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Title: Effect of the Shear Reinforcement Anchorage and Detailing on the Punching Resistance of Flat Slabs

Author(s): Guilherme S. Melo, Mauricio P. Ferreira, Henrique J. Lima, Manoel M. Pereira-Filho, Victor H. Oliveira, Joao P. Siqueira, and Rodolfo Palhares

Publication: Symposium Paper

Volume: 357


Appears on pages(s): 1-18

Keywords: Closed stirrups, Experimental analysis, Flat slabs, Punching shear results, Prefabricated truss bars, Shear reinforcement, Shear reinforcement anchorage, Stud rail.

DOI: 10.14359/51738755

Date: 4/1/2023

Flat slabs with shear reinforcement not properly detailed and anchored as stated by ACI have been used in practice due to simplicity and the gained construction speed. This paper presents the results of 12 tests on slab-column connections with closed stirrups with anchorage variation and prefabricated truss bars as punching shear reinforcement. The behavior of the slabs, in terms of cracking pattern, displacements, and shear reinforcement strains, were analyzed, and ultimate loads were compared with estimations by ACI 318-19. Comparisons with the reference slabs without shear reinforcement showed that these two types of shear reinforcement effectively increased the load-carrying capacity of the tested slabs. For tests on slabs with closed stirrups, it was observed that if ACI detailing rules are followed, improvements in response and ductility of the slab-column connections should be expected. In the case of the slabs with prefabricated truss bars, it was observed that they were able to reach levels of punching shear resistance close to those of a reference slab with well-anchored stud rails. In both cases, further experimental research is needed. ACI 318-19 presented safe strength predictions for the different types of shear reinforcement tested, and in the case of the prefabricated truss bars, this was due to the conservative limitations imposed for calculating the crushing strength of the concrete strut close to the column.