Determination Of Reasonable Construction State And Construction Controlling Of Long-Span Concrete Filled Steel Tube Arch Bridges

The main aim of long-span concrete filled steel tube arch bridge construction controlling is to make the line shape and the internal force accord with the demand of the design to the largest extend when the bridge is finished as well as to ensure the security during the course of construction. Many factors influence the precision of bridge construction controlling, such as parameters of structure, technologies of construction, monitor and measurement during construction, the model of structure for calculation and analysis, temperature, shrinkage and creep of concrete. During the construction, stress and line shape are very important control factors. This article introduces the history, importance and developing tendency of bridge construction controlling, detailedly expounds the main content, principles, methods and the influencing factors of construction control, and puts forwards a construction monitor means corresponding to construction characteristics of concrete filled steel tube arch bridges. Based on the Maocao street half-through concrete filled steel tube steel frame tied arch bridge, this paper makes research on the reasonable construction state for the long-span concrete filled steel tube steel frame tied arch bridge and brings forward a way to confirm finished bridge state and the corresponding reasonable construction state. At the same time, aiming at the cable rope lifting construction technology of the main arch rib, the paper advances a forward-iteration method to ensure the cable tensile force. The very method is used to make certain reasonable construction state on cable-stayed bridge. This method with the application of bridge design and construction monitoring system (BDCMS) can confirm cable tensile force through choosing suitable controlling parameters. The way of ensuring finished bridge state is firstly to model the main arch rib in one step based on the adjustment line shape, then carry through subsequent construction steps until the bridge is completed. It is used to estimate and analyse the finished bridge state of Maocao street bridge, and its feasibility is verified. According to the top and below edges stress controlling conditions of main arch rib, the article puts forward the concept of "feasible field of main arch dead load moment"and the way of calculating and checking the main arch dead load stress, which provides powerful basis for the adjustment of finished bridge state. After the determinination of the finished bridge state, the article comes up with forward-iteration method confirming reasonable construction state of concrete filled steel tube arch bridges. Comparing with backward-iteration method, this method only needs forward-calculation, which equips three advantages, easy application, clear thoughtfulness and better effect.