Linear Control Of Arch Rib Of Long-span Steel Box Handle-basket Arch Bridge And Analysis Of Influencing Factors On Accuracy

Most of the arch rib installation of the large-span steel box basket-handling arch bridge adopts the unsupported cable hoisting method.This construction method requires accurate calculation of the anchor cable force and pre-arching degree,and analysis of the factors affecting the arch rib hoisting accuracy to ensure that the internal force and appearance of the arch ribs are close to the design requirements after the arch bridge is completed.In recent years,more and more scholars have conducted a series of studies on the control of the arch rib alignment.However,in the traditional construction control system,the research on the factors affecting the arch rib hoisting alignment accuracy needs to be in-depth.In the arch rib alignment prediction method,when considering the impact factor,it is single and independent,showing a lack of consideration of time and space portability and the lagging nature of the impact factor,resulting in low accuracy of construction prediction results.To this end,a certain bridge in the west was selected as the research object of this thesis,and the following work was done:1)Aiming at the current arch rib linear predictive control method that lacks consideration of time,space portability and the lagging nature of the impact factor,the arch rib hoisting linear predictive control model based on the polynomial distributed lags model was proposed,and the research on double prediction of spatial coordinates and cable buckle force for arch rib segment hoisting was carried out.2)The establishment of the prediction model requires the analysis of the transmission law of arch rib hoisting errors and the common factors affecting the arch rib alignment.The calculation results show that temperature changes,cable buckle force errors and pylon deviation have significant effects on the arch rib alignment of a bridge in the west,and they are important factors in the arch rib alignment predictive control.In addition,in the feasibility analysis of the temporary anti-thrust system of a bridge in the west,the proposed construction method of "pre-tensioning temporary tie rods" will cause the arch rib to move upward,so the pre-lifting amount of the arch rib was optimized to ensure the accuracy of the coordinates after arch rib pre-lifting.3)Considering the two influencing factors of temperature change and cable force error and their hysteresis effects,the linear relationship between the linear deviation of the arch rib and the temperature change and the cable force error was theoretically deduced,and the equation of the linear predictive control model for arch rib hoisting based on the polynomial distributed lag model was established.4)The econometric analysis software EViews was used to solve the polynomial distributed lags prediction model equation of each arch rib control point of a bridge in the west.The model can accurately predict the linear change of the arch rib,has strong timeliness and accuracy,and can avoid the establishment of a more complicated temperature field effect and cable force error calculation model in the finite element model.The comparative analysis of prediction values and relative errors with the MGM(1,2)model shows that the PDL prediction model is more superior in algorithm,accuracy and actual operation,and can highlight the changes in the overall trend of the arch rib linear in the time series,and has the ability to analyze strong interference factors.