Research On Reasonable Completion State And Reasonable Construction State Of Cable-stayed Bridge With π-type Girder

Cable-stayed bridge is a complex of high-order statically indeterminate structure. The cable force have significant influence on the internal force of the structure, especially for cable-stayed bridge with prestressed concrete π-type girder.The cable force has great influence on the shape and internal force of the girder due to the features of its small section,light weight and small stiffness, so that the determination of reasonable completion state and construction state are critical in the theory of the structure analysis particularly.At the same time, the diversification of the construction method add new content to the bridge design.This paper takes Hunchun cable-stayed bridge as the engineering background,and considers the full framing method of casting construction and the characteristics of the π-type girder,and we complete the following work:(1)According to the characteristics of the small section and light weight of the π-type girder and the full framing method of casting construction,we add the girder displacement constraint conditions to the comprehensive algorithm including the minimum bending energy method, stress balanced method and influence matrix method put forward by the scholars.We get a synthesis method for determining reasonable completion state which is more suitable for π-type girder.(2)The integrated algorithm is used for determining reasonable state into a bridge to Hunchun cable-stayed bridge.The girder’s dead load bending moment of Hunchun bridge meet the requirements of the bending moment feasible region. It also has reasonable cable force distribution and the structure stress.(3)Considering some ways to determine reasonable construction state,we adopt a integrated algorithm based on suits the iteration method and influence matrix method,which is used to determine the reasonable construction of Hunchun cable-stayed bridge.(4)The construction process of cable tensioning and the construction scheme of Hunchun bridge by the integrated algorithm was determined.Finally,we determine the full framing construction scheme and the two stages cable tention,while tower construction,cable construction and beam construction simultaneously.The displacement of main girder in the reasonable completed bridge state is upward basically,which is convenient to the main girder linear adjustment during the process of the full framing construction,and overcome the disadvantage that the linear is not easy to control after the support girder dismantled.At the same time,the bracket is easy to dismantled,which reduces the difficulty of the contruction.(5)The cable force,linear deviation of main beam and main tower and the edge of main girder on stress value have a small difference between the actual construction into the bridge condition and the design value,which meet the accuracy requirement of the construction control.The results show that the effect of the construction control is better.At the same time,it shows that the method determining the rational state into a bridge and the rational construction state are reasonable.