Analysis of Mechanically Laminated Timber Beams Using Shear Keys

Abstract

Small timber layers can be mechanically laminated into a larger timber cross section using shear keys to prevent slip between the layers. These mechanically laminated beams are commonly referred to as keyed beams and their use has a strong historical precedence. Current building codes and design standards do not provide adequate guidelines for the analysis of keyed beams. This project examined the applicability of an interlayer slip model to predict the partially composite behavior of the keyed beams. Solutions to the interlayer slip model for common loading configurations were developed, as were stiffness parameters for the semirigid wooden shear keys used to provide composite action. Small and full-scale testing of timber components was also performed to verify the interlayer slip model’s ability to predict the stiffness of specific keyed beam specimens. A comparison of the interlayer slip model to historical keyed beam test data was also conducted. The interlayer stiffness model, as well as the analytical shear key stiffness parameters, was able to accurately predict both the behavior for the full-scale keyed beams tested specifically for this research as well as the historic keyed beam behavior. Shear key configuration, moisture content, and clamping connector stiffness all played significant roles in the actual keyed beam stiffness.