Refined Analysis On Suspension Bridge At Initial Stage And Construction Stage

Suspension bridge has the most span capacity so far. This fact gives it an incomparable advantage on sea-channel projects and river-crossing projects. However, as the development of the calculation theory and the improvement of the calculation method, the safety factors fall down from 4.0 to 2.5. And as the span's increasing, considering the cost and the construction convenience, the component size can not be enlarged according to the proportion of the span, so maybe the emergency capacity of some members are lower. Hence, each construction stage and component needs to be analyzed more accurately to ensure the safety. Based on the traditional segmental catenary method, this paper analyzed the effect of the elastic extension caused the change of the deadweight density, self-load distortion caused elastic modulus loss and the temperature on the cable shape and inner force.There are two kinds of important and effective finite element calculation software on suspension bridge analysis, which are ANSYS and MIDAS. In this study, the two of them are used to analyze mega-span suspension bridge—AIZHAI Bridge on CHAJI highway. And the results are compared with the numerical method result which is calculated by FORTRAN program. The finite element results and the numerical method results match very well, namely the numerical FORTRAN program is proved to be accurate.In order to improve the wind-resisting performance, stiffened girder can be consolidated one by one. To verify the feasibility of this method to AIZHAI Bridge, two models are established to simulate, which are the hinged method and the consolidated method of the stiffened girders. And the analysis shows that there is little difference on the inner force of the main cable, but a significant difference on the stiffened girder. It endures even bigger inner force at some certain construction stage than the completion stage. However, the maximum stress is still under the material strength, so the girder consolidated method is applicable for AIZHAI Bridge.Cable saddle is an important component of the suspension bridge, which restricts the deformation of cable directly. In the previous design, without taking the saddle into consideration, engineers tended to take the ideal point as the only calculation basis. It is not accurate, and there is some influence for the elevation of completed bridge. In the last few years, people started to study the effect of the saddle, but so far there are still different opinions about how to revise the cable length at the saddle. On the basis of the existing documents, this paper puts forward an effective method to calculate the revised non-stress cable length.Based on the verified FORTRAN program, the article creatively puts the length-revision at saddle into the iterative program at each construction stage in order to keep a constant revised non-stress length. This paper is mainly concentrated on the effect of the saddle on the cable shape and preset at completion stage,cable finished stage and all other construction stage. Through FORTRAN program calculation and the comparison between the preset results from the ideal point,the tradition geometry method and the saddle iterative solution, a considerable effect of the saddle is found on the presets at all construction stages. Simulated by ANSYS, the same conclusion is proved again. Therefore the saddle must be taken into account in the practical engineering.