Full scale testing of timber-concrete composite floors in an overhanging configuration

Abstract

The behavior of timber-concrete composite floors in an overhanging configuration has been analysed. The floor consisted of a prefabricated T-shape piece formed by a glulam flange glued to a plywood rib and connected to an upper concrete slab poured in situ. The connection between both materials is achieved by penetrating the concrete into the holes made in the rib.Three-point bending tests were performed with a total of 8 specimens with depth of 25, 30 and 35 cm and overhanging length of 1.50, 1.80 and 2.10 m, respectively. That means a length-to-depth ratio equal to 6 in all cases.The experimental results showed that the lowest ultimate load value obtained was 8.03 and 5.55 times higher than the estimated service load for a building with residential use (5 kN/m2) and public use (9 kN/m2), respectively.Two types of failure were observed after a marked cracking process in the concrete as the ultimate load value was approached: tensile failure affecting the plywood rib and shear failure at the glulam flange-plywood rib connection.The maximum deflection for the total load was between 1/358 and 1/523 of the overhanging span for the estimated loads for a residential use building (5 kN/m2), and between 1/266 and 1/390 for public use buildings (9 kN/m2).Regarding to vibrations, floors in an overhanging configuration with a length-to-depth ratio equal to 6 and a simply supported portion equal to four times the length of the overhanging portion, with total loads up to 9.0 kN/m2, both in multi-storey buildings for residential and office use, present a high comfort level.Consequently, the proposed timber-concrete composite (TCC) overhanging floor solution has demonstrated high stiffness and strength that make it a suitable alternative for the construction of high-performance lightweight floors in multi-storey buildings.