Unbonded post-tensioned timber gravity frames for multi-storey buildings

This paper describes the use of post-tensioning for long span timber gravity frames. These frames can be used for multi-storey commercial and office buildings. Two different configurations are described, one with prefabricated post-tensioned timber beams and one with post-tensioning through the full length of the frame. In the latter, beam-column connections are created by the clamping force due to the post-tensioning. It is shown that post-tensioning of timber beams can create a precamber which helps to satisfy deflection criteria. This makes it possible to create long span timber beams while limiting the section height. Key design issues including deflections, tendon profile, deviators and tendon anchorage are addressed. The behaviour of these connections is presented and the three deformation components of the connection are explained. A design example of a post-tensioned timber frame is also included.