ABSTRACT
The problem of cracking in concrete due to shrinkage and creep is a common one in reinforced concrete construction, especially in floor structures of long spans and / or under strong lateral restraints. The Code of Practice for Structural Use of Concrete 2004 of Hong Kong (hereafter referred to as “the Code”) has provisions to account for the effects. Formulation of the one-dimensional problem based on floor structures simulated as hinged bar members under restraints has been carried out by Liu et al. (2006). This paper adopts similar principle and derives an approach to calculate stress in single storey single bay floor structures in accordance with the Code that can be simply worked by hand calculations or simple spreadsheets. Design charts for general use have also been prepared. Furthermore, the authors have also extended the approach to multi-storey and multi-bay structures. Rapid decrease of stresses in the upper storeys in normal multi-storey buildings has been identified and discussed.
Keywords: Concrete, Creep, Creep coefficient, Effective thickness, Shrinkage, Time steps.
