Study On Reasonable Construction State Of Long-span Railway Cable-stayed Bridge With Low Tower

Low pylon cable-stayed bridge is a new structure system,which has the characteristics of superior structural performance,good economic benefit and good aesthetics.In the construction process of low pylon cable-stayed bridge,the system is constantly changing.In order to achieve the goal of bridge completion and ensure the safety of the structure during construction,it is necessary to study its reasonable construction state.The reasonable completion state is the premise to ensure the reasonable structural stress of the low pylon cable-stayed bridge during the completion and operation stages.In the structural calculation,the reasonable completion state should be determined first,and then the construction of the reasonable completion state should finally meet the requirements of the reasonable completion state.With the help of Midas/Civil finite element software,this paper studies the reasonable construction state of Panzhihua Jinshajiang Bridge of Cheng-Kunming Railway,mainly carrying out the following work:(1)The development situation of low pylon cable-stayed bridge at home and abroad is introduced,the existing problems in the development of long-span low pylon cable-stayed bridge are summarized,and the reasonable construction state and reasonable completion state of low pylon cable-stayed bridge are summarized.(2)The theory of determining the reasonable completion state of the low pylon cable-stayed bridge is studied.On the basis of the analysis and summary of previous research results,the feasible zone of constant load bending moment of the main beam of Jinshajiang Bridge is obtained by using the stress balance method,and the reasonable completion state of the bridge is determined by using the Midas/Civil unknown load coefficient method.(3)The calculation method to determine the reasonable construction state of the low pylon cable-stayed bridge is studied.Using the unknown load coefficient method which considers the construction stage,the reasonable initial tension and the secondary tension of the whole bridge are calculated respectively.Based on the reasonable construction status,the stress and deformation of the structure during the construction process are analyzed in combination with the field practice.At the same time,the force analysis is carried out to ensure the safety of the bridge during the operation stage.(4)According to the objective conditions of the Jinsha River Bridge site appears in the actual construction cannot be carried out in accordance with the design of a given construction sequence of the case,this paper puts forward the side span cast-in-place period of asymmetrical cantilever construction of two kinds of schemes,are studied using these two schemes after pouring the side span cast-in-place section on stress and displacement of maingirder,the girders of suspension cable force influence degree,to identify the better of a plan to guide the actual construction.Through the research on the asymmetric cantilever construction in the side span cast-in-situ section of the symmetrical structure of Jinshajiang Bridge,the practical construction problem of this bridge is solved successfully,and the safety in the construction process is ensured,which provides a reference for the follow-up construction of this kind of bridge in the aspect of asymmetric cantilever construction.