# Parametric Study of Three Types of Timber Connections with Metal Fasteners Using Eurocode 5
## 1 Introduction
Metal connector plates are a particular case of dowel type fasteners as they combine the side loading actions of dowel fasteners and the strength properties of metal plates [1; 11]. Bearing type fasteners, such as split ring connectors and shear plates transmit only lateral loads through the bearing on the connected materials. Hanger type connections are a combination of dowel and bearing type fasteners. These connections normally support a structural member and are connected to another member by a combination of dowel and bearing action [1; 11]. [PERSON] [12] presented an experimental investigation to study the load carrying capacity, stiffness, load-slip, failure modes and ductility of aluminum-timber screwed connections. The selection a fastener for a specific design application depends on the type of connection and the strength required. Each connection must be designed to transmit loads effectively and provide acceptable performance for the life of the structure without causing excessive cracking, or deformation of the elements. As [PERSON] [13] mentions, dowel type fasteners are one of the most used types of timber connections. The strength of mechanical fasteners dependents on many factors, such as species density, angle of load to grain, spacing of mechanical fasteners, and edge and end distances [3; 4; 7; 11]. The density of the wood is also important due to the contact with the dowel, namely due to the friction between these parts. Other important parameters are the calculation of the load-carrying capacity and the effect of the stiffness material of the connections. These parameters are crucial to the maintenance and durability of the structure, especially for large spans with many connections and in structures with heavily loaded connections [14]. The aim of this work is to present the analytical formulation that can be applied in the design of timber connections. Several types of connection were studied to verify the interaction between all parameters and characteristics between the involved parts. Despitesome existing research in this area, there are not comparative studies between the different types of connections, which are submitted to the same analysis parameters. Timber connections have been studied due to their impact on building construction, their strength, ductility, and ability to increase structural performance in service [5; 6; 7; 15; 16; 17]. In heavy wood structures, double-shear timber connections with steel fasteners are widely used to assemble structural members and transfer loads [11]. The connections in this study are steel-to-timber and timber-to-timber, called wood-steel-wood (W-S-W), wood-to-wood (W-W-W) and steel-wood-steel (S-W-S) connections, both joined by steel dowels, in double shear. The advantage of the presented study is the comparison between all these connections using the same design variables. It will be possible to identify the mechanical strength and dimensions required versus the number of fasteners to be used in each one. The effect of strength and wood density were also investigated, and these are important variables to consider when designing timber connections. Different procedures will be used for the design process, according to the simplified equations presented in Eurocode 5, part 1-1 [18]. To obtain the designed timber connections with metal fasteners, this work is based on simplified and analytical equations with several parameters. A parametric study is presented, using different applied loads and steel dowel diameters, which allow demonstrating the results of timber connections in double shear and the associated failure mode. According to the procedure, the study can be used to improve the design. As a general conclusion, the calculated number of dowels increases with the applied tensile load. Small dowel diameters have a greater effect on the number of fasteners needed. And the increase in the number of dowels required for the lower strength and density of the wood is evident.