Comparative Study on Slab Deflections

Abstract

Slabs are one of the most common structural components in RC-framed structures, usually analysed under transverse loading. In the analysis, the thickness of the slab generally governs the serviceability requirement for deflection. The thickness of the slab controls the weight of the building since its contribution is nearly 50% of the total weight of the building. In order to minimize the weight of the building, proper analysis of the slab ensures minimum thickness satisfying deflection criteria. For a given loading, span, and assumed thickness of the slab, analysis will be performed using the material properties such as modulus of elasticity and Poisson’s ratio. Several theories, including the Rankine-Grashoff theory, Timoshenko’s plate theory, Marcus, and other methods have been proposed over the years using the same concept. These methods do not consider the participation of reinforcement in deflection estimation. IS code 456 – 2016 specifies limiting span to depth ratios with suitable modification factors based on percentage of tension reinforcement and stress level in steel for satisfactory serviceability criteria of deflection. In the present study, an attempt was made to compare the slab deflections analytically and experimentally with and without reinforcement contribution for the exactness of proposed theories. It concludes that, in one-way simply supported slabs, theoretical values differ by 45% from experimental values in reinforced concrete (RC) slabs. In two-way simply supported plain concrete (PC) slabs, the Rankine-Grashoff theory is in good agreement with the experimental values. Theoretical values of the two-way slabs when compared with experimental (RC slab) values are in good agreement with plate theory.

Computer Programming for Analysis and Design of Edge Supported Rectangular Two-Way Solid Slab by Es En 1992-1-1:2015

“…Software comprises the electronic instructions that govern the computer's functions. A program consists of sequences of instructions to a computer, where it is written to perform specified task on a computer [7,15]. Unlike a program where a program is developed by individuals for their own personal use, software is much more complex.…”

“…Supported ES EN 1992-1-1:2015: For Mild exposure = 20 mm, For Moderate exposure = 30 mm, Effective depth = depth of slab -clear cover -1/2 diameter of bar, The Effective span of the slab shall be lesser than the 2, L = clear span + d (effective depth). L = Centre to center distance between the support [22,14,15,21]; 4. Calculate the factored loads and Determine moment coefficients; 5.…”

“…It is meant for multiple users and therefore has a good interface, designed systematically, thoroughly tested and implemented carefully. Software is most often very complex and too large for one person to create and develop single handedly [8,15]. For example, given software that records names and addresses in a database.…”