省力化を目指した鉄骨梁耐火被覆工法の開発
本開発では、巻付け耐火被覆材を用いた鉄骨梁の耐火被覆工事の省力化を目的として、材料と工法の両面から従来技術の改良を試みた。具体的には、鉄骨梁の熱容量の有効活用、火災時に温度上昇しやすい下フランジの被覆のみの厚肉化、および耐熱ロックウールの高密度化などに関して検討を行った。その結果、耐火性能および省力化の観点から、耐熱ロックウールの高密度化による薄肉化が最も簡易で効果的であることが確認された。本開発により、従来よりも被覆厚さを薄くした2 時間耐火および3 時間耐火の認定を取得した。
Development of Fire-Resistant Covering Method for Steel Beam Aiming at Labor Saving
-Thinning of winding type fire-proofing covering materials-
In this development, an attempt was made to improve the conventional technology in terms of both materials and construction methods with the aim of saving the fire-resistant covering work using the winding type fire-proofing covering materials for steel beams. Specifically, we examined the effective use of the heat capacity of steel beams, the thickening of only the lower flange covering, which tends to rise in temperature during fire, and the densification of heat-resistant rock wool. As a result, it was confirmed that the thinning of heat-resistant rock wool by increasing the density was the simplest and most effective from the viewpoint of fire resistance and labor saving. As a result of this development, two-hour and three-hour fire-resistant structures with a thinner covering thickness than conventional ones have been certified.