Abstract
Six prestressed concrete beams (PC beam) were used for evaluation, consist of four post-tension beams (PC-O) and two pre-tension beams (PC-R). In order to investigate the effect of crack on prestress loss and bending capacity after long-term exposed, prestressed concrete beams were pre-crack and then exposed to marine environment. Experimental work was carried out to evaluate PC beams performance after long-term exposed. In addition, visual observations and load bearing capacity test was carried out. Furthermore, evaluation of prestress loss conducted using three-point loading bending test and the remaining tendon forces in the beam were determined using Crack Re-opening Method. The experimental results revealed that prestress loss was increased due to corrosion of strand/wire which affected by the pre-crack on the prestressed beams. Approximately a prestress loss around 26% and 30% was recorded for post-tension and pre-tension beams respectively.
Highlights
Reinforced concrete and prestressed concrete structures exposed to aggressive environments, cracks play an important role in accelerating the corrosion process [1]
Longitudinal cracks pattern was found along the beams with maximum crack widths for PC-O-3 showed larger than PC-O-2 with 2.2 mm and 0.5 mm, respectively
The probable explanations why specimen with pre-cracked cracks occurred earlier, because higher of prestress loss make prestressed concrete starts to behave like a reinforced concrete beam when the value of the flexural moment is well beyond the cracking moment
Summary
Reinforced concrete and prestressed concrete structures exposed to aggressive environments, cracks play an important role in accelerating the corrosion process [1]. High strength prestressing steels show a far more sensitive reaction to corrosion attack than reinforcing bars. The loss of an equivalent sized reinforcing bar have not given a more significant effect on the structural capacity compared if the loss of one prestressing strand or wire will be. Several researchers found that corrosion of prestressing steel reduced in flexural capacity. If one 12.7 mm diameter prestressing strand is assumed to fail in the 100% U PS (prestressed based on nominal strengths requirements) section the nominal flexural capacity is reduced by 13.5% [3]. Bridge was assessed to be up 10% loss in live load capacity in the individual beam which has lost the two strands [4]
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