Simple Design Aid for Predicting Shrinkage and Creep Strains in Buildings and Bridges
P. Arumugasaamy and R. N. Swamy
Appears on pages(s):
bridges (structures); buildings; charts; columns (supports); creep properties; lightweight concretes; modulus of elasticity; reinforced concrete; shrinkage; strains; structural design; Design
Presents a simple design aid for predicting long-term (up to 50 years) movements in reinforced concrete columns and bridge beams made of normal and lightweight aggregate concrete. The method is based on the principle of superposition using a creep factor chart, which takes into account varying sizes of members, age at loading, exposure conditions, and the percentage of reinforcement, and it requires only a knowledge of the concrete strength and the loading history of the member. The method is developed from the study of in situ movements in two reinforced concrete structures subjected to increment loading. The shrinkage strains in columns are predicted using a shrinkage chart, which requires only a knowledge of elastic modulus of concrete at 28 days. The predicted load-induced and basic strains show excellent agreement with measured strains in the two structures, and the method shows good agreement with literature. The paper demonstrates how the simple method of predicting long-term movements in buildings and bridges can be utilized by the structural engineer as a designer's tool.