A New Formula to Calculate Crack Spacing for Concrete Plates

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Title: A New Formula to Calculate Crack Spacing for Concrete Plates

Author(s): E. Rizk and H. Marzouk

Publication: Structural Journal

Volume: 107

Issue: 1

Appears on pages(s): 43-52

Keywords: bond stress; crack spacing; plate; transverse reinforcement.

Date: 1/1/2010

Abstract:
Different codes have different formulas to calculate crack spacing and crack width developed in flexural members. Most of these formulas are based on the analysis of results of tested beams or one-way slabs. Crack control equations for beams underestimate the crack width developed in plates and two-way slabs. It seems that little attention has been paid in determining the crack spacing and width in reinforced concrete plates. The behavior of reinforced concrete plates and two-way slabs is different from beams or oneway slabs; therefore, the methods developed for beams cannot be directly applied to plates and two-way slabs. In this paper, a new analytical equation is proposed for calculating the crack spacing for plates and two-way slabs. A special focus will be given to thick concrete plates used for offshore and nuclear containment structures. The proposed equation takes into account the effect of steel reinforcement in the transverse direction through the splitting bond stress. The new equation provides good estimates for crack spacing in plates and two-way slabs with different concrete covers. Eight full-scale two-way slabs were designed and tested to examine the effects of concrete cover and bar spacing of normal- and highstrength concrete on crack spacing. The different code expressions are evaluated with respect to the experimental results.