Spatial Stress Test And Analysis On The Cable Saddle Of Extradosed Cable-stayed Bridge

As extradosed cable-stayed bridge introduced in our country, more than ten years and the structure characteristics, design theory and construction technology continuously explored by domestic engineers. It has preliminary owned the potential of being one of the mainstream bridges with its hardness and softness, beautiful linear and agile structure. The cable saddle of extradosed cable-stayed bridge is crucial bearing parts. It is the structure to provide direction diversion, anchoring for stay-cables and transform force to cable tower. The material, structure form, geometric alignment and transmission effect of the cable saddle will directly affect the stress state of the tower, stay-cables and the whole bridge badly.This paper has treated Changshan bridge as engineering background. Firstly, the static characteristic of Changshan bridge was analyzed by finite element software Midas/Civil. The Cable force value was extracted in both construction stage and use stage to provide data for the analysis of detail solid elements model. Secondly, the saddle areas correspond to the largest-forced cable and the bottom one spatial stress was analyzed with Midas/FEA. So that to get the theoretical stress state of the saddle and the surrounding concrete. Thirdly, the embedding scheme of the strain sensors in the cable saddle area was determined combined with the structure of the bridge tower and the arrangement the cable. So that to get the actual stress state of the saddle and the surrounding concrete. And put forward reasonable advice for the form of reinforcement through comparison to the theoretical value. Lastly, the structure form of saddle was transformed on the basis of the equivalence principle, so that to clear mechanical characteristics of multi-Steel pipes saddle and double pipes saddle. Through the comparative analysis, the conclusion was got. Understanding the stress state of cable saddle area in both construction stage and using stage is important guarantee of local area reinforcement of bridge tower. It also could provide bridge structure security and stay-cables systerm durability.In addition, the stress state is important reference of the model test of the bridge tower. So it has important practical significance.