ABSTRACT
In search for a solution of a sustainable construction with less impact on environment while maintaining a sufficient structural performance, CLT-concrete composite slabs/beams have been increasingly proposed for medium-to-large span structures. Different types of mechanical shear connectors have been studied in the literature for these composite elements. Among them, the notch type is the most preferable due to the high shear resistance contributed by the concrete. However, steel screw or bolt is needed in the connector to limit the uplift between the timber and the concrete. In this paper, a novel type of notched connectors with a particular shape that is able to limit the uplift without the need for steel bolts is proposed. The main objective of this paper is to determine the local and global behaviours of this new shear connector by experimental investigations. Two series of experimental tests were ordered by Thierry Soquet, an architect of Architecture Plurielle and an inventor of innovative construction systems directed by Horizon Bois. A series of three symmetrical push-out tests were performed on large-scale specimens in order to determine the shear resistance, the stiffness, the deformation capacity and the failure mode of the connector. The test results have shown high shear resistance and large stiffness of the connectors. However, the ductility of the connectors is still limited, as the failure mode was governed by the shear failure of the transverse layer of the CLT. In addition, the global behaviour of the CLT-concrete slab was assessed by a series of two full-scaled flexural tests on the slab specimens under a positive bending moment. It was shown in the test results that the design of the composite slab was not limited by the flexural bearing capacity as a high value of the maximum bending moment was obtained in the tests, but governed by the deflection of the composite slab. The delay in the tests caused by the Covid crisis has moreover set in evidence the importance of the shrinkage of concrete in the total deflection. © Fédération Internationale du Béton (fib) – International Federation for Structural Concrete.