Finite Element Models for Predicting Moisture Effects on Bolt Embedment and Connection in Timber

Abstract

The mechanical performances of timber connections are particularly important for timber engineers involved in the design of the wood structures. The mechanism of connection must be well understood in order to design a safer connection and avoid catastrophic failure. Often connections are made weak fuse elements by deliberate intent to ensure that if structural systems fail it will be by controllable ductile deformation of connections in load paths. Model method of determining engineering design capacities of laterally loaded dowel fasteners, such as bolts, screws and nails was developed.  It should however be pointed out that FE and similar continuum model results always over predicted capacities at particular levels of deformation relative to experimental values. This result was expected and reflects the well-known inability of such models to incorporate all energy sinks that exist in experiments. The primary findings of the work reported is that it is highly viable to predict even complex effects that treatments like post-fabrication moisture conditioning have on responses of bolted glulam connections. Uniqueness of what is presented lies in the analysis of the combined influences of moisture content and mechanical loads by numerical methods.  This makes such models viable means of supplementing physical test data and analyzing of highly complex timber connection situations.