Performance of Notched Coach Screw Connection for Timber-Concrete Composite Floor System

David Yeoh Eng Chuan, Massimo Fragiacomo, Pietro Aldi, Marta Mazzilli, Ulrike Kuhlmann

The notched connection for timber-concrete composite beams is obtained by cutting a notch from the timber beam and filling it with concrete during the pouring of the concrete slab. This type of connection has the advantage of high stiffness and strength compared to mechanical fasteners. The paper presents the outcomes of a parametric study of fourteen variations of notched connections which were loaded to failure under shear in push-out specimens. Laminated veneer lumber (LVL) was used for the timber part. Stiffness and strength values obtained from the different connection variations were compared to each other in order to identify the best types. Rectangular and triangular notches reinforced with a coach screw were found to perform satisfactorily. An alternative connection system with punched metal plates was also found to perform well, with the additional benefit of ease of construction. The experimental results were compared with numerical results carried out using a 3D finite element model implemented in ANSYS software package. Agreement was found between the predicted and the experimental failure mechanisms, however further work is needed to fully calibrate the software on the experimental results.

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