Supplementary span-to-depth ratio expressions for one-way slab complying with ACI-318 and SBC-304 deflection limits

Abstract

ACI-318 provides two levels for incremental deflection control depending on the damage by large deflections of the nonstructural elements supported to one-way slabs. For these slabs, the provided deflection limit is relatively low and taken as span/480. Otherwise, the ACI-318 code provides span-to-depth ratio limitations as an alternative approach for deflection control. For the case of damage control by large deflection of nonstructural elements, the ACI-318 code does not provide limitations for the minimum slab thickness. The deflection for these slabs should be checked against ACI limits. For conceptual design, designers prefer to use the tabulated minimum thickness for slabs not supporting nonstructural elements and consequently they must check for deflection. Design limitations for the minimum thickness of such slab are essential to facilitate the conceptual prediction of the slab thickness with safely expected deflection. This paper aims to establish span-to-depth ratio expressions for one-way slabs not provided by ACI-318. A parametric study is performed on one-way slabs supporting non-structural elements to study the effect of design variables on the calculated thickness. The deflection limit considered in this study is (L/480). New expressions for span-to-depth ratio incorporating design variables were developed based on the outcomes of the parametric study and ACI-318 Code deflection limits. The results obtained with the proposed expressions have been verified with the deflection limits given by the code. The predicted deflection values are below the code limits in all considered cases.