Abstract
According to Japanese Building Standard Law, 2-hour fireproof floor slabs and walls are needed to construct over 4-story buildings. To develop the 2-hour fireproof CLT structures, small furnace fire tests and actual-size fireproof tests were conducted for CLT specimens cladded with some refractory materials. Small furnace fire tests were conducted to demonstrate the fire resistant properties of CLT cladded with calcium silicate boards, gypsum boards, and these combinations. Actual-size 2-hour fireproof tests were conducted for the cladded CLT floor slabs combined with a steel beam. From these tests, the following were indicated; CLT cladded with calcium silicate board （JIS A 5430 Calcium silicate board Type3, 0.5TK） 15mm （outer） and gypsum boards （JIS A 6901 GB-F） 45mm （inner） had adequate 2-hour fireproof performance. Heat conduction of screws to fix the outer claddings did not cause charring of CLT when claddings had adequate 2-hour fireproof performance.Further thermal insulation on steel member subjects or some artifice around the CLT-steel joint region should be done if CLT and steel members used together.
