Research Of Construction Control Of Concrete-Filled Steel Tubular Arch Bridge With Long Span

The construction of CFST arch bridge with long span is divided into many working procedures, which are completed step by step. The construction process is long and complex. So, the rigorous control of construction is the guarantee of achieving design objective of the CFST arch bridge. Taking Nanpu Bridge (FST bridge) in Chun-an county as an instance, many problems on construction control technique for CFST bridge are discussed in this paper, including: the analysis method of simulating construction phase, construction monitoring technology, calculation of stayed-buckle-cable forces, allotting deadweight of pumping liquid concrete, analysis on the inflection of shrinkage and creep of core concrete in steel tube, analysis on the error in construction control, sensitivity analysis of parameters and parameter identification.The technique of "birth and death element" is applied to the simulation analysis for the construction process of CFST arch bridge, which makes modeling job very simple in orderly-erecting analysis and inversely-erecting analysis, and data transferring very easy between them. What's more, the order flows about the simulation analysis is programmed based on ANSYS software, which makes simulation analysis rule and simple.The optimizing theory is introduced to the calculation of the stayed-buckle-cable forces in the process of segment hosting construction of the steel-pipe arch and adjusting construction error. The calculated optimum cable forces with high precision can always guarantee the inner forces and the structure distortion in safe state and ensure the line shape of the arch according with design objective.The peculiar mechanical character about pumping liquid concrete is discussed. Based on the supposition that the ability of transferring hydraulic pressure of liquid concrete is orthotropic and the friction forces exists between concrete and steel tube, the pressure formulas of liquid concrete and the allotting formulas of deadweight are reasoned out. A new method is brought forward for allotting deadweight of liquid concrete during simulation analysis in pumping-core-concrete construction phase, which improves the calculation precision.The calculation modes of the coefficient of shrinkage and creep of the bulgy core concretein steel tube are discussed. Based on a few reasonable hypotheses and the stress-strain relation of concrete acquired by the "adjusting valid modulus depending on load time" method, a compact formula is reasoned out, which is applied to calculate the equivalent elastic modulus of the bulgy core concrete considering the affection of shrinkage and creep. So, the analysis of the affection on CFST arch bridge by shrinkage and creep can be progressed by pole-girder FEM, further more, the analysis precision is quite high.The main factors that affect the error of construction control in the constructing process of CFST arch bridge are analyzed. The half analytic formula is reasoned out, which is applied to the sensitivity analysis on design parameters. Through the sensitivity analysis of design parameters in constructing phase of Nanpu bridge, the main design parameters are confirmed. Based on this, the real value of parameters are identified by least square method, by this token, the error of design parameters can be eliminated in the process of construction control.