# Parametric Study of Three Types of Timber Connections with Metal Fasteners Using Eurocode 5
## 1 Introduction  
Timber connections have been studied by researchers from several countries, where different analytical and experimental models are developed to solve many questions about this type of elements. These elements are considered the essential parts of a wooden structure due to their ability to connect parts, transmit high loads, and, therefore, require more importance during the project [1, 2]. However, these connections can also be the weakest points in the structure [3, 4]. The connections have the function of transmitting the load-carrying capacity between the parts of the structure and providing continuity between the members. Thus, the strength and durability of these types of structures depend mainly on the dimensioning of the joints between the elements [3, 4]. [PERSON] [3] presented different studies of wood connections subjected to different tensile loads and dowel diameters, allowing for the understanding of the relation between all parameters. [PERSON] [4] studied different wood steel connections in double-shear, and the results showed that the smaller dowel diameters increase the number of fasteners used in the connection. [PERSON] [5] and [PERSON] [6] studied typical wood-steel connections loaded in shear and presented three-dimensional numerical simulations to obtain the maximum load capacity of fastener. [PERSON] [7] presented a work that describes a numerical methodology to study the typical two-dimensional cross-section of a connection subjected to fire to calculate the temperature evolution. [PERSON] [8] experimentally analyzed two types of bolted timber connections under fire to develop simplified calculation methods. The design of wooden connections requires the use of different rules to ensure safety and structural stability. The strength and stiffness of the timber connections are important criteria to consider for the serviceability of a structure. Depending on the application, the connection has different fastener options, using bolts or dowels, and steel plates, which are more prevalent in massive timber structures, since they can carry heavy loads [2; 3; 4]. There are different connections: carpentry joints, glued connections, and mechanical connections. Carpentry joints involve wood joining elements, generally subjected to axial compressive loads, applied in carpentry. These internal compressive forces keep the surfaces in close contact, often without other devices, but with notches in the connected members. Carpenter connections are not included in Eurocode 5, but national regulations may apply [2; 3; 4]. Glued connections are regularly used in wooden constructions to connect new elements and reinforce existing members. There are several types of glued connections, such as structural finger joints and glued steel rods [1; 3]. This type of glued connection follows national design building standards. These connections provide greater strength and better aesthetic appearance compared to the dowel type connections due to the inclusion of steel rods inside the wooden member [9]. [PERSON] [9] presented different experimental results for glass fiber reinforced polymer to timber glued joints. Its experimental method a single lap joint with the aim of selecting the most suitable adhesive for the joints. Mechanical connections are divided into dowel type fasteners and bearing type connections [2; 3; 5; 6; 7]. Dowel type fasteners, such as bolts, screws, and nails, transmit either bearing stresses and axial loads parallel to the axis of the fastener [2]. Dowels are circular rods of wood, steel, or other materials as carbon-reinforced plastics. It is the generic term used for a fastener that transfers load between connected members by a combination of bending and shear in the dowel and shear and bearing (embedment) in the wood [10]. Lateral loads are transmitted by bearing stresses created between the fastener and the connecting members, and the withdrawal loads are axial forces parallel to the axis of the fastener transmitted by friction or bearing to the connected materials [2; 3].