Study of the Behaviour of Moment - Resisting Connection of Softwood Timber Elements

Timber moment - resisting connections present opportunities for streamlined architectural design using timber portal frames with rigid knee junctions, enabling open floor plans by eliminating the need for additional bracing or interior columns. This flexibility empowers architects to craft more versatile floor layouts, enhancing spatial aesthetics and functionality. However, moment - resisting connections between timber members, especially crossing ones, present several challenges – complex design, demanding meticulous detailing and precise fabrication and also lack of a detail design format in codes. One of the biggest disadvantages of timber moment - resisting connections made by steel dowels is development of relative rotation due to the timber as well as dowel’s elastic - plastic behaviour, i.e., such connection may be referred to a semi - rigid group. The main objective of this study is to conduct a detailed investigation of semi - rigid timber connections by performing experimental tests of L - shape models, including examination of timber strength and stiffness properties. The rotational displacement between joined members was determined using measured distances between surface points by Particle Image Velocimetry (PIV). The experimental results are compared with an equivalent linear calculation model. Different connection models are treated by Dlubal RFEM software tools using experimentally obtained embedment stiffness variables. It is found that the linear behavior of the semi - rigid connection is up to approximately 40% of the connection's design capacity, after which distinctly nonlinear force - deformation relationship develops.