Utilization of prefabricated roof elements in the stiffening of timber halls

Abstract

The use of prefabricated roof elements in the construction of timber-framed halls is nowadays very common and cost-effective. Typically, roof elements are designed so that they also serve as stability supports for the main beams. This study deals with a design method in which the roof elements would be designed to function as part of the stiffening system of the entire building. A similar stressed-skin design method has long been used in steel-framed hall buildings, and in this article the method is modified to suit the specifics of wood construction as well. The article examines the horizontal load against the long side of a wooden hall, which can be considered as a basic case of stiffening calculations. Roof diaphragm action is obtained by using commonly used plasterboard which is screwed to the wooden frame. The results indicate that the diaphragm action of the roof has a large impact on the horizontal loads of the frame columns as well as on the horizontal displacements of the roof. The horizontal loads and buckling lengths of the columns are significantly reduced, compared to the case where the mast columns alone would carry the horizontal loads of the building. When the roof diaphragm action is taken into account in the design, the buckling length of the frame columns are reduced by up to 47 percent, compared to mast column stiffening alone. The results are similar to those obtained in the calculations of steel-framed halls. The method presented provides the basis for a more advanced and more realistic, economic design of timber-framed halls, even at no additional costs compared to the current practic.