GB776566A - Improvements in or relating to a lattice girder for building and like construction purposes - Google Patents

Abstract

776,566. Metal girders; reinforced concrete beams; floors. KAISER, W. Nov. 24, 1954 [May 3, 1954; Aug. 11, 1954], No. 34088/54. Classes 20(2) and 20(4) A lattice girder comprises (Fig. 3), a flat metallic strip 1 from which structs are struck out and shaped to have portions 3 lying at an angle to one another and to the strip 1 and a portion 4 lying parallel to the strip 1 and over the slots formed in the strip, an upper boom consisting of a rod 10 being secured, e.g. by welding, to the portions 4. As shown in Fig. 5, the girder may comprise two flat metallic strips from which struts are punched out, the flat portions 4 and 14 of the struts being secured to a common member 12. In a further modification four strutted booms of the type shown in Fig. 3 are arranged in two pairs at right angles to form a box girder, the flat portions of the struts of each pair of booms being welded to each other, the welding points of one pair being staggered relatively to the welding points of the other pair. Concrete can be poured into the box girder to cover all the iron parts. In Fig. 9 the girder is constructed from. a strip of U-section, the limbs of the U having inturned flanges 25 to which are welded the flat portions 4 of the struts struck out of the flat base of the strip. In the modification of Fig. 11 the struts of a lower boom 33 are so spaced that the struts of an upper boom 35 can be accommodated as shown without the struts of the two booms contacting one another. As shown in Fig. 15 the strips forming the upper and lower booms 51 and 52 are corrugated and the apex portions of the struts struck out from these booms when welded to each other form a circular opening 69. Beams of the type shown in Fig. 5 may be used for constructing floors. The beams comprise strutted booms 41 and 42 (Fig. 12), secured to a common member 45 and are placed in spaced parallel relationship, the edges of the members 45 supporting slabs 47 and the upper boom 42 lying in the joint between two slabs. The upper boom is strengthened by a bar 46 and the joints between the slab are filled with concrete.