| 摘要 |
Hollow structures stiffened by incorporation of a thin-wall steel tube held in position by a cast jacket of rigid polyurethane foam (density of 40-50 kg/m3). Esp. for constructing ladders, boats, furniture from modified ABS or PVC profiles, or for prefabricated metal beams or rafters. To obtain increased stiffness with less (1/6-1/10) weight increase than that resulting from simply increasing the wall thickness of the primary construction material. |
