The Construction Control Of Continuous Beam Bridge And Analysis Of Spatial Stress Of Zero-block

With the rapid development of transportation industry in China,the continuous beam bridge with excellent structural performance and relatively low cost will play a more important role in our future road and railway construction.Cantilever casting method,a main construction method of continuous beam bridge in our country,the bridge constructed by it has to go through a long and complex process whose quality and alignment depend on a good construction control.At present,only one state prediction method is usually used in line shape control of continuous beam bridge in our country,and there is no attempt to combine the two state prediction methods.The calculation results of the beam element model are usually seen as the basis for stress control of continuous beam bridge,which fails to truly reflect the zero-block with complex stress state.Therefore,it is necessary to strengthen the research on the construction control of continuous beam bridge.In this paper,based on a continuous beam bridge of He'an High-speed Railway,the key problems in cantilever casting construction control of continuous beam bridge are studied.The Midas/Civil software is adopted to simulate the construction process of cantilever casting in continuous beam bridge,whose results are applied to the construction control of the continuous beam bridge.The gray GM(1,1)model,BP neural network model and parallel gray neural network model are established to predict and adjust the deformation value of poured concrete during continuous beam bridge cantilever construction,the effectiveness of results predicted by the three model is analyzed.The Midas/FEA software is used to establish the solid element model of the zero-block with the complicated stress state of the continuous beam bridge.The stress distribution status of the zero-block under five unfavorable conditions is obtained,and the calculation results of the solid element model of the zero-block and the calculation results of the beam element model are compared.The main findings of this paper are cited as follows:(1)The feasibility of grey GM(1,1)model,BP neural network model,and parallel gray neural network model in the continuous beam bridge linear control is verified.All three models can be used to predict and adjust the deformation value of poured concrete during continuous beam bridge cantilever construction.(2)Making comparisons between the prediction results of grey GM(1,1)model,BP neural network model,and parallel gray neural network model,the results indicate that the average relative error,the maximum relative error,and the root mean square error of the prediction results of the parallel gray neural network model are the smallest,which illustrates the superiority of the parallel grey neural network model in the application of linear control of continuous beam bridge.(3)The solid element model is established for the zero-block,and the stress distribution of the zero-block under the conditions of maximum cantilever state,bridge formation state,most unfavorable bending moment state,worst unfavorable axial force state,and most unfavorable shear force state is obtained.The results tell that the zero-block within all five conditions is under pressure and the stress state is reasonable.However,a large principal tensile stress,in the loading area of the diaphragm,the base plate entrance hole,and the top plate moving load,gives rise to the risk of partial cracking,which should be taken care of in these areas in the future design and construction control.(4)Compared with the calculation result of the zero-block beam element model,the calculation result of the zero-block solid element model is closer to the field stress monitoring results,which indicates that the zero-block solid element model can describe the actual stress state of the zero-block more accurately.In the stress control of the zero-block of a continuous beam bridge,the use of solid element modeling method will achieve better results.The research results of this paper provide a new idea for the application of state prediction method in the continuous beam bridge linear control.In addition,it has certain guiding significance for further design and construction control of continuous beam bridge in the future.