The Effect of Biological Deterioration on the Seismic Performance of Woodframe Shearwalls

  This article describes a combined experimental and analytical investigation of the effect of biological deterioration on the performance of light‐frame wood shearwalls subject to seismic loading. Deterioration due to fungal attack is believed to have a significant effect on the displacement and capacity performance of light‐frame shearwalls. Some studies have shown that fungi tend to degrade properties of nailed connections common in light‐frame structures, however, the effect on shearwall assemblies has not yet been quantified. The effect of biological deterioration (due to fungal attack) on cyclic performance of light‐frame shearwalls was evaluated in this study by, first, fitting sets of hysteretic model parameters to single fastener sheathing‐to‐framing connections exposed to different levels of decay from brown rot fungi. Next, these model parameters were used as an input to a numerical model used to evaluate the cyclic behavior of complete shearwall assemblies. Finally, the output from this model was used in a nonlinear dynamic time‐history analysis to evaluate displacement response of the shearwalls subject to a suite of ground motion records. The results were presented in the form of peak displacement distributions and fragility curves.