Safety Evaluation of Reshoring through Structural Testing of Early-Age Reinforced Concrete Beams

Significant concerns of reshores lie in their safety when shores are being replaced while the construction load of the upper floor is applied. Reinforced concrete (RC) beams at early ages were tested to investigate the concerns. Tests on cylinder specimens showed that the compressive strengths and elastic moduli of early-age concrete are reliably predicted using the equations in KCI code and, therefore, the nominal strength and stiffness can also be predicted for RC beams with ages other than 28 days. The RC beams of 2 or 3 days old showed a shear-compression failure and the RC beams of 7 or more days old showed a typical flexural behavior. Because the shear strength of RC beams is more affected by the compressive strength of concrete than their flexural strength is, the shear capacity needs to be checked in case of reshoring. Tests also found that beam-column joints have sufficient stiffness even at early ages and the joints can be safely assumed to be fully restrained regardless of the concrete age. From the test results, it was drawn that reshoring at 5 days of concrete pouring is safer than keeping the shores by 55%.

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