| 摘要 |
PROBLEM TO BE SOLVED: To ensure a sufficient strength, to reduce weight and a cost, and to facilitate a proceping and assembly work. SOLUTION: A ceiling joist 15 is provided with cylinder parts 151 made of light iron arranged at an upper and a lower part. The ceiling joist 15 is attached to an upper beam 12 through a stiffener 154 and fixed at a bracket 153 protruded from the inner edge of the upper beam 12. Since the ceiling joist 15 improves rigidity in terms of structure compared with a square pipe, even when light iron is used, a sufficient strength is ensured and weight and a cost can be reduced. Further, a processing and assembly work is also facilitated. |
