The Study Of Strengthening Bridge With Thin-Walled Box Girder

Along with the increasing application of box girder and thin-walled boxgirder of concrete in bridge building, there are more and more diseases in thistype of bridge during building and using. But the study of the causation of thediseases and strengthening methods is still on the march. Firstly this dissertationanalyzes the common causations of this type of bridge and the special causationof YongJiang Bridge in NanNing City based on the test data, and indicates thepoints of strengthening. The approach to the effective width of flange of boxgirder in English, Germany and China is analyzed contrastively, and thelimitation is put forward through building 3-D FEM model and studying thecrack distribution of YongJiang bridge, which is the primary reason to theappearing of cracks in the joints of flanges and webs. This paper research themethod of external pre-stressing particularly, which is more suitable forreinforcing the bridge with thin-walled box girder, including pre-stressing lose,stress increment in ultimate state, batched tension, calculation, anticorrosion andvibration damper and so on. The designing and comparing of reinforcing plansindicate that the external pre-stressing method can fit in with the need of thistype of bridge more better. On the base of this, this paper analyzes and compares the result of reinforcing effect with the method of finite element, and theanalysis data shows that the effect is well. Meanwhile, the optimization designof lengthways external tendon is put forward, which improves the reinforcingeffect.