Short-term and long-term deflection of reinforced hollow core concrete slab systems

Abstract

This paper presents a study on different methods of analysis that are currently used by design codes to predict the short-term and long-term deflection of reinforced concrete slab systems and compares the predicted deflections with measured deflections. The experimental work to measure deflections involved the testing of full-scale slabs joined together and, with toppings of different strengths, as simple supported panels. A model based on stress redistribution in concrete in tension and tensile steel reinforcement, due to cracking, was proposed and its predictions were also compared with measured deflections. For the prediction of the long-term deflection, a measured ratio of long-term deflection to short-term deflection was compared with the ACI long-term factor.

Keywords: short term deflection, long-term deflection, concrete, cracking

Botswana Journal of Technology Vo 14(1) 2005: 51-62