Exploration Of The Finished State Of The Composite Beam Cable-stayed Bridge And The Method Of Realization

The structural analysis for perfectly finished state and reasonable construction state of cable-stayed bridge is the focal and key point of the design. It is a complex system, in which the two above factors are closely interconnected and can't be completely separated. The implementation of the reasonable state of the cable-stayed bridge mainly depends on three factors. The first one is structural system: bridge's vertical layout and main beam, king-tower and the dimension of cable-stayed cable and how to make the format are the mainly influencing factor for the rationality of design; The second one is the sampling of finished cable tension: under the condition of clear structural system the sampling of finished cable tension will greatly influence the reasonable finished state of the bridge; The third one is reasonable construction program with safety, economic construction management plan and the decision for construction parameter (control the cable's tension and the main beam's location elevation or shuttering elevation) included. The total aim is to implement the reasonable finished state of the bridge.With the development of technology and span enlargement of cable-stayed bridge, a kind of cable-stayed bridge that is composited by steel and concrete was developed widely. Now it is widely accepted as composite beam cable-stayed bridge. For composite beam cable-stayed bridge, besides has the general characters of common cable-stayed bridge, also has its own characteristics. This paper lays the research emphases on the characteristics of cable-stayed bridge, and the main work is as the following:1. The optimizing model of cable's force is established with a composite beam cable-stayed bridge as the background, adopting the stratified plane frame model to simulate the stress of composite beam. Then with the usage of zero displacement method and stress balancing method its perfectly finished state of the bridge is determined step by step. During the course of calculation, the conception of reasonable and constant load moment field was introduced. This moment field takes the influence effect of movable load which produced after the bridge was finished into consideration The method supplied the warrant for the adjustment of finished state of the bridge of cable-stayed bridge. Using step-by-step algorithm, taking the internal force of steel main beam as the main control objective, simultaneously taking the stress of tower, cable, and deck slab into consideration there come the results of more uniform cable's stress of finished state of the bridge, smaller moment of tower's bottom and more reasonable internal force. Moreover, while cable's stress was optimized, we also can exert the restraint about the deformation of main beam to object variable (each cable's force), and consequently make the stress and deformation of the structure under the condition of optimum cable's force comply to the requirement of design.2. Referring the construction method of the composite beam cable-stayed bridge, and comparing different programs of the cable tension, we can determine the construction flow of main bean's standard segment for the design. To analogy calculation of construction flow, this paper makes full use of the program of CREEP7, which is designed by our lab and can take geometric nonlinear, shrinking creep of concrete and contact nonlinear into considered. This kind of method is different from conventional backward analysis method; rigid sustainer continuous beam method and three (four) points zero method. It is a trial methodthat based on sequence calculation analysis and taken upper and lower margins' stress of main beam as control objective. This method effectively ensures the stress safety of steel beam and concrete deck slaps during the course of construction without repeated stretching cables. Taking both construction safety and construction object into consideration combined, this method finally works out the cable tension of construction in each phase, the making line position of main beam and consolidation location e...