Modification of Creep-Prediction Equation of Concrete utilizingShort-term Creep Tests

摘要

Creep of concrete is one of the most dominating factors affecting time-dependent deformations ofconcrete structures. Especially, creep deformation in a prestressed concrete reactor structure should bepredicted accurately for the calculation of prestress loss of prestressed concrete structures in design andconstruction. Existing creep-prediction models for concrete contain several drawbacks such as lack ofaccuracy, requirement of long-term for test, and simplified consideration of material components in mixdesign. The creep-prediction equation of CEB-FIP model generally underestimates the creep of concrete dueto simplified consideration of the changes in material components of the mix design. In order to improveits prediction of the creep, a methodology to modify the creep-prediction equation is proposed.In this study, concrete specimens having same compressive strength are manufactured with threedifferent mixture proportions and short-term creep tests are first carried out for the early-age concretespecimens by loading at the ages of 7 days and 28 days covering first 28 days after loading. The testresults obtained with the different mixture designs are analysed and compared with predicted ones. Then,the prediction equation is modified by using the results from the short-term tests. The modified equationare finally verified by comparing predicted results with results obtained from long-term creep test coveringa year after the loadings.