Author(s)

BEATRICE BERARDINUCCI, SIMONA DI NINO, AMEDEO GREGORI & MASSIMO FRAGIACOMO

Abstract

Timber–concrete composite structures are often used as floor solutions in new and existing buildings to combine better acoustic separation and improved thermal insulation with increased stiffness and greater load-carrying capacity. The choice of a structurally effective yet cheap shear connection between the concrete topping and the timber joist is crucial to make the composite floor a viable solution that can compete with reinforced concrete and steel structures. The use of inclined screws is a possible option to maximize the slip modulus of the connection and, at the same time, keep the construction cost within acceptable values. In this paper, the results from an experimental and numerical investigation carried out on such a type of shear connection are reported. Push-out tests were carried out at the Laboratory of the Department of Civil, Building and Environmental Engineering of the University of L’Aquila. Each specimen consisted of a timber block connected to two concrete slabs by means of two 8 mm diameter screws per side produced by Rotho Blaas. A layer of OSB was interposed to reproduce the timber flooring often used as permanent formwork for the placement of the concrete slab in new floors or the existing timber flooring when strengthening existing timber structures. Two different screw lengths and interlayer thicknesses were investigated. For each configuration, 10 push-out specimens were tested. The results were statistically assessed by computing the mean slip moduli and the characteristic values of the shear strength. Numerical simulations were also carried out to investigate the dependency of the slip modulus upon the screw inclination and the interlayer flooring thickness.

Keywords

connections, inclined screws, mechanical model, parametric analysis, Timber–concrete composite beams