A three-dimensional model for bolted connections in wood

Abstract

Recent criticism of the bolted connection requirements in the Canadian wood design code CSA Standard O86 indicates that the code lacks consideration of the different modes of failure, particularly as they relate to multiple-bolt connections. A finite element model is proposed to predict load–displacement behaviour, stress distributions, ultimate strength, and mode of failure in single- and multiple-bolt connections. The three-dimensional (3-D) model uses anisotropic plasticity for the wood member and elastoplasticity for the bolt. The Weibull weakest link theory is used to predict failure at given levels of probability. Predictions for connection behaviour in Douglas-fir and laminated strand lumber (LSL) correspond to experimentally observed behaviour. The output from the 3-D model is used for a multiple-bolt connection spring model to illustrate many of the phenomena described in the literature.Key words: bolt, Douglas-fir, connection, model, plasticity, weakest link, wood.