PROCEDIMIENTO PARA CONSTRUIR VIGAS DE CELOSIA.

摘要

1,152,554. Making lattice girders; altering physical structure. J. G. S. KELLER. 4 May, 1967 [13 May, 1966], No. 20827/67. Headings B3A and B3V. [Also in Division E1] In order to improve the strength of a steel lattice girder for reinforcing concrete floors, the lattice web portions 171 other than at the bottom chord or chords 111 are hardened by cold working. The girder is made by first forming equidistant spaced loops 14 in a steel rod and clamping the loops in slidable vices. The portions of the rod between the clamped loops are pressed by a wedge shaped ram to form a sinuously extending lattice 131, the vices moving towards each other a limited distance, whereupon further movement of the ram causes the portions 171 to be strained preferably by about 5%. The peak portions of the lattice 131 may also be clamped to avoid straining in these areas. The unstrained loops 141 of the lattice are finally electric resistance welded to two spaced apart bottom chord rods 111. A channel section top chord (12) (Fig. 1, not shown), may also be welded to the peaks of the lattice 131. The lattice 131 may alternatively be formed from individual components or from a rod having alternate strained and non strained portions.