Bilateral Box Girder Arch Tower Cable-stayed Bridge Shear Lag Effect And Construction Control Study

Right branch of Maanshan Changjiang River Highway Bridge is domestic first three concrete arch bridge tower cable-stayed bridge, the bridge tower of the beam synchronization construction schemes for the first time in China, and there is no related information available at the present stage, at the same time the main girder of the bridge width is 35.3 m wide bilateral box girder, domestic aiming at this kind of bridge shear lag effect and construction control research is less, based on the engineering background, the main research contents and results are as follows:(1) Using MIDAS software to establish the space finite element model of the bridge tower construction, analyzes the stress and deformation of the main tower, through the calculation and the measured result, the tower and beam synchronous construction compared the not synchronous construction scheme, construction process of tower cross the bridge to the outside to the maximum tensile stress and transverse bridge tower bridge displacement is increased, but the range is limited, cross bridge tower bridge to the maximum tensile stress in a safe range, tower beam synchronization construction scheme of structure has certain adverse effect, but is feasible.In the tower beam synchronization construction process, through the parameter analysis, determine the tower beam synchronization construction horizontal force actively in the process of applying the position and size, improved the bridge tower.(2) Using ANSYS software to establish the main girder and local model, through the parameter analysis shows that bilateral box girder roof thickness increase 5 cm will reduce average compressive stress of roof, floor increasing average compressive stress roof thickness reduce 5 cm to the average stress of main girder roof and bottom.Roof thickness reduce 5 cm will make the roof by the positive shear lag effect into the negative shear lag effect.Girder vertical web thickness increased or decreased by 5 cm to girder roof, base shear lag effect is limited. Setting transverse diaphragm will make the main girder normal stress distribution is more even, reduce the shear lag coefficient peak.(3) The main girder cantilever construction process, has been tensioning of the complete suspension cable force with seven beam is close to the period of construction, following after smaller than its impact on the construction of the section.The measured cable force hanger forces are slightly larger than the theory, the temporary load too much with that of the actual construction process, the overweight.(4)The main girder cantilever construction process of the main girder elevation and cable force causes of error and correction calculation model, and will work with the girder elevation related information as input samples, the construction of the elevation error as the output data, and use the matlab neural network toolbox of modified BP neural network, between the input data and output data for training, establish contact, get a relevant model for linear prediction analysis, through the comparison with experimental data and analysis, validate the correctness, and the prediction results feedback to the main girder vertical mold elevation, finally achieved the closed smoothly and line is fluent, girder, girder and pylon cable force is reasonable, the bridge tower deviation is normal.