Behaviour of Reinforced Concrete Stiffened Skew Slab

Abstract

The skew slabs have various applications as a floor of bridges and buildings. This is pertinent when it is not possible to cross the river or gap at an angle of 900. The skew slab behaves differently in comparison to the normal slabs because of various factors, i.e. skew angle, aspect ratio, boundary conditions and placement of reinforcement. Also, it becomes extremely complicated when sometimes beams are provided along its unsupported edges to meet the serviceability criterion prescribed in the applicable design codes. Any change in the physical parameters of these factors causes a considerable change in the moment-field induced in the slab under given loading conditions. The available design guidelines/codes give a set of design moment coefficients for a particular set of the skew angles and the slab aspect ratio only; these are based on the empirical formulae and the related performance studies conducted on such slabs in the past. Design aids and plans suggested by Indian codes are applicable for standard skew angles, i.e. 150, 300, 450 etc. with selective spans only. However, in actual practices, numbers of cases are encountered wherein the skew angle and aspect ratio of the slab panel does not fit into recommended guidelines. This happens either due to the very high land cost and space limitations. In the present thesis, an attempt is being made to develop an improved theoretical formulation to predict the ultimate flexural capacity of laterally loaded reinforced concrete (RC) skew slabs. In the first phase of the study, an analytical model has been suggested for the analysis and design of laterally loaded skew slabs for different cases: 1) Single panel RC skew slabs simply supported from two opposite edges (straight and skew). 2) RC skew slab stiffened with internal inbuilt beams cast monolithically along the span resting over simple supports along the span at the centre and its outer boundaries. The experimental programme was also designed to validate the suggested analytical models and equations.