Double Shear Steel-To- Timber Connections Design and Investigation of their Load Carrying Capacity According to EC5

The purpose of this study was to predict and evaluate the load carrying capacity of double shear connections of hybrids wood products in combination with steel dowel and plates based on European codes (EC5). The main variables were layered hybrids (4 levels), fastener diameter(2 levels) and fastener number in raw (3 levels). For this study, new types of engineered wood products were used in which plywood and OSB were joined together as three-layer structural components by a single component of polyurethane resin. The fastener was steel dowel 6 and 8 mm in diameter and steel plate 4 mm thick. The values of the load carrying capacity of the connections were predicted based on EC5 equations and Johansen failure modes. The test specimens were loaded according to EN 26891 to investigate the effect of the research parameters. The results showed that the effect of the increasing of plywood share especially in the middle layer of the new hybrids was significant on the increasing of load bearing capacity of the joints. Increasing the diameter of the connector from 6 to 8 mm also increases the load bearing capacity of the joints. Also, as the number of pins in the row increases, the load bearing capacity of the joints is increased. The research findings indicate that the formulas provided by EC5 have the ability to predict the strength and behavior of the joints in this study and even in some treatments the experimental values were higher than the predicted values. POLT1 and POLT2 composites in double shear connections have load bearing capacity values close to EC5 predicted values and also more than it. In studying the failure modes of the connections, steel dowels of 6 mm showed better performance.