| 摘要 |
A sheet metal section, comprising an upper flange (2), which at its upper edges passes into two webs (3) which are sloping relative to said section and formed with stiffenings (7), each web passing at its lower edge into an outwardly bent lower flange (4). The upper flange (2) is substantially wider than the lower flanges (4). To achieve simpler manufacture of said section (1) and improved rigidity, strength and buckling resistance, the centre portion of said upper flange (2) is substantially arched in cross-section, said arch bulging upwards relative to said webs (3), and said upper flange (2) comprises, at its junction with each web (3), a stiffening fold (9). The transition between the upper flange (2) and each web (3) preferably comprises also a stiffening ridge (8) extending in the longitudinal direction of said section (1). |
