Engineering ductile notch connections for composite floors made of laminated timber and high or ultra-high performance fiber reinforced concrete

Abstract

Different kinds of ductile connectors have been lately developed for enhancing the structural ductility of Timber-Concrete Composite (TCC) structures. In particular, ductile notch connections can be designed by favoring the local compression failure of wood fibers. This work aims at further developing economic and ductile notch connector by considering different floor systems made of Glulam Laminated Timber (GLT) beam or Cross Laminated Timber (GLT or CLT) slab connected with a High Performance Concrete (HPC) slab or a Ultra-High Performance Fiber Reinforced Concrete (UHPFRC) slab.Firstly, the geometry of the notch connector was suitably designed for favoring a ductile hierarchy of collapse modes. Then, a wide campaign of push-out tests was carried out to characterize the shear behaviour of 14 connection configurations by varying the notch geometry, the concrete type and the possible presence of acoustic insulation. Finally, based on the experimentally identified connection shear law, an example of design is presented for a TCC slab of 9 m span. The insulation layer was found to reduce the connection stiffness, but to increases the structural stiffness thanks to the enhanced lever arm of the composite action. For plastically designed TCC structures, the connection ductility allows increasing the structural ductility for both GLT-(U)HPC and for CLT-(U)UPC floor systems.