Abstract This work primarily aimed to compare the bubble slabs experimentally with solid slabs under the influence of limited repeated four-point loads. Therefore six slab strips were manufactured in the… Click to show full abstract
Abstract This work primarily aimed to compare the bubble slabs experimentally with solid slabs under the influence of limited repeated four-point loads. Therefore six slab strips were manufactured in the same forms, except the cross-section type. Three were solid, and the others were voided due to placing 70 mm-diameter balls inside them. In addition, the shear span to effective depth ratio (a/d) was also studied. Accordingly, one slab from each type was tested, with the a/d being either 2, 3.5, or 5. The applied loads were repeated ten cycles at a load level of 25 kN, representing 70 % of the ultimate load estimated according to the ACI-19 code, and then lasted gradually until the slabs' collapse. The results recorded that the balls' presence made slabs failed abruptly due to shear mode regardless of the a/d. For the same slab type, the slabs' strength, stiffness, and toughness reduced as the a/d was increased; nevertheless, the ductility showed an opposite trend. Compared to solid similars, the bubble slabs' mechanical measurements, excluding the service stiffness, dropped notably. However, the stiffness decay was small, below 15 %. Moreover, sustainability analysis was performed, and the voided slabs were found to be more eco-friendly than solid ones due to reductions in the CO2 emission and consumed embodied energy, about 14 % and 10 % below those of the solid slabs.
               
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