Load and Resistance Factor Design of Timber Joints: International Practice and Future Direction

Abstract

International practice for load and resistance factor design (LRFD) of mechanical structural timber joints is reviewed. Attention is on design provisions in the U.S., Canada, Europe, and Australia, those being locations where LRFD codes for wood construction exist. There are broad similarities between various codes, in that all countries adopt an element-based approach to design. Most codes base capacity design checks for joints with dowel-type fasteners on the so-called European yield model. There are a number of systematic differences in detailed implementation of LRFD concepts between countries. No country has yet used structural reliability concepts in derivation and/or calibration of design equations for joints as the level of safety cannot be formally assessed except for relatively simple problems. This contrasts with the situation for members, as several countries have already implemented reliability concepts in design of wood members. Thus, there is imbalance in the principles of design for members and joint in timber systems. Suggestions are made regarding actions necessary to place member and joint design on an equal footing.