| 摘要 |
1496736 Structural beams; reinforced concrete floors HAMBRO STRUCTURAL SYSTEMS Ltd 23 May 1975 [11 June 1974] 22552/75 Headings E1K, E1S and E1W In a metal joist having a top chord 5 or 45, a bottom chord 7 or 47 and a web which may be either a zig-zag rod 3 or a flat sheet 43 integral with the chords, the top chord includes an upper portion 9 or 49 of upright S cross-section and a lower portion connected to the web, the S shape being offset in one direction from the plane of the web and the lower portion including a horizontal flange 17 or 55 extending in the other direction from the plane of the web, and the cross-section of the top chord between the base of the S and the flange including an inclined step 11 or 51. Typically the step is connected to the flange by a shelf 13 or a shelf 53 which overlies the flange. The bottom chord may be formed by a pair of back-toback angles 19, 21 or may be integral with the web and of oval cross-section. Slots for receiving spacer bars 25 or 59 may be provided in the upper chord or in the web, the bars being provided with handles 37. Additional support bars 61 may space the bars 59. Sheets of plywood are placed over the spacer and support bars and are sized to fit beneath the inclined steps 11 or 51 and force the joists apart, mesh reinforcement is placed over the joists and concrete is poured on to the plywood to cover the reinforcement and the top of the joists. When the concrete is sufficiently set the spacer bars are twisted through 90‹ and removed together with the support bars 61 and the plywood. |
