Considering The Large-span Of The Construction Process Reinforced With Concrete Arch Bridge By Force Performance Research

Luobuxi Bridge is a large span reinforced concrete arch bridge with stiff skeleton of concrete-filled steel tubes on Yichang-Wanzhou Railway. It's calculation span is 178m. The arch ring include two separated arch ribs which 5.057°inward and connected by several transverse braces. As it is passed by a series of system conversion of construction, the construction process of the bridge is very complex. Mechanical behavior of Luobuxi Bridge was analyzed by 3D finite element method. The major work is summarized as follows:1. The mechanical behavior during the construction of the arch which includes erection-joining of steel framework and pressure grouting of concrete in the steel tube has been studied, and two pressure grouting orders of the concrete in the steel tube has been compared. The results show that the stress level of the entire stiff skeleton is low; influence of pressure grouting orders of the concrete in the steel tube is small.2. The mechanical behavior during the construction stage of the stiff-skeleton outer concrete (SSOC) has been studied. Moreover, the intensity of SSOC with two construction methods in which one is with equal piece-wise and the other unequal piece-wise has been compared. The results indicate that the stiff-skeleton outer concrete with the two methods is both safe; moment in the construction method with unequal piece-wise is small, and the stress curves are smooth.3. Through studying the influence of disconnected crown frame of arch to holistic mechanical characteristics, it can be found that frame connected or not is influential only in the range of frame, is no effect on other regions.4. The whole bridge's mechanical behavior was analyzed under various design loads. The results show that stress level of arch, transverse braces, column and frame are low, and they are safe;5. Based on the analysis of whole bridge, local stress distribution of the arch-foot and the skewback was studied. The analysis results show that the slower the change of arch-foot stiffness, the lower the peak stress.The results of this thesis has been applied to the design and construction of Luobuxi Bridge, and the computational theory and investigation method can be a reference to the other same type bridges.