Evaluation of Simplified Methods of Analysis for Timber Bridges

Abstract

The design of timber bridges in Canada is carried out in conjunction with the Canadian Highway Bridge Design Code. A key feature of this code is the ability to employ a Simplified Method of Analysis (SMA) to determine the forces acting on a bridge and its various members. Since its introduction in the early 1980's, the SMA's development had been largely governed by steel/concrete bridges, rather than timber. As a result, for short-span timber bridges, the SMA is markedly over-conservative. Due to the SMA's over-conservatism when applied to such bridges, it identifies (often incorrectly) that many timber bridges do not satisfy code requirements. This thesis presents a research study to (a) evaluate key parameters on the overall bridge and bridge member force distribution, and (b) develop a new method for accurate (yet, still safe) evaluation of short-span timber bridges that can consider these factors.