Prestress Loss of Lower Flange Concrete of Preflexed Beams during the Storage Period and its Influence on Load Deflection Behavior

Abstract

Prestress loss of lower flange concrete due to creep and shrinkage during the storage period is regarded as one of the main design loads for long span preflexed beams. Rigorous and approximate solutions for the prestress loss are proposed and the creep coefficient and the shrinkage strain are assessed based on test results of a model specimen. The cracking load and the post cracking behavior of the specimen are accurately estimated using the assessed values in the proposed formula. Furthermore, the cracking load is predicted to decrease by about 15 percent when the storage period is increased from two weeks to two months.