Shrinkage behavior of steel-concrete composite beams

Shrinkage of the slab in composite steel-concrete tee-beams may have a detrimental effect on the behavior of the beam with respect to the service-load limit state. For example, unloaded beams may develop substantial curvatures, and cracking of the concrete slab may take place in the time domain. These effects are both geometric and time dependent. The paper presents a method of determining the shrinkage behavior of isolated composite ree-beams, using the Age Adjusted Effective Modulus Method and making recourse to both a lack of fit approach and to a relaxation procedure. Both of these procedures are found to yield the same result. The theory is validated against tests, and used to investigate the effects of various parameters on the shrinkage-induced behavior of composite beams, so that general conclusions may be drawn. The theoretical model may be programmed very easily on a computer of modest capacity.