Structural behavior of glued-laminated timber beams with notches at the support or with holes

Abstract

Notches or holes can reduce the load-bearing capacity of glued-laminated (glulam) timber beams considerably. Notching can be necessary for architectural reasons and service installations may require holes in the beams. Close to notches or holes multi-axial stress peaks occur. Because of the very low tensile strength perpendicular to the grain as well as the low shear strength of timber, reinforcement of the notch or hole is often required. Therefore, for the design of the reinforcement, the load-bearing capacity of the unreinforced timber beam has to be known.

Existing design approaches are based on empirical studies or theoretical fracture mechanical analysis. The load-bearing capacity is mainly influenced by the geometry of notch or hole and the material properties of the wood. Further, service and climate conditions have an important impact on the material properties and have to be taken into account.

The project aims are the development of basic input data and calculation models for the design of glued-laminated timber beams with notches at support or with holes. The models to be developed will improve the design of glued laminated timber members with regard to safety and economy.