Kenta TAKEDA
Numerical Evaluation of the Residual Strength of Pre-tension PC Girder Affected by Chloride Attack
Kyuichi MARUYAMA and Yasushi TANAKA
Prestressed concrete (PC) structures which were constructed in 1960's and 1970's are now suffered from chloride attack in Japanese coastal areas. However, little research work has been done about the residual strength of corroded PC structures. In this research, results of loading tests of pre-tension PC girder, which had been in service for about 35 years near the Japan Sea, were selected as a research object. The strength of the PC girder was evaluated with Finite Element (FE) analysis.
Firstly, based on the measurement results of weight loss of PC strands, we conducted FE analysis to simulate loading tests. As a result, we succeeded to simulate loading test in FE analysis by considering precise distribution of corrosion. In addition to that, the reduction of mechanical properties should be considered in stress-strain relationship used in FE analysis. It was found that both fracture mode and structural performance of girder were estimated accurately in FE analysis.
Secondly, we evaluated the strength of girder focused on internal cracks. We assumed that PC strands have been completely melted if the distance from crack surface is smaller than maximum size of coarse aggregate. It is cleared that the locations where PC strands are corroded are estimated appropriately from the internal cracks. Therefore, and FE analysis.
Finally, we have tried the strength evaluation with FE analysis focused on external cracks of girder. We predicted internal cracks from external cracks. Then, remaining position of strands are estimated from the way described above. Because the prediction of internal cracks does not have accuracy, estimated structural performance is somewhat different from experiment.
Technical knowledge established in this research should be used only in pre-tension PC girder which have small diameter tendons. For PC girder which have large diameter tendons or post-tension tendons, further studies are necessary.
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