The results of experimental test of nine thickset reinforced concrete slabs in punching are presented in the this paper. The aim of the tests was verifi cation of the Eurocode EC 2 procedure, by which the ultimate shear stresses vRd,c depend on the slenderness of the slab. Besides of the performed tests results, the analysis of the foreign investigation of the fundaments is also included. The test results, as well as other tests, show the correctness of the function assumed in Eurocode 2, which gives correlation between ultimate stresses vRd,c and shear slenderness.
In the paper an alternative method for increasing punching shear resistance of the flat slabs from lightweight aggregate concrete by means of hidden steel fibre reinforced capital was presented. Previous experimental studies demonstrated that the addition of steel fibres to concrete allows for increase in the punching shear resistance of flat slab. Steel fibres modify the tensile strength of concrete, which translates into increased ductility of the material. The results of the experimental investigations were presented, the aim of which was to assess the effectiveness of the proposed solution. For economic and technological reasons, a hidden capital of a height equal to half of the slabs depth was made so that the top reinforcement could be installed later. It was found that presented solution allowed to increase the load carrying capacity by about 36% with respect to the control element, made entirely of lightweight aggregate concrete.
In the paper the results of experimental investigations concerning flat slabs made from reinforced lightweight concrete with sintered fly ash aggregate CERTYD were presented. In the research program 6 models made in a natural scale were included. The main variable parameter was slab longitudinal reinforcement ratio. The aim of investigation was the experimental verification of efficiency of double-headed studs as punching shear reinforcement. In the existing technical approvals such kind of reinforcement was allowed only in normal concrete slabs. It was demonstrated that double-headed studs can be an effective transverse reinforcement of lightweight aggregate concrete slabs. The use of double-headed studs resulted in increase in the ultimate load from 19% to 44%, depending on the slab reinforcement ratio which ranged from 0.5% to 1.2%. The comparative analysis showed that the Eurocode 2 provisions were conservative in relation to the experimental results, which were on average 42% higher than the theoretical ones however with a very low 7% coefficient of variation.