The Research Of Construction Control Of Three Main Truss Steel Bridge With Rigid Cable

Steel truss is a traditional structural style,with the development of smelting technology from 19th century,steel is more and more used in bridge construction. Since 1937,the famous bridge expert Mao Yisheng responsible for the design and supervision of the construction of Qiantang River Bridge,the steel truss bridge in China has been rapid development.Steel components can be mass produced,easy transported and quickly assembled.So,steel bridge can be constructed and repaired quickly,it has great advantages in the repair aspect.During the construction of the steel truss bridges,the internal force and deformation of structure will change as the main truss extends and force-displacement in horizontal and vertical direction,and moreover some uncertain factor such as temporary load,solar radiation and the change of temperature affect the internal force and deformation of structure.So we must take action to forecast the internal force and deformation to accord the quality and the line-shape of the completed bridge with the designed.Dongjiang bridge is the first double-decker highway bridge in China.It is the first time use for three main truss steel bridge with rigid cable in freeway bridge construction.So,this bridge has new topic in the aspect of force analysis and construction control.The paper does the following work with Dongjiang bridge in the background:Firstly,the paper discusses the meaning of the construction control for cantilever assembly steel truss bridges and the actuality development in this area.Then introduces rationality and advantages of unstress state construction control theory and the method of the calculation for ideal state in every construction stage.Secondly,the paper establishes the computing model of Dongjiang bridge with the guidance of unstress state construction control theory.And it calculates and forecasts the internal force and deformation in every construction stages,and the result is satisfied.Discusses the method of closer construction of main truss and rigid cable based on unstressed length and unstressed curvature.Solutes some key problems such as internal force adjustment in the horizontal direction,anti-collapse calculation of structure and the safety of temporary piers. The research indicates that unstress state construction control theory makes the calculation easy.It can intuitively build link between completed bridge and every construction stages and makes the internal force state and line-shape automatic approximate the design requirements.