Punching shear in reinforced concrete flat slabs with hole adjacent to the column and moment transfer

Abstract

The structural behavior and the ultimate punching shear resistance of internal reinforced concrete flat slab-column connections, with one hole adjacent to the column, with or without flexural moment transfer of the slab to the column was investigated. Main variables were: the existence whether or not hole, flexural reinforcement layout and ratio, the direction and sense of the moment transferred and the eccentricity of the load (M (moment transferred to column) / V (shear)) ratio at the connection - 0,50 m or 0,25 m. Seven internal slab-column joining were tested and ultimate loads, cracking, deflections, concrete and reinforcement strains were analyzed. The existence of hole adjacent to the smaller column dimension, the hole dimension, flexural reinforcement rate and placing, the variation of relation Mu/Vu in function of the load, and, than, of eccentricity of the load, influenced the slabs behavior and rupture load. Test results were compared with the estimations from CEB-FIP/MC1990 [7], EC2/2004 [12], ACI-318:2011 [1] and NBR 6118:2007 [5]. ACI [1] and EC2 [12] presented most conservative estimates, although have presented some non conservative estimates. Brazilian NBR [5], even though being partly based in EC2 [12], presented smaller conservative estimates and more non conservative estimates. A modification on all codes is proposed for taking in account the moment caused by the eccentricity at the critical perimeter for slabs with holes.

Non-linear finite element analysis of reinforced concrete flat plates with opening adjacent to column under eccentric punching loads

“…For example, specimens GIII-L1-0.5C and GIII-L1-C have greater capacity than specimen GIII-L1-0, and specimens GII-L1-0.5C and GII-L1-C have similar capacities to GII-L1-0. These results are in agreement with the experimental results performed by Oliveira et al [11]. This can be explained with the crack pattern and principal plastic strain discussed above.…”

“…Over the past hundred years only a moderate amount of research has been conducted on punching shear strength of flat reinforced concrete slabs with openings near columns, in comparison with other subject matters in structural engineering. This is reflected in the design manuals (e.g., building code requirements for structural concrete, ACI-318) that cover these structural systems using predictions that have been widely recognized as conservative in nature compared with experimental results [4][5][6]11,16].…”

Empirical Punching Shear Capacity Equation for Reinforced Concrete Two-way Slabs with Openings

“…It was stated that for small openings, the estimations of codes seem adequate. Oliveira et al [31] experimentally investigated the punching shear resistance of seven internal reinforced concrete flat slab-column connections, with one hole adjacent to the column, with or without flexural moment transfer of the slab to the column. Test results were compared with the estimations from several code approaches.…”

A Parametric Study on Lateral Load Behavior of Interior Flat Plate - Column Connections

“…However, providing a shear reinforcement is not always easy and thus this paper is limited to plates without transverse reinforcement. Other variables considered in these types of tests were the supporting column rectangularity [15]- [17] and arrangement and size of service openings on the plate surface [18]- [21].…”