Design methodology of total timber 2-hour fire-resistive structural beam on sacrifice layer concept

This study indicates the design process through three kinds of fire tests on the total timber 2-hour fire-resistive structural beam. The typical structural element is composed of two layers and structural part: the first is sacrifice layer (chemically untreated wood), the second is barrier (fire-retardant treated wood), and the structural part is on the center of the element and promised load-bearing role (chemically untreated wood). The design process is based on (1) bench-scale fire tests, (2) unloading real shaping beam fire test, (3) loading full-scale fire test. Three kinds of fire tests cleared the correspondence of test results mainly regarding of Non-damage ability and Self-extinguish ability. (1) Bench-scale fire tests clarified required fire-retardant performance and thickness of the barrier as for the element reproducing side section which was heated from only one side. The series (2) fire test found that the corner section was carbonized nearly twice deeper while cooling than the side section. Then, the unloading real shaping beam needed 25mm thicker barrier to prevent the entire load-bearing part from carbonizing than the optimum specification in series (1) tests. The series (3) tests discovered the possibility of the glowing combustion continuation with different mode by bench-scale tests mainly due to delamination involved in loading. This engineering approach through various scaled fire tests is one of signposts to design a fire-resistive timber beam on a sacrifice layer concept.