State-of-the-Art Review of Approaches for the Design of Timber Beams with Notches

Abstract

Notches are details that significantly reduce the load-carrying capacity of beams made of timber. The amount of reduction was the subject of investigation in numerous studies from an experimental or theoretical point of view. The singular stress distribution around the notch corner can be described by equations based on linear elastic fracture mechanics, fracture energy, or complex solutions. From experimental tests, simplified equations can be proposed. Standards, codes, and handbooks for the design of timber structures are based on such equations. When comparing the dimensions of notched beams tested in experiments with those that are relevant in practical applications, specimens of small dimensions were primarily tested. The application of design approaches verified by tests on specimens of small dimensions and the use of material properties determined from small clear specimens do not account for size effects that are important when working with beams of large dimensions. The influence of duration of load, moisture variation, and cyclic loading on the fracture of the notch has to be studied. An extension of tests on notched beams and relevant material properties that are now gained from small clear specimens to those of large dimensions is necessary.