The Prediction of Timber Bridge Girder Strength

This paper links past and current research to demonstrate how the structural integrity of timber beam bridge girders can be managed and maintained more effectively. There are a large number of timber beam bridge girders in use on local roads throughout Australia, for which the condition is not well known. For the last decade or so there has been a lack of funding to enable these girders to be maintained in an 'as new' status. The condition of some timber bridges is such that low load limits have been applied because of the difficulty to quantify both the current traffic loads and the girder strengths and not necessarily because the structure is known to be unsafe. Previously measured data, published by others, are evaluated and comparisons made of aged girders comprising a variety of conditions and ages. The wide variation in the values for Modulus of Rupture (MoR) and Modulus of Elasticity (MoE) among the pooled results of previous measurements has not enabled the variation of these parameters to be readily identified for a particular girder. It is inferred from this study that MoE can be used as an indicator of a particular girder's potential MoR and thereby enable useful in-service measurement systems to be created.