Extension of the ζ-method for calculating deflections of two-way slabs based on linear elastic finite element analysis

Abstract

Deflections are among the most complex aspects of reinforced concrete behavior. Furthermore, deflection control is increasingly a governing criterion in design, especially in the case of two-way members such as flat slabs or edgesupported slabs. However, simple and theoretically sound and adequately verified methods for calculating deflections of two-way reinforced concrete members have been lacking. Therefore, in this study, a novel method is proposed for deflection control of two-way slabs. The method is an extension of the ζ-method (as defined by Eurocode 2 and the fib Model Code 2010) of interpolating deflections between the uncracked and fully cracked state. As a basis, the method uses elastic deflections that are obtained through linear elastic analyses in finite element software. The elastic deflection is then adequately transformed based on the properties of a representative section, to account for cracking, shrinkage and creep according to a modified version of the ζ-method. Finally, the method is validated against available experimental results from literature, obtaining satisfactory precision and accuracy. The method proposed in this study aims at providing an easy-to-use tool for designers carrying out deflection control of two-way reinforced concrete slabs.