| In recent years,prefabricated technology,with its construction speed is quick,safe,environmental protection and the advantages of little impact on the traffic environment has been more and more widely used in bridge construction.As a bridge to the upper structure,large-tonnage whole hole precast concrete box girder also conforms to The Times in development gradually.The development of Large-tonnage whole hole precast box girder erection technology has a positive effect on our country urbanization construction and bridge construction.When the viaduct is built on existing roads,the use of asymmetric large-tonnage prefabricated concrete box girder will become an inevitable trend in the development of bridge constructiondue to the limitation of existing road width requirements.At present,the study on stress state of box grider and the lower structure in the process of erection mainly for symmetrical large-tonnage prefabricated box girder,while the asymmetrical are relatively few.The upper part of the bridge structure of an expressway project is asymmetric large-tonnage concrete box girder,which is used for the first time in the conventional highway bridge of our country.In order to further understand the stress state of box girder and the lower structure in the process of asymmetrical large-tonnage prefabricated box girder erection,based on the engineering background,this paper uses the finite element numerical analysis and field test method to study the stress state of box grider and the lower structure.The main research content is as follows:(1)Introduce the construction technology of the asymmetric large-tonnage prefabricated box girder,and clear the loading conditions in the process of box girder scale erection.Use the Midas/Civil to establish the finite element modal of the asymmetric large-tonnage prefabricated box girder with beam element,and the corresponding analysis results are obtained by loading the box girder in each load condition.Studies have showen that the transport beam car walks in place is the most ufavorable load conditions;(2)Use ANSYS to calculate and analyze the element model of the box girder under the most unfavorable load conditions and the traversing in-situ condition to study the local force of the box girder and compare with the calculation results of the beam element modal.Studies have shown that the maximum value of longitudinal tensile stress appears in the bottom web of the middle and short flange in the most unfavorable working condition,and the maximum value of compressive stress appears in the top web of the middle and short flange.The maximum value of the transverse tensile stress of the box girder appears between the legs in the bridge;(3)Ansysis the stress state of box girder and the lower structure in the process of prefabricated box girder scale erection under different working conditions.The difference between the force of the box girder and the lower structure under each working conditions is compared and comparing with the theoretical results.Through the study,it is found that the transport beam car walks in place is the most unfavorable load condition for the box girder,and the box girder traverses in-situ is the most unfavorable load condition for the lower structure.The measured results are in good agreement with the theoretical results. |
