Parametric Study of R.C.C Voided and Solid Flat Plate Slab using SAP 2000

Abstract

The use of flat plate slab is gaining much popularity amongst architects, because the flat plate slab system provides a way for the architect to achieve the concept of high and completely flat ceiling with no beam. As we know that, slab is one of the largest members consuming concrete, when the load acting on the slab is large or clear span between columns is more, the slab thickness is on increasing. It leads to consume more material such as concrete and steel, due to that self-weight of slab is increase. To avoid these disadvantages various studies carried out and researchers suggest voided flat plate slab system to reduce the self-weight of the slab. In this paper various parameters of the voided and solid flat plate slabs is calculated to compare the both systems. To evaluate the performance of the R.C.C voided and solid flat plate slabs, modelling of slabs is carried out using SAP 2000 having span ranging from 6x6 m to 14x14 m of 4x4 bay in both direction with thickness of the slabs 280 to 600 mm. The results drawn from the SAP 2000 are Reaction, Deflection, Moment and Reinforcement required for the voided and solid flat plate slabs. I. Introduction The flat plate floor systems are commonly used in multi-storey buildings, because flat plate floor system present advantages from technical and functional point of view. The self-weight of slab can reduce by replacing the middle height of the cross section of slab with void former. Here, to carry out the parametric study of voided flat plate slabs, different size of hollow void former( 180 to 450 mm ) is consider for various cases of slab thickness ( 280 to 600 mm). The modelling of voided flat plate slabs is carry out same as traditional flat plate slabs by applying the stiffness multiplication factor and modified self-weight of the voided flat plate slabs. The stiffness multiplication factor can be derived from the calculation of second moment of inertia of voided slab and solid slab.The other necessary checks are also done to prove that the voided slab can de model as solid flat slabs with necessary adjustment in certain parameters. The SAP 2000 results show that the behaviour of the voided flat plate slabs is almost same as that of solid voided flat slab in same condition. II. Reaction The main purpose of to carry out results for reaction is to confirm that the methodology that was adopted to perform the study of voided and solid flat slab is acceptable or not. It means that applied stiffness multiplication factor and modified self-weight of the voided slabs are correct or not. To perform the study, for different cases of voided and solid flat slabs are model in SAP 2000 ranging from 6x6 m to 14x14m having thickness 280 mm to 600 mm with spherical ball diameter 180 mm to 450mm respectively and slabs having 4 bays in both direction. For the punching shear criteria, the portion around the column is designed as the solid flat slabs without hollow void former. The results are taken at the centre of the slab considering only gravitational load.To validate the results of Reaction taken from SAP 2000 for voided flat slab, the numerical calculation is carry out of voided slab and the results are shown in Table -1. The Comparative results of reaction for voided and solid Flat slabs are shown in Table -2. The results have revealed that reaction of solid flat slab is higher than that of voided flat slab because of higher self-weight. Moreover, the values of reaction taken from SAP 2000 and by numerical calculation of interior bay are same for voided flat slab. From results it may be conclude that the methodology, which adopted to get the results are acceptable. Table -1 Result for validation of Reaction Slab Thk (mm) Ball Diameter (mm) Span (m) Reaction (KN)