Effect of Construction Type on Structural Behaviour of R.C Bubbled One-Way Slab

Abstract

Using Bubbles in the slab is a revolutionary method of eliminating concrete from the middle of conventional slab as this concrete does not perform any structural function, thereby dramatically reducing structural dead weight. This research presents experimental study to investigate the effect of construction type on the strength and behaviour of bubbled one-way slabs. The experimental program consists of testing four slabs with dimensions of 1850mm×460mm×110 mm. One1of the tested slabs was conventional slab (without bubbles), two bubbled slabs with different types of construction (simple and filigree bubbled slabs) and the remaining one is filigree bubbled slab strengthened with steel cage. The bubbles were made of recycled plastic balls. The experimental results show that the stiffness reduction factor for all the bubbled slabs was (0.87), this leads to decrease the ultimate strength of bubbled slabs and to be smaller than that of the solid slab by 4.4% 69% and 1.7% respectively. Also an increase in deflection at yield load (∆y) by about (10% to 12%), at the same time the crack load is found to be decreased by (13% to 40%). The simple bubbled slab is more efficient when compared with filigree bubbled slab. Also the results show that the use of steel cage in filigree bubbled slab gives an increase in the ultimate load by 69% and an increase in the ultimate deflection by about 77% when compared with filigree bubbled slab without steel cage.

Deflection Analysis of Layered Slabs with Plastic Inserts

“…To reduce the self-weight of the overlay structure, the monolithic layer of the overlay may include hollows. In this case, hollows are suggested to be formed by using plastic inserts [ 3 , 4 ], as shown in Figure 1 . Installing hollows in the overlay slab decreases the consumption of concrete by up to 20–30%.…”

“…1 tonne of cement is known to emit up to 500 kg of CO 2 into the environment [ 5 ], which demonstrates that the rational solutions of reinforced concrete structures significantly reduce energy and raw material costs and environmental pollution. Plastic inserts used for creating slab hollows can be made from household plastic waste, which grants the environmentally friendly management of plastic waste [ 3 , 4 ].…”

“…A number of sources [ 1 , 4 , 7 , 8 , 9 ] provide that at the initial service stage of loads affecting the above introduced structures, both layers work and deform together until loads reach 50% of bearing capacity. Conventional structural analysis applies to the previously mentioned slabs because the slab has the same load-bearing capacity as a monolithic reinforced concrete slab of the solid cross-section [ 3 , 4 , 10 , 11 ]. Structural analysis is possible by using conventional FEA software packages referring to the same design standards applied for the monolithic reinforced concrete slabs of the solid cross-section.…”

“…The stiffness of the bond between two concrete layers must be considered when calculating the slabs at this particular stage of loading. At high shear stress, the rigid bond of the layers may become partially rigid, and therefore slab layers slip relatively to each other [ 4 , 24 ], this occurrence is shown in Figure 2 . Such type of failure mode is described in studies by H. Ji and C. Liu, 2020 [ 25 ], K.M.A.…”

“…A. M. Ibrahim et al, 2019 [ 4 ] and J. Valivonis and G. Marčiukaitis 2007 [ 28 ] researched the layered reinforced concrete slabs and found that it was useful to assess the partial stiffness of the bond between concrete layers. This helps to obtain more accurate results of structural analysis and provides a possibility of assessing structural behaviour at different stages of service evaluating the partial stiffness of the bond.…”