The Research On Closure Scheme Comparison And Construction Monitoring Of High Pier And Long Span Prestressed Concrete Continuous Beam Bridge

The continuous beam bridge has the advantages of large structural rigidity,good force,small deformation,less expansion joints,smooth and smooth driving.With the construction of the cantilever casting method,the safety tension method,and the emergence and invention of the prestressed anchorage,the prestressed concrete continuous beam bridge has achieved great development and has become a very successful bridge type in the world.In China,prestressed concrete continuous girder bridges have been built in large numbers.With the development of bridges to the central and western regions,high-rise and long-span prestressed concrete continuous girder bridges that can span special mountains such as mountains,rivers,deep trenches and canyons are becoming more and more More is built.The internal forces,stresses and displacements of the main beam of a normal continuous girder bridge will change with the elongation of the cantilever section of the bridge and the transformation of the system.Due to the particularity of high piers and large spans,high-rise long-span prestressed concrete continuous girder bridges will be more complex than ordinary continuous girder bridges due to the variation of internal forces,stresses and displacements.In the actual construction of high-rise and long-span prestressed concrete continuous girder bridges,there will be situations in which the bridge is changed and closed due to various unknown factors.Different closing schemes will have different stress conditions and displacement situations.Therefore,it is of great practical significance to analyze the common collapse schemes of high-rise and long-span prestressed concrete continuous girder bridges.Linear monitoring is an important part of the bridge construction monitoring process.The quality of the linear monitoring directly affects the quality of the bridge after the bridge.The high-rise and long-span prestressed concrete continuous girder bridge is different from the ordinary continuous girder bridge.This type of bridge is difficult to construct,and the requirements for bridge line monitoring are higher.Find a suitable line shape of high-rise and long-span prestressed concrete continuous girder bridge.Monitoring methods and relying on actual engineering to verify have very important practical significance.The main research work of this paper is as follows:(1)Briefly describe the factors that should be considered in the selection of the closed plan,and introduce the four kinds of close-up schemes commonly used in the high-rise and long-span prestressed concrete continuous girder bridges,and theoretically analyze the advantages and disadvantages of each of the four closed plans.One(edge spanning bracket?side span closing?system conversion?middle span closing)is the theoretical optimal closing scheme,and scheme 4(edge spanning bracket?midspan closing?side span closing?system conversion)is the theoretical suboptimal Close the plan.(2)Based on the iron furnace castle bridge,four kinds of closure scheme simulation models are established by using the finite element software Midas/Civil.Through numerical simulation,the internal force,stress and displacement of the four closure schemes are compared and analyzed.After the comparative analysis of the internal force,it is concluded that the dead load and prestress should be controlled in the internal force control.After comparing and analyzing the stress,it is concluded that different closure schemes have no obvious effect on the upper flange stress of the main beam,and different closure schemes have some influence on the stress of the lower flange of the main beam.When continuous beam bridge is linear control,the control time is long,the control node is many,the control difficulty is great,and the technical requirement is high,so the closure scheme which is easy to control linear control is regarded as the optimal closure scheme in numerical simulation analysis.In order to eliminate the blindness of the pre-arch comparison,the displacement control parameters of the closure scheme are introduced(the larger the linear control of the closure scheme is,the easier it is to control the alignment ofthe closure scheme).side span:E1=4.16,E2=0.13,E3.=1.69,E4.=1.7;Mid span:E1 =1.42,E2 =0.17,E3 =0.36,E4.=0.6.There is no significant difference between E3 and E4.in side span,and the construction of adding counterweight to the closing scheme 3 is more tedious,so it is considered that the linear monitoring of the closing scheme is the easiest,followed by the closing scheme 4,that is,the optimal closure scheme of the iron furnace castle bridge.The fourth scheme is the suboptimal closure scheme of Tielubao Bridge.(3)The Kalman filter method,grey system theory method,artificial neural network method and least square method are briefly introduced.The advantages and disadvantages of these four linear monitoring methods are compared and analyzed from the aspects of definition,prediction accuracy and the conditions needed to establish the model.It is concluded that the grey system theory method is a more suitable linear monitoring method for long-span prestressed concrete continuous girder bridges with high piers.(4)The theory of grey system theory and its three GM(1.1)models are introduced in detail.Based on the linear monitoring project of Tielupao Bridge,the metabolic GM(1.1)model,full-data GM(1.1)model and partial-data GM(1.1)model are established.The fitting values and error rates of the three GM(1.1)models are compared and analyzed.The fitting values of metabolic GM(1.1)model are closer to the measured values,with an average error rate of 8.71%,which is the smallest of the three models.It is verified that the grey system theory method is more suitable for linear monitoring of long-span prestressed concrete continuous beam bridge with high piers.The GM(1.1)model of metabolism of grey theory is the recommended model of the three models.