Deflection of Cracked RC Beams under Sustained Loading

Abstract

An analytical model that incorporates time-dependent effects (creep and shrinkage) was developed to predict the long-term deflection of cracked reinforced concrete beams under sustained loading. The deflection model includes both bending and shear effects. Correspondingly, experimental studies were conducted to verify the analytical model. Eight specimens were precracked with a diagonal crack width of 0.2–0.3 mm and tested under sustained loading for three months. It was found that the contribution of shear effect to long-term deflection is significant. The predicted deflections including both bending and shear deformations agree very well with experimental measurements. In addition, formulas for calculating creep coefficients from strain increments were derived that provide an approach to calibrating the code specifications. The effects of different creep coefficients on the prediction of time-dependent deformations were discussed.