Keiichi Miyamoto

Drill and laser incising of lamina for fire-resistive glulam

Abstract Conventional glued-laminated timber (glulam) was not permitted to use to a wooden building in the fire preventive district since the amendments of the Building Standards. We already developed a one-hour fire-proof glulam made of Japanese cedar. We also succeeded to give one-hour fire performance to cross laminated timber by the same concept. The both structures are composed of three parts which are load-bearing part, fire-die-out part and surface part. The fire-die-out part is made of lamina incised by CO2 laser and impregnated the fire retardant evenly. As the handling of CO2 laser is not so easy for glulam manufacturer, we felt a growing need for drill incising technology. Therefore, we made pinholes of some diameters up to 2.5u2005mm to lamina of Japanese cedar, by a drill and investigated differences of hole position on two sides of the lamina. The maximum off-center for length and width directions was 1.8 and 3.3u2005mm, respectively. These off-centers are 2.3% and 41% of distances between neighboring hole on incising patterns. As the results of impregnating performance and fire-resistive performance of lamina incised by drill, significant differences were not recognized between drill incising and laser incising.

BURNING BEHAVIOUR ON FIRE-PREVENTIVE GLUED LAMINATED TIMBER OF SEVERAL COLUMNS

The Japanese government is promoting use of wood in recent years, because of the environmental provision of carbon dioxide fixation. The authors developed “FR wood”. “FR wood” is the only technique with simply use one tree species in Japan. “FR wood” is built by three layers. The central member supports load, the second layer prevents a fire and the third layer is surface. A lot of experimental cases were conducted, and many temperature data or carbonization thickness data were accumulated. The measured maximum temperature depended on the thickness and the tree species of load supporting member.