Failure assessment of flat slab-to-column members

Abstract

This paper is concerned with the ultimate behaviour of isolated flat slab members at the connection to interiorcolumns. An experimental programme that focuses on the response of two-way members with various material and geometric configurations is presented. A full account of the results of ten scale tests comprising members with and without transverse reinforcement as double-headed shear studs is given. After describing the experimental arrangement and specimen details, the results and observations obtained from tests are provided and discussed.Particular attention is given to the influence of a number of key parameters that characterise the behaviour at the ultimate state such as slab thickness, layout and amount of the flexural and transverse reinforcement. The test results enable direct assessment of the governing factors that affect the behaviour and failure mode of flat slab members at the connection to interior columns. Finally, experimental results and observations are used to assess the adequacy of strength predictions obtained from analytical models currently adopted in design.

Nonlinear numerical simulation of punching shear behaviour of reinforced concrete flat slabs with shear-heads

“…and b0 situated at 2d from the column face. As observed in Figure 9 and in previous tests [12,42] Figure 14 summarises the ratio between the test or numerical strength and predicted strength (Vnum/test /Vcalc) versus the ratio between the test or numerical result and the flexural strength, from the application of the existing codified guidelines (Equations 7-10) and Equations (1)(2)(3)(4)(5)(6) proposed in this paper. Values of Vnum/test/Vcalc above unity depict conservative predictions, whereas those below unity represent unconservative estimates.…”

“…Brittle failures, which can occur at the slab-column connection, may typically be prevented through drop panels or by reinforcing the critical region with transverse bars (e.g. [1][2][3]) or structural steel inserts [4][5][6][7][8][9][10][11]. The performance of a flat slab with transverse reinforcement is however strongly dependent on the arrangement, type and size as well as bond characteristics of the rebars.…”

“…Moreover, tests on 16 × 120 mm thick model slabs and 4 large-scale 3 m×3 m and 250 mm thick specimens investigated the optimal shear-head configuration and their effect on punching shear capacity [20]. Other intricate shear-head systems exist, including for example composite cruciform systems consisting of vertical steel plates acting as shear-legs to 3 which headed studs are welded for composite action combined with special steel-endplates for strut support [21].…”

Reinforced concrete flat slabs with openings at different distances from the column

“…Due to the different values of compressive concrete strengths (fc) of the models tested, the values of failure loads of slabs with openings were normalized (Vu,norm) as a function of the variable fc, as shown in Table 3. The flexural resistance of the slabs (Vflex) was calculated through the Yield Line Method, according to Gosav et al [16]. The configuration of the yield lines adopted for the slabs was according to the cracking pattern observed during the tests.…”

Nonlinear numerical simulation of punching shear behavior of reinforced concrete flat slabs with shear-heads

“…Brittle failures, which can occur at the slab-column connection, may typically be prevented through drop panels or by reinforcing the critical region with transverse bars [1][2][3] or structural steel inserts [4][5][6][7][8][9][10][11]. The performance of a flat slab with transverse reinforcement is however strongly dependent on the arrangement, type and size as well as bond characteristics of the rebars.…”