Punching Shear Behavior of Bubbled Reinforced Concrete Slabs

Abstract

This work presents the shear capacities and sustainable analysis of reinforced concrete (RC) two way hollow slabs with plastic sphere voids, also known as bubbled RC slab system. A bubbled RC slab has two-dimensional arrangement of voids included to reduce the self-weight. The strength and behavior of bubbled RC slabs with plastic spheres voids is investigated experimentally. Three RC square slabs of 1000mm x 1000mm dimensions have been tested to obtain the punching shear behavior. Variables of the experimental work are: thickness of reinforced concrete slabs, and volume of concrete. It has been found that bubbled RC slab, (with ratio of bubble diameter B to slab thickness H, B/H= 0.80), has about (92.163 %) of the ultimate load capacity of a similar reference solid slab (which has the same slab thickness). Also, bubbled slabs consume about (74 %) of the concrete needed for the similar solid slab. A small increase in the deflection at 0.7Pu by about (0.718%), at the same time, the cracking load is found to be decreased by about (6.286%) relative to solid slab system. For approximately the same volume of concrete, the bubbled slabs result an increase in the ultimate load capacity of bubbled slab by about (6.4%) and a reduction in the deflection at 0.7Pu by about (1.10%). At the same time, the cracking load is found to be increased by about (10%). Analysis of the amount of input raw materials, energy consumption, and CO2 emissions for the bubbled RC slabs, showed that there is a reduction in the amount of the input raw materials used such as sand, gravel and cement up to 28% and this leads to a reduction in the cost of these materials. Sustainable analysis gives a fact that the energy consumption and CO2 emission can be reduced by about (12 to 21%), so it can be said that, the use of bubbled RC slabs is very useful in terms of sustainable building and has important contribution to construct the environmentally friendly buildings.