Destructive Test Research Of In-Service Prestressed Concrete Changing Section Wide Hollow Slab Bridge And Shear Strengthening Study Of External Prestressing

In mid-1990s，the wide hollow slab bridge with PC variable cross-section have beenwidely used in the construction of highway bridge in China because of its superior economicperformance,and rapidly become popular in the cities of Zhejiang. However,with theoperation of bridges, its structural defects,such as large hollow rate,thin wooden partition,poorstructure resistance,are exposed gradually. And it makes the hollow plate disease becomingincreasingly serious. In this paper,we detailedly surveyed the using situation of wide hollowslab bridge with PC variable cross-section which is in service in Jinhua City.The results showthat the diseases of this kind of bridge are serious,and the type of these diseases has a certainuniversality.Based on the dissection test of beam and flexural and shear destructive test of widehollow slab with PC variable cross-section of Baiyangdu highway cross-rail interchange inJinhua City,we did a simulation analysis of the destructive test by ANSYS software to contrastand analyse the ultimate capacity of flexural and shear,force performance of structure anddiseases situation of tested hollw board,and analyse the causes of longitudinal cracks of thehollow slab bottom in detail.In view of the serious shortage of shear capacity of this type ofbridges,we propose a strengthening method by using vertical prestressing to reinforce theinclined section of hollow slab.The analysis results show that,the flexural capacity of destructive test and ANSYSanalysis are both greater than the result according to specification calculation.But the hollowslab has many initial ctacks whice are not visible and result in the initial flexural stiffness ofthe hollow slab is relatively low.Shear capacity is similar to the calculation result ofspecification,but is less than the maximum shear which is analyzed by SAP2000when bridgeis under normal operation. And we found that the reinforcement ratio of web diagonal sectionis insufficient by comparing the failure modes of the hollow slab.Through the comparativeanalysis of various parameters before and after reinforcement of hollow slab,show that thisreinforcement method can significantly improve the shear capacity,stiffness,ductility andcracking load of oblique section,and has a certain value. In this paper,we discussed the method of using ANSYS software to model and analyz thedefects of hollow slab,which can be used as an effective method to accurately simulate thebearing capacity of wide hollow slab bridge with PC variable cross-section.And it is veryhelpful to understand the present situation of bridge,reduce he cost of bridge detection andimprove the strengthening effect.