Punching shear resistance of strengthened reinforced concrete interior slab–column connections using ultra-high-performance strain-hardening cementitious composite material

Abstract

The main target of this article is to find out the most applicable strengthening technique to change the brittle punching shear failure of slab–column connection to a ductile one. The considered strengthening technique uses the combined effect of the internal single-leg stirrups and a thin layer of ultra-high-performance strain hardening cementitious composite material provided in either tension or compression side. Thus, 12 slab specimens divided into four groups were prepared and configured. It was found that the slab provided with properly anchored single-leg stirrups with a cross-shaped thin layer of ultra-high-performance strain hardening cementitious composite material at the compression side proved the most efficient technique among all the considered configurations. This technique enabled the slab to sustain a punching load of about 2.38 times that of the control unstrengthened slab. In addition, it exhibited ductile failure showing strain hardening and softening plateaus. Finally, the experimental shear resistances of all the strengthened slabs were compared against the design resistances stipulated by different design standards such as the ECP 203-2007, ACI 318-14, DIN 1045-1, and EC2-2004 codes. It can be concluded that the failure characteristics stipulated by the DIN 1045-1 code showed the most rational results compared with those of the experimental findings.

Punching Shear Behavior of Slabs Made from Different Types of Concrete Internally Reinforced with SHCC-Filled Steel Tubes

“…Afefy et al [34] studied the punching shear behavior of RC slabs strengthened with UHPFC and found that by adding a thin layer of UHPFC on the tensile side, the bending performance of the slab was improved as it showed better crack distribution in the tensile side. However, the punching load slightly increased by about 5%.…”

Numerical investigation of non-shear-reinforced UHPC hybrid flat slabs subject to punching shear

“…The mechanical properties of different classes of UHPC materials have been extensively investigated [13]. UHPC has been used in several applications such cast in place grout material in bridge connections [14,15], bridge decks [16], thin slabs [17] and strengthening of existing structures [18][19][20][21]. Meanwhile, limited studies have been conducted on the punching shear behaviour of flat slabs made entirely from UHPC [17,[22][23][24][25][26][27][28].…”

Finite element analysis of interior slab‐column connections strengthened by steel angle plates

“…[13][14][15] Next is through strengthening the flexural reinforcement leading to an increase of the effective depth of slab, by bonding fiber-reinforced polymer sheeting or casting an upper reinforced concrete layer. [16][17][18][19][20] The third concept is postinstalled shear reinforcement which was first reported by El-Salakawy et al 21 by inserting vertical shear bolts around the column. This method was then studied further by Wörle, 22 Fernández Ruiz et al, 23 and Adetifa and Polak.…”