Time-Dependent Cracking and Crack Control in Reinforced Concrete Structures

Abstract

The paper reviews an investigation of cracking under sustained service loads for reinforced concrete flexural elements and restrained direct tension members. Reliable design models using the tension chord model are presented and are shown to be suitable for predicting the time varying width and spacing of cracks caused by bending and/or shrinkage. Also reported are crack widths and crack spacings from laboratory tests on 12 beams and slabs subjected to sustained loads for periods up to 400 days in order to quantify the effects of steel area, steel stress, bar diameter, bar spacing, concrete cover and concrete shrinkage. In addition, crack widths and spacings induced by shrinkage in eight restrained direct tension members are reported.Predictions made using the analytical design models are compared to the experimental observations and agreement is satisfactory.