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http://dx.doi.org/10.12989/cac.2018.22.2.133

Behavior and stress check of concrete box girders strengthened by external prestressing  

Zhang, Yu (Department of Bridge Engineering, Tongji University)
Xu, Dong (Department of Bridge Engineering, Tongji University)
Liu, Chao (Department of Bridge Engineering, Tongji University)
Publication Information
Computers and Concrete / v.22, no.2, 2018 , pp. 133-142 More about this Journal
Abstract
The deterioration of existing bridges has become a major problem around the world. In the paper, a new model and an associated stress checking method are proposed for concrete box girders strengthened by external prestressing. The new model called the spatial grid model can analyze all the spatial behaviors clearly by transforming the box girder into discrete orthogonal grids which are equivalent to plate elements. Then the three-layer stresses are employed as the stress checking indices to evaluate the stress state of the plate elements. The initial stress check before strengthening reveals the cracked and potential cracking areas for existing bridges, making the strengthening design more targeted and scientific; the subsequent stress check after strengthening evaluates the strengthening effect and ensures safety. A deficient bridge is selected as the practical example, verifying the accuracy and applicability of the proposed model and stress checking method. The results show that principal stresses in the middle layer of plate elements reflect the main effects of external prestressing and thus are the key stress checking indices for strengthening. Moreover, principal stresses check should be conducted in all parts of the strengthened structure not only in the webs. As for the local effects of external prestressing especially in the areas near anchorage and deviator, normal stresses check in the outer and inner layers dominates and local strengthening measures should be taken if necessary.
Keywords
bridge strengthening; external prestressing; spatial grid model; stress check; concrete crack; principal stress;
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Times Cited By KSCI : 5  (Citation Analysis)
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