Structure Analysis And Optimization Of Highway Bridge Erecting Machine

The Belt and Road(B&R)policy which was proposed by China in 2015 had an important significance in promoting the development of the regional cooperation better,stimulating the economic recovery and development,improving the influence of China in the world.The Ministry of Transport(MOT)issued a triennial action plan for transportation infrastructure construction involving 4.7 trillion RMB and over 300 traffic projects from2016 to 2018.These policies which aim at the infrastructure construction to improve the traffic conditions,promote urbanization and facilitate the flow of goods are significant meaningful.Owing to the limitation of terrain and construction environment in the Chinese highway construction,it needs overpasses and viaducts to solve the road interleaving and connect the highway.In the process of bridge construction,precast beams can be mass-produced,which is convenient for quality control.The bridge erector will erect precast beams on the piers.The lifting weight of bridge erecting machine is large and the effect of dynamic load is obvious.The structure of bridge erecting machine is greatly affected in the process of hanging beam and falling beam.Many safety accident are caused by structural buckling.Therefore,it is necessary to study the dynamic characteristics of the bridge machine.In addition,Two Sessions put forward to reduce steel production capacity.What lightens the weight of the structure helps to reduce material consumption,reduce costs and improve flexibility.Taking highway bridge erecting machine as the research object,select the typical working conditions from the bridge machine operation process to carry out strength analysis.On the premise of strength calculation,the structural stability and lateral anti overturning of the main beam are checked.Then the change of the key node displacements of the main beam and the change of the reaction force of the middle and rear legs are analyzed.Finally,optimize the structure of the main beam.The main contents of the full text are as follows:1.Introduce the main operation process and structure of bridge erecting machine.Select the transporting beam,erecting edge beam and cantilever moving longitudinally conditions,according to operating mode to combine the load of the bridge erecting machine to analyse the strength and stiffness of the structure.2.On the premise of the intensity calculation,carry out the linear buckling analysis of the bridge machine girder.Compare and select the condition of the minimum stability safety factor.The critical load of the linear analysis is loaded into the transporting beam position as the initial imperfection for the nonlinear analysis,and check the stability of the structure.Finally,analyse the lateral anti overturning of the bridge machine girder.3.Carry out the transient dynamic analysis of the change that the bridge machine girder is in craning beam and transporting beam.Obtain the change of the key points displacement on the main beam and the change of the reaction force on bridge erecting machine's legs,which provides references for the calculation of the legs' load.4.The bridge machine girder is made up of the same material.The optimization of the quality of the bridge machine girder is transformed into the optimization of the volume that is consumed.Take the maximum deflection and the allowable stress as the constraints.Take the cross section size of the bridge machine girder as the optimization variable to optimize the volume.Finally,analyze the optimization result to verify the rationality of the result.