Studies On Construction Control Calulation And Control Measures Of The First Hejiang Yangtze River Bridge

The construction of cocrete filled steel tube (CFST) arch bridge with long span is divided into many working procedures, which are completed step by step. The construction process is complex and long. So, the rigorous control of construction is the guarantee of achieving design objective of the CFST arch bridge. Taking Hejiang Bridge as an instance , many problems on construction control calculation and control measures for CFST bridge are discussed in this paper, including: the analysis method of simulating construction phase, calculation of stayed-buckle-cable forces, calculation of pumping concrete, calculation of bridge pile surface construction, analysis on the error in construction control, sensitivity analysis of parameters and parameter identification, control measures. The follows are main works:â‘ In order to achieve the control accuracy requirements, propose a method of solving the cable force based on Midas/civil unknown load factor in the rib lifting stage, and three kinds of cable force projects was calculated with this method, the project which the cable was tension one time only before cantilever, and to adjust cable tensioon when closure is more reasonable after a comparative analysis. In stage of calculation about concrete was filled in tube, analysis the stress and lineshape of arch rib, in stage of calculation about bridge pile surface construction, analysis the initial tension and length of suspender. Because of the high accuracy, it can be used in construction control credibly.â‘¡In order to diminish error at process of construction, The main factors that affect the error of construction control in the constructing process of CFST arch bridge are analyzed. According to the node displacement, deduced the basic equation which was used to parameters identification based on the principle of least squares method , and was applicated to Hejiang bridge.â‘¢Studing on control measures of Hejiang Yangtze River Bridge, including: modify the line shape of arch rib, modify the temperature when closure, displacement control of button tower, the cable force influence on line shap of arch rib when concrete was filled in steel tube, and optimizing sequence of pumping concrete. The results show that: there are adjusting projects which combines prop upper chord and pressure top arch for the temperature higher than the base temperature, and there are adjusting projects which combines draw lower chord and prop upper chord for the temperature below the base temperature; The fine-tuning the cable force have less influence on bridge displacement and on bridge internal force at the process of concrete pumping, So, the cable force does not adjust at the case of keeping proper cable force; After study, considering the construction stability and steel tube stress, determine the best sequence is outside first and inside last, upper chord first and lower chord last.