The Predictive Model for Load-Carrying Capacity of Inclined Screws as Connecting-Links in Timber-Concrete Composite Beams

Abstract

This paper briefly reviews the load-carrying capacity predictive models for dowel-type connectors in timber to timber connections as well as composite timber to concrete connections. The short analyses based on existing theoretical and experimental investigations of researchers showed that the connections with inclined screws possess the greater load-carrying capacity and stiffness as those with perpendicular to the shear plane arranged fasteners. Analyses of existing predictive theoretical models represented by numerous authors have showed that there is no computational model for connections with inclined screws and in practice only the empirical formulas and only for particular screw type may be used. Recently the calculation methods for dowel type connections as well as for screws are based on Johansen’s (1949) theory. This model lets to determine the load carrying-capacity very well for bolted or nailed connections, and only satisfactorily for screwed connections. Another theoretical model of Кочeнов (1953) which was adopted in timber design codes in Russia is based on the limited value of deformation of compressed under the fastener timber grain, and enables to relate withdrawal deformation with embedding deformation. In this paper the theory of Кочeнов was extended and applied to timber to concrete connections with inclined screws; the possible failure modes are described, equations for load-carrying capacity derived, and the main characteristic parameters for connection are determined. The theoretical model assessed with experimental results also carried-out by other researchers.