The Cantilever Assembly Error Analysis Of Continuous Steel Truss Bridge

In the past hundred years of development history, the steel bridge with it’s large span capacity, high strength, uniform material, good plastic and toughness, good weld ability, installation speed and other advantages, has made considerable progress in the transportation field. Among these steel bridges, the steel truss bridge with its own unique characteristics has being widely used in railway transportation. Because of the higher construction precision demand for steel truss bridge, any tiny error in the assembly process will lead to significant changes in linear, as a result, the final cumulative effect will affect the difficulty of the cross closure directly. Therefore, error identification and control through assembly process are particularly important. At present, the main error analysis methods for such a bridge at home and abroad are parameter sensitivity analysis method and parameter identification method which is based on random state.This article first review the basic of the finite element theory and its development, the significant meaning of the error analysis, and research status at home and abroad; and then discuss the basic principle of element birth and death function, which is used in the finite element software ANSYS to simulate the construction process. Next, introduce several parameter identification standards, and select the least squares method as the analytical method, so as to simplify the calculation formula. Then use this method to revise the theory calculation values of main construction phase on some bridge, therefore, we can get corrected values, which are close to the measured linear values and vertical rod corner, at the same time, demonstrate the rationality of the corrected values. On this basis, the pure geometric assembly error in each assembly section can be solved.Through analyzing the calculating result and some field data, it shows that:(1) The least squares method can satisfy the precision requirement of the theoretical value correction, which makes the revised theoretical values and the front assembled section vertical rod nearly the same as measured values;(2) After rationality checking, it shows that the selected parameters identify values are basely meet the rationality requirement of assembly error;(3) Based on the revised theory values, the pure geometry assembly error values of the single step section can be calculated.