Design of Notched Wood Beams

Abstract

Current design methods for notched wood beams, based on either notch‐factor or linear‐elastic fracture mechanics (LEFM) approaches, are reviewed and compared with an alternative equation based on critical fillet hoop stress (CFHS) theory and with experimental data. The CFHS and LEFM equations are shown to account for the observed effects of notch corner location, load distribution, beam height, and fractional notch depth. The notch‐factor equation, currently the basis for U.S. design practice, does not reflect the effects of beam height and notch corner location on strength. The CFHS equation implicitly accounts for the effect of beam span‐to‐depth ratio, and was developed from combined results of finite element and statistical analyses and an extensive experimental program. Other potential advantages of the CFHS equation are: (1) Its ability to account for stress relief caused by rounding the notch; (2) its ability to account for Saint‐Venant end effects for notches located at, or close to, the support; and (3) its use of a notched beam material parameter κ that is easily determined by simple tests.