PSI - Issue 37

Gonzalo Moltini et al. / Procedia Structural Integrity 37 (2022) 417–424 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

418 2

Nomenclature h c

Height of the connector Base of the dovetail width

b 1 b 2 h l

Distance from the edge of the connector to the dovetail

Board layer thickness Angle of the dovetail

α s

Separation of the connectors (center to center) Span of the panel for the bending numerical model

l

L E i

Length of the panel

Longitudinal modulus of elasticity of the timber in bending Longitudinal modulus of elasticity in tension Longitudinal modulus of elasticity in compression Modulus of elasticity perpendicular to the grain for directions R and T

E t,0 E c,0 E 90 G 0,m

Shear modulus for planes LT and LR

Gr

Rolling shear modulus

ν

Poisson coefficient (considering the same value for every plane)

1. Introduction Timber construction is increasing worldwide, especially due to the government policies focused on the improvement of the sustainability in the construction industry (Milestone and Kremer 2019). The three most common timber structural systems (light wood-frame, post and beam and mass timber) depend both on the wood products and on the associated industry. So, light wood-frame uses small members of sawn timber connected thought steel nails or screws. The post and beam and mass timber systems use mainly glued laminated products, such as glued laminated timber (glulam) and cross-laminated timber (CLT), connected by steel fasteners, bolts and screws. Currently, mid- and high- rise timber buildings uses CLT panels as floors and walls (Muszynski et al. 2017). Since the CLT panels are not a commodity but are manufactured on demand and according to the structural/architectonical design of the building, their production is made by large scale industries. In addition, CLT panels use a high volume of wood to comply with the minimal structural requirements on a building. Therefore, there is a need for a high volume of wood to be available locally (Baño et al. 2018). The need for the inclusion of small-scale industries on the sustainable construction market lead to look for new structural timber products free of adhesives and with a lower consumption of energy on their manufacturing, such as Brettstapel panels (Natterer 2004) or nailed laminated timber (Tannert et al. 2003). With these objectives and with the aim to reduce the wood volume used in CLT panels, adhesive-free Timber to Timber Panels (TTP) were developed by Baño and Moltini (Baño and Moltini 2021) for the use in floors (Fig. 2). The manufacture of the panels was carried out by using local wood ( Pinus sylvestris ) connected by carpentry joints, which had been made using a Computer Numerical Control (CNC) and a moulder machine, both commonly used in carpentry. In the previous work, a numerical model was validated from experimental data. The results showed that the separation of the connectors affects the stiffness of the panels, the shear deformation of the connectors play a vital role in the overall deformation of the TTPs, and the failure is produced by rolling shear in the connectors. Since the serviceability limit state defined the structural design of the TTPs, their structural yield could be improved by enhancing the stiffness. Therefore, the objective of this work is to study the influence of different connector dimensions in the structural behaviour of the TTPs in order to improve their stiffness.