Study On The Key Problems Of Construction Control Of Jiya Watercourse Bridge

Extradosed cable-stayed bridge is a bridge which is intermediate between traditional cable-stayed bridge and continuous beam bridge. Due to its superior structural performance and good economic indicators, this bridge type achieved great development in our country. In the engineering background of Jiya Waterway Bridge, the paper has researched the geometric linear control and cable force control in construction control.Bridge geometric linear control is divided into: the main tower deviation control, the main beam axial offset control and the main beam vertical deformation control. In this paper, the study of geometric linear control, focus on the main beam vertical deformation control. This paper has studied several factor which have relatively large impact on the vertical deformation of the main beam, they are elastic modulus of concrete, concrete bulk density, loss of prestressing steel reinforcement, temperature effect, creep effects and temporary construction loads. By compared the results of the theoretical analysis and experimental data analysis, it finds that the vertical deformation of the main beam is sensitive to factors: concrete density, temperature effect, creep effects and temporary construction loads.In cable force control study, the paper has used the method of frequency to calculate the cable force. In order for the cable force calculation results are closer to the true value of the cable force, this article has used finite element method to calculate the cable force in accordance with Hamilton principle. To prepare the finite element calculation program This paper deduced the stiffness and mass matrices of the cable vibration. Factors influencing cable force calculation results are: length of stay cable, cable line quality, cable boundary conditions, cable flexural rigidity. This paper has analyzed the factors and found that the results are sensitive to length of stay cable, cable line quality while cable boundary conditions, cable flexural rigidity has a certain impact on them.The cable force control divided into: initial tension control in construction stage, cable force uniformity control and entire cable force control. In the initial tension control in construction stage, this paper has used the difference iterative method. It founds that the convergence rate of calculation process is quickly by using this method. In the cable force uniformity control, this paper has used graded tension method. Upon examination of the measured data, it confirmed the validity of this method in cable force uniformity control.