Takumi NAKAZAWA
Experimental Study on Shear Strength of Pre-tension Hollow Girder Degraded by Alkali-Silica Reaction
Kyuichi MARUYAMA and Yasushi TANAKA
Alkali-silika reaction(ASR) is one of the concrete degradations. Recently, there are remarkable number of prestressed concrete bridges deteriorated by ASR . Elucidation of the damage mechanism and establishment of a damage assessment method due to deterioration are required. In this study, The objective of this study is to clarify the shear strength and failure mode of the PC hollow girder which is degraded due to ASR by using an experimental study focusing on shear strength. Specimens were made to simulate real size PC hollow girder. Specimens were cured in accelerated condition to be deteriorated by ASR rapidly. Testing parameter is the amount of free expansion by ASR, i.e., 2000¦Ì(A-2000), 3500¦Ì(A-3500), 4500¦Ì(A-4500), and sound specimen.
Cracks were caused by the progress of ASR in each specimen. The observation of crack patterns cleared that cracks shaped hexagonal due to ASR. Moreover, the number of cracks increased with the increasing period of ASR acceleration.
In the loading test, it was confirmed that the shear strength of PC beam is lowered as ASR reaction becomes advanced. In case of sound specimen, the bending cracks occurred before the shear cracks in loading test and many bending cracks were observed. In case of A-2000 and A-3500, shear cracks occurred before bending cracks in loading test, and few bending cracks occurred. All of ASR specimens failed in shear compression failure. It was consistent with the failure mode estimated from JSCE specifications by comparing the strength of each failure mode. Diagonal tensile failure occurred in sound specimen. It is supposed that the maximum load is reduced due to the loss of shear transfer mechanism by the diagonal crack progress at web part
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