Punching shear analysis of reinforced high-strength concrete slabs

Abstract

An experimental investigation was conducted at the structural laboratory at Memorial University of Newfoundland to examine the behaviour of high-strength concrete two-way slabs. It was evident that a new mechanical model is required to predict the punching shear capacity of such slabs. The experimental results of the tested slabs with regard to deformations, strains, ultimate capacity, and modes of failure were examined. Based on the test results, a mechanical model was adopted and developed for high-strength concrete slab applications. The formulation takes into account the actual behaviour of the high-strength concrete and steel. The proposed model gives a fairly good agreement between the predicted and experimental punching loads.A la suite d'une etude expCrimentale rCalisCe au laboratoire des structures du Memorial University of Newfoundland afin d'examiner le comportement de dalles de bCton h deux voies h haute rksistance, les chercheurs ont constatt la nCcessitC d'un nouveau modkle mkcanique afin de prCdire la contrainte de poin~onnement de ces dalles. Les rksultats experimentaux des essais relatifs h la dCformation, h I'effort, h la capacitC ultime et aux modes de dtfaillance ont CtC examinCs. Compte tenu de ces resultats, un modkle mCcanique a CtC adopt6 et ClaborC pour les dalles de bCton h haute resistance. La formule tient compte du comportement actuel du bCton h haute rCsistance et de l'acier. Le modkle proposC permet d'obtenir une assez bonne concordance entre les charges de poin~onnement prCvues et celles mesurCes en laboratoire.Mors clPs : flkches, dkformations, mCcanismes de dkfaillance, plaques de bCton plates, bCton h haute rCsistance, charges (forces), modkle mtcanique, contrainte de poin~onnement, bCton armC.[Traduit par la rCdaction]Can. 1. Civ. Eng. 18, 954-963 (1991) IntroductionSummary of experimental investigation Research on punching shear has yielded a number of methods by which the ultimate shearing strength of slabs can be predicted. In general, the various suggested approaches can be described as either the results of an empirical study, in which a statistical analysis of the available test results is used to establish a relationship between the load or stress at failure and the parameters of the slab, or the result of a rational study, in which the strength of the slab materials and the mechanism of failure are idealized and described mathematically.The ACI 318 (American Concrete Institute 1989) and CSA (CAN3-A23.3-M84) (Canadian Standards Association 1984) codes are based mainly on Moe's work (1961), while the BS 81 10 (British Standard Institution 1985) code is based on Regan's work (1974). These present building code specifications for the shear strength of reinforced concrete slabs are based on the test results of slabs made with relatively low compressive strengths, varying mostly from 14 to 40 MPa. Test results revealed that the present North American codes overestimate the influence of the concrete strength, as a factor, on the ultimate capacity of two-way slabs. Hence, it is...

Punching shear strength of RC flat slabs at interior connections to columns

“…The method is applicable to the assessment of the punching shear strength of flat slabs connected to interior columns with circular or rectangular cross-sections without shear reinforcement. The method proposed was validated with 209 tests on isolated specimens reported in the literature (suspended slabs and footings) (Al-Yousif and Regan, 2003;Bazant and Cao, 1987;Bernaert and Puech, 1966;Beutel, 2002;Birkle and Digler, 2008;Bompa and Oneţ, 2011;Broms, 1990;Caldentey et al, 2013;Elstner and Hognestad, 1956;Ghannoum, 1998;Guandalini et al, 2009;Gosav et al, 2013;Guidotti, 2010;Hallgren, 1996;Hegger et al, 2009;Heinzmann et al, 2012;Inacio et al, 2013;Kevin, 2000;Kinnunen and Nylander, 1960;Krueger, 1999;Ladner, 1998;Ladner et al, 1977;Marzouk and Hussein, 1991;McHarg, 1997;Menetrey, 2002;Moe, 1961;Mongi, 1990;Moreno, 2013;Muttoni, 2008;Muttoni and Fernandez Ruiz, 2012;Oliveira et al, 2004;Pralong, 1982;Ramadane, 1996;Regan, 1986;Rizk et al, 2011;Sagaseta et al, 2011;Schaefers, 1984;Swamy and Ali, 1982;Tomaszewicz, 1993;Urba...…”

“…Variation of the reinforcement ratio from low to high (0·54% to 2·10% and 0·94% to 1·49% respectively) reveals excellent agreement between the predicted and reported Equation 14 Equation 13 Equation 14 Equation 13 Equation 13 Equation 13 Equation 13 Equation 14 Equation 14 Equation 13 The influence of the slenderness of the slab is best captured by Equation 13 (Figure 9(d)), which closely predicts the ultimate punching strength from the tests reported by Tomaszewicz (1993). The size effect is emphasised by means of the fractal parameter of concrete (l ch ) and effective depth (d) from tests carried out by Marzouk and Hussein (1991) and Rizk et al, (2011) (Figure 9(e)). Although all the results show a similar trend of the normalised strength in relation to d/l ch , the actual behaviour is better anticipated by the proposed method (Equations 13 and 14) and Eurocode 2 for small fractal values (l ch ).…”

Finite Element Analysis of Concrete Bridge Slabs Reinforced with Fiber Reinforced Polymer Bars

“…Other codes and design provisions (BS8110 1997) assume that the punching shear is proportional to the cubic root of concrete compressive strength rather than the square root. In addition, these code equations are based on the test results of slabs made with relatively low compressive strength, varying mostly from 14 to 40 MPa (Marzouk and Hussien 1991). To investigate the effect of concrete compressive strength on the behavior of GFRP-RC deck slabs, different concrete compressive strengths were investigated.…”

Behavior of Concrete Bridge Decks Reinforced with MMFX Steel

“…The strain profile indicates that the top surface of the concrete at the vicinity of the punching area exceeded the limiting compressive strain value. The limiting compressive strain at a distance y from the edge of the loading plate reported by Kinnunen and Nylander (1960) was 0.0019, Marzouk and Hussein (1991) was 0.00215, and Mufti and Newhook (1998) was 0,002, where y is the distance from the bottom surface of the slab to the root of the shear crack at failure. The strain profile obtained from the PI gages at the edge of the right span (T8 and B12 in Figure 4) is shown in Figure 17.…”