The relationship between stress wave transmission characteristics and the compressive strength of biologically degraded wood

Wood in service can be attacked by a variety of biological organisms. Such organisms feed on the constituents of wood, thereby reducing its ability to carry load and serve in an engineering capacity. This paper presents the results of a study that investigated the use of longitudinal stress wave nondestructive evaluation to assess the strength of wood members exposed to biological attack. Clear southern pine specimens were exposed to attack by wood-destroying decay fungi and termites under field conditions in southern Mississippi. The speed of stress wave transmission and attenuation characteristics of the specimens were determined using longitudinal stress wave techniques after exposure. These nondestructive parameters were then incorporated into a multivariable regression model and used to predict the parallel-to-grain compressive strength of the specimens. Excellent agreement was found between predicted and actual compressive strength values.