Compressive strength of lumber at high temperatures

A model was developed to predict the residual strength in compression parallel to grain for dimension lumber subjected to axial loads at elevated temperatures while braced to prevent buckling. Prediction of the time-dependent temperature profile within the cross-section of a lumber member was achieved by adapting a two-dimensional heat transfer model. An extensive literature review examined seven models proposed by various authors to predict residual strength under various temperature regimes. With knowledge of the temperature-history and material properties, it was possible to predict the time to failure by crushing of axially loaded members exposed to elevated temperatures. Initially, predicted times to failure did not show as good an agreement with those measured in an experimental programme as had been hoped. However, when a new residual strength-temperature model was developed and used to simulate the axial load capacity of nominal 38 mm x 89 mm studs exposed to fire, the results obtained showed good agreement with experimental results.