Research On Key Problems Of Construction Monitoring Of Prestressed Concrete Composite Box Girder Bridge With Corrugated Steel Webs

PC composite box girder bridge with corrugated steel webs is a new type of composite structure bridge,which uses corrugated steel webs instead of concrete webs on the basis of the original concrete box girder.It connects the steel webs with the top and bottom concrete by the shear connectors,making them work together.It has the advantages of light weight,assembly,reasonable stress and convenient construction.However,due to the difference of structure,its stress system and construction are different from the traditional concrete box girder bridge.So it’s necessary to study the construction monitoring of PC composite box girder with corrugated steel webs.In this paper,taking the Bajiang River Bridge as the engineering background,combined with the professional knowledge,the cantilever construction process of the bridge is monitored.The main contents are as follows:1.According to the design data and construction scheme,Midas civil is used to model and analyze the construction process of the Bajiang River Bridge;ABAQUS is used to establish a local finite element model to simulate and analyze the stress on the webs during the construction process.The deflection and stress of each construction condition are obtained preliminarily,and the control objectives of each stage are set;2.Follow up the construction process of the main bridge for construction monitoring,use the error between the measured data and the calculated value of the model to identify and modify the design parameters,then feed back to the finite element model.Use the prediction results of the grey system theory to verify each other,and guide the subsequent construction.3.The shear stress and the shear ratio of the corrugated steel webs in different sections are studied by measuring of the shear stress and the ABAQUS finite element model.And the reasons for the decrease of the shear ratio of the box girder webs with variable cross-section are analyzed;4.To meet the needs of the actual project progress,the influence of the overall temperature difference and temperature gradient on the deformation of the bridge is studied by the actual measurement and model analysis.In addition,the hydration heat in the hardening process of the bottom concrete is analyzed to find the main causes for the longitudinal cracks on the bottom slab of the main beam,which helps to solve the practical problems in the construction process.