Temperature distribution within glued laminated timber during a standard fire exposure test

The purpose of this study was to investigate the temperature distribution within glued laminated timbers (glulams) made from five softwood species as determined by a standard fire exposure test (CNS12514). The results reveal that the temperature within the middle section of tested glulam increased with increasing fire exposure time. After a fire exposure of 30 min and 45 min, the average temperature in the center of middle section for tested glulams (with a cross-section of 266 mm in depth × 190 mm in width) ranged from 27.5–28.3 °C to 29.5–33.2 °C; whereas, the average temperature for tested glulams (with a cross-section of 266 mm in depth × 140 mm in width) increased rapidly (from 32.3–51.1 °C to 39.1–89.3 °C) with an increasing exposure time and a decreasing cross-section. It was also found that the temperature in the center of the middle section increased slower than that in the right side or left side of a glulam middle section. The temperature within glulams (78 mm from the surface) remained constant without significant influence of fire exposure time according to CNS 12514. It can also be observed that equations developed by the Swiss Federal Institute of Technology give a closer calculation for the temperature development in tested glulams with heat flux from three sides.