Theory Research On Construction Control Of Concrete Cable-Stayed Bridges

With employment of high strength material, improvement of structural analysis, and development of construction ways, it is a rapid developing period for cable-stayed bridge in the 90's, 20th century. With the span's increase and diversity of structure, cable-stayed bridge has begun to compete not only with suspension bridge in large span, but also with other bridges in middle-small span. Increasesof span and variety of bridge have caused many tasks to construction control of cable-stayed bridge. This paper putsemphasis on some key questions of construction control of cable-stayed bridge, with main content and conclusions as the following:1. Aim at optimization on multi-objects and multi-restriction of construction control of cable-stayed bridge, Method of satisfying trade-off and Method of Synthesized Parameter are united to get the solution. The character of this way is to aggregate multi-objects and multi-restriction through aggregate function. Problems of multi-objects and multi-restriction are transferred to optimization problems of single-objects and single- restriction. Lagrange Multiply Method is used to transfer the question of single-objects and single- restriction to that of none extremum, then the answer is gotten. Method of Satisfying Trade-off and Method of Synthesized Parameter are practical methods to solve question of optimization on multi-objects and multi-restriction in real projects and they have wide applied cost.2. There are many ways to confirm reasonable finished state of cable-stayed bridge. However, trail method is usually used in adjustment of cable strength. Based on none-distortion pre-strain, this paper contributes design of cable strength to none-distortion pre-strain. Multi points and internal force are selected as control objects, In finished state, these control objects are similar to that of expected. When pre-strain is added, the cable is not cut off, and it is consistent with real state.3. Based on Methods of Influence Structure, through analysis of course during the cable being tensioned, mathematical optimization model on jacking course is set up. Meeting all the conditions of jacking tool's transitionstate carrying capacity, internal force, and displacement constraint, this method arrives pre design state and solves the question of cable in construction period.4. Optimization function of multi-objects and multi-restriction has been found to adjust errs of cable-stayed bridge in finished state. Method of Satisfying Trade-off and Method of Synthesized Parameter are adopted. Through computing example, correctness of program and feasibility of this method is validated. As a matter of fact, this model not only fits the adjustment of cable-stayed bridge in finished state, but also applies to construction control of suspension bridge, arch bridge. It has important reference value for similar questions.5. Cantilever construction or full framing is commonly used to construct cable-stayed bridge with cradle. It is the first time for Slide Die Carrier to be used in main beam, GongHe cable-stayed bridge. This method brings many new tasks to construction control. For this construction way, this paper brings forward a concept that "single-support, single-suspension" system is adopted before casting concrete; and "single-support, double-suspension" system is adopted after casting concrete. This scheme solved safety problem properly in construction. According to character of this method, a suit of construction scheme is established. Gonghe cable-stayed bridge' s buildup proved feasibility of this method.