Abstract: A first and a second element have respective abutting surfaces which together form an interface. One or more connecting members, such as screws, rivets or the like, connect the elements together. The juxtaposed sides of the elements are formed with respective matingly inter-engaging projections and recesses which resist forces that are being transmitted between the elements and act in the plane of the interface. The invention is especially advantageous for use in erecting trusses or arches of halls and other buildings, and in such a case the elements may be structural plates having the recesses and projections grouped about the locations of the respective connecting members.