Calculation And Analysis On Construction Of Suspension System Of Spatial Cables Self Anchored Suspension Bridge With Single Tower

With the progress of calculation theory and bridge construction technology, the spatial cables self-anchored suspension bridge with single tower is increasingly being applied to engineering practice. This paper uses Shangrao Bridge in Shangrao city, Jiangxi Province, as an example to conduct systematic analysis and construction technology discussion of spatial cables self-anchored suspension bridge with single tower.The calculation of hanger tensions and determination of cable shape are the most difficult parts of the design of spatial cables self-anchored suspension bridge. This paper mainly focuses on the reasonable stress state of the stiffening girder, to investigate the optimization of calculation method of hanger tensions. After the determination of the hanger tensions, we could use the numerical analysis of cable segments combining with the nonlinear finite element method to obtain the cable shape and the unstressed cable-length of the self-anchored suspension bridge. The method, due to its simplicity and ease of operation, can be extended to the calculation of the preliminary design of spatial cables self-anchored suspension bridge. This paper is going to verify the validity of the method by taking Shangrao Bridge in Jiangxi as an example.The key step in the construction of spatial cables self-anchored suspension bridge is the erection of the main cable. By Shangrao Bridge, this paper is going to study the follow problems:stakeout of main cable datum strand, determination of the transverse fixing angle, and elimination of cable strand bulging and twisting. Approximately, simulating the shape of the datum cable strand by parabola, this paper deduces the formula of elevation change of datum cable strand while the temperature, the horizontal span and height difference of the main cable change. On the basis of practical engineering, the reason of bulging and twisting of cable strand will be analyzed and several measures to eliminate them will be found. Then, combining previous project examples, this paper presents an easy method to determine the transverse fixing angle of the main cable clamp.During the transition of structural system of self-anchored suspension bridge, the optimization of hanger tension scheme affects the stress state of the structure, the safety of the structure itself and its construction. The key to optimize hanger tensions procedure is to calculate the hanger tensions accurately. Because of geometric nonlinearity during the process of hanger tension, the main cable presents large displacements, the hangers’ lengths between the main cable clamps and girder anchorage points have large changes which are much greater than the hangers’ elastic deformation. Such mechanical characteristic of hanger makes it very difficult to calculate the hangers’ tensions and lengths. This paper puts forward a method called equivalent nodal force method to calculate hangers’ tensions and lengths. The method is using nodal forces to replace the forces applied to the main cables and girder by hangers. Through iterative calculation, the bridge reaches equilibrium state, and the hangers’ tensions and lengths are determined.To sum up, the paper takes Shangrao Bridge in Jiangxi Province as an example, using the equivalent nodal force method to explore several issues for the transition of structural system of spatial cables self-anchored suspension bridge with single tower: optimizations of tension order and tension value, determination of procedure for incremental launching of the saddle, and analysis of the stress state of the structure in hanger tension process. The corresponding conclusions can provide references for the same type of bridges.