Effect of Fire on Epoxy‐Repaired Timber

Abstract

The use of epoxy repair for timber structures has proved to be both structurally efficient and economical. However, little information is available on the behavior of epoxy‐repaired timber during a fire. To evaluate this behavior for repaired truss joints, an experimental and theoretical investigation was conducted. The approach used was to: (1) Experimentally determine the epoxy‐to‐wood bond strength on small shear block specimens over a wide range of temperatures; (2) experimentally determine the time required for full sized epoxy‐repaired joints to fail when subjected to a sudden elevated temperature; and (3) develop a mathematical model which predicts the strength and duration of load for joints exposed to a sudden high heat condition. Based on a correlation of theoretical to experimental results, the theory was then utilized to obtain an approximate fire rating curve for epoxy‐repaired joints with glue lines at various distances from the exposed surface. A 30 min fire rating was obtained with the glue line at 3 in. from the surface and a 60 min rating was obtained with a glue line at 4 in. from the surface.