Study On Construction Monitoring And Mechanical Performance Of Extradosed Cable-stayed Bridge

The extradosed cable-stayed bridge is a kind of new bridge between the ordinary cable-stayed bridge and the traditional beam bridge.It is complex to control the stress and linear of the variable construction process,thus construction monitoring was needed to ensure the security and quality.A full-bridge truss model was established by using the finite element software Midas Civil to simulate the working conditions in the construction processfor getting the internal forces and deflections of the relevant control sections under different operating conditions.On this basis,the thesis studies the influence of construction sequence change and construction scheme change.This thesis summarizes the key problems in monitoring-stress and linear control,and concludes a simple calculation formula of the single stretching construction technique of extradosed cable-stayed bridge,which is verified by actual monitoring.The thesis analyzes shear lag effect of wide bridge in detail by establishing solid model by Midas FEA to simulate each working condition in the construction phase as well as establishing the corresponding truss model.The results show that the effect of transverse prestressed steel to the longitudinal stress of the control section from diaphragm plate is very small;the shear lag effect of control section caused by the concreting is also not obvious;while the longitudinal prestress force is liable to the position of the measuring point and the tension of the stay cable is likely to cause local stress increased obviously as well as shear lag effect;In the stress measurement of wide box girder,the method of solid modeling should be adopted to obtain the theoretical value of the measuring point.The hanging basket is closely related to the construction of wide box girder,which acts as a support system of cast-in-place cantilever method.Hence this thesis conducts a special study to the hanging basket.Through the establishment of the finite element model,the stress and deformation of the hanging basket under different working conditions were analyzed and the checking of security against overturning was also carried out.The results show that the construction basket is safe and reasonable.Dynamic and static load test is a direct way to study the load-bearing capacity of bridges.By formulating the load test program of extradosed cable-stayed bridge,the thesis analyzes the test data and studies the stress performance of cable-stayed bridge,which provides a basis for the safety and rationality of designing the bridge.