| At present,super long span CFST arch bridges are all constructed with a cablestayed suspension method.The construction method has clear procedures,but the control points of each procedure are different.Based on the engineering background of Pingnan Third Bridge(main span 575m),this paper adopts the intelligent active control technology based on GNSS displacement automatic monitoring system and intelligent hydraulic control system.Research on the application of precision control in practical construction about tower deflection during segments suspension and arch rib chord concrete perfusion.This article introduces in detail the principles and methods of intelligent active control,control states and intervals,and the structure system and framework.The relevant parameters needed to be considered in intelligent active control are clarified,the calculation principle of the double hoisting point cable hoisting system considering side span action is deduced,and the variation law of the cable hoist is analyzed in combination with the real bridge.A method for drafting the initial tension of the wind cable under the geometric non-linearity of the structure is proposed to ensure the maximum rigidity under the passive control of the structure and achieve the goal of saving construction equipment investment.Using the influence matrix method,a calculation method for intelligent active load adjustment of towers based on the influence matrix method of the construction phase is proposed.Based on the calculation results,intelligent active control equipment and schemes are prepared.The measured results show that effectively control the deviation of the 200m-high Pingnan Third Bridge tower within 25 mm.Combined with the intelligent active load control technology of the perfusion process,from the perspective of structural displacement,stress and stress state,an evaluation idea of "optimal displacement and optimal stress" was proposed.The analysis and comparison of 24 perfusion schemes were carried out,and the optimal perfusion sequence is "first inside,then outside,last perfusion of the lower chord".Based on the analysis of the effects before and after the load adjustment,the effects of active load adjustment and equipment scheme investment during the pouring process are summarized.The method and principle of vacuum assisted sub-bin multi-stage perfusion of CFST arch bridge are put forward with reference to the pouring method of multi working faces in ring division of rigid frame arch bridge and the influence line in construction stage.The applicable conditions of the sub-bin multi-stage perfusion method and its differences from the other two perfusion methods in stability and structural performance are also discussed. |
