Steel Buildings in Europe

Part 1: Architect’s Guide 1 - 19 There are numerous options for the beams:  Hot rolled sections (I-beams)  Plate girders  Fabricated beams with holes in the webs  Trusses Hot rolled I section beams The most common type of beam and column structure uses hot rolled steel I sections for both beams and columns. These sections are produced in accordance with international standards and there are design tables available to allow for an easy selection of section size to suit the loading. The most common section sizes are readily available from stockists and can be ordered at short notice. Deep sections with relatively narrow flanges are preferred for roof beams, as shown in Figure 3.12, where they primarily resist bending. Columns, which primarily resist compression, are usually thicker, shallower sections with wider flanges. The span/depth ratio for the roof beams is typically 30 to 40 for spans up to 20 m. Figure 3.12 Pinned frame beam and column structure Plate girders Plate girders are built up beams consisting of two flange plates, welded to a web plate to form an I-section. This type of beam offers a solution when the standard I and H beams are not suitable. The section dimensions are chosen to suit the design bending moments and shear forces; the beams can be profiled in elevation, as shown in Figure 3.13. The span/depth ratio is typically 20 to 25 for spans up to 30 m. An alternative that is sometimes used for large spans, to reduce the thickness of the web plate, is the use of a corrugated plate (profiled in plan). The span/depth ratio with a profiled web plate is typically 30 to 40 for spans up to 100 m.