In this article semi rigid joints of timber structures are analysed which are applied in beam to beam connections. The main design principles of semi rigid timber joints’ are discussed. New type of joint construction for glued laminated timber elements’ is proposed and laboratory experimentally tested. Beam to beam joint is installed using welded steel details which are anchored into timber elements. Steel detail's back T shape part is used for anchoring into timber element. Beam to beam joint is symmetric along the longitudinal element's axis; it has two steel details in tension and compression zones which enable this joint to take axial, shear forces and bending moment. To avoid initial free rotation of the joint; filler is used to ensure contact between glued laminated timber element and steel detail. Cement based filler with polymer fibres is used for this purpose. Three joints with the same geometrical and physical parameters are experimentally tested in four point bending; analyzed connection is in the middle of simply supported beam. Purpose of laboratory experiments is to determine the rotational bearing capacity of the new type joint and to compare these results with theoretical values calculated according to Eurocode 5.