuous steel truss bridge with a span of 60 + 100 + 60 m.In this paper,Midas Civil is used to establish a space finite element model of the three-span continuous steel truss bridge.Based on the internal force results of the full bridge model,a local node model is established.And then analyze the force changes of local models when different parameters are changed.In the actual construction and operation process,various diseases will occur in high-strength bolts.Establish a local model of the node connection.Simulate the effect of different pretensions of high-strength bolts,and explore the effect on the actual force at the node connection The main research work of this article are as follows:(1)Use Midas Civil to build a full bridge model,simplify the simulation method of connection method,construction process and bridge load according to the actual stress of the bridge.Extract the internal force of the rod from the overall model.And select the node with the unfavorable force according to the internal force result of the lower chord.(2)Use ANSYS to build a local model of the node.Extract force and displacement boundary conditions from the global model and apply them to the local model.Change the parameters such as the thickness of the lower chord,thickness of top and bottom plates of box section and the length of the web rod extending into the gusset plate.By establishing 4 nodal path lines,the changes of the nodal stress on each path line are analyzed when the node model changes with different parameters.(3)Steel truss bridge members are mainly affected by axial forces.Establish a local finite element model of the abdominal rod.Analyze the force situation at the connection of the abdominal rod and the force transmission characteristics of each row of bolts under the action of the axial force.(4)By changing the tightening state of the bolts at different positions of the abdominal rod,the changes in the friction of the contact surface,the changes in the stress of the connecting plate and the changes in the force transmission effect of each row of bolts are analyzed under different preload conditions.(5)Simulate the damage of screw during operation through finite element software.Analyze the force of the abdominal plate around the bolt hole.Then simply simulate the repair and installation of bolts and rods,and analyze the force changes in the original position.