GB495474A - Ferro-concrete girder - Google Patents

Abstract

495,474. Girders; bridges. FINSTERWALDER, U. Feb. 11, 1937, No. 764. [A Specification was laid open to inspection under Sect. 91 of the Acts, July 12, 1937.] [Classes 20 (i) and 20 (iv)] A reinforced -concrete girder for bridges and other structures comprises concrete beam sections which are divided by joints and connected in end-toend relation by one or more tension bands which are secured at each end to the girder, and intermediate their ends, are disposed in movable engagement with, and externally of, ribs or walls of the girder. The girder shown in Figs. 1 and 2 comprises two sections a, b which are separated at c and provided with lead interlays in the joint. Each section comprises a continuous upper plate, longitudinal side webs g, and transverse ribs h ; the upper plate is arched on the underside between the ribs h. The tension bands d are anchored at each end in the girder by plates embedded in the girder ; alternatively, the ends of the bands may pass through the ends of the girder and be screwthreaded for engagement by nuts. The tension bands may consist of iron rods or bar, or members built up of iron strips or bars. The bands engage beneath the transverse ribs h which are provided with roller-bearings i for contacting with the band; the roller-bearings have horizontal races, and some or all of the bearings may be vertically adjustable. The band may be sheathed in concrete after erection of the girder, and preferably after being placed under additional tension by applying a load to the girder. In the modification shown in Fig. 3, the beam m is supported at both ends and co-operates with an overhanging arm n which is separated from the beam m by a joint c<1> provided over a support o. The tension bands d<1> extend from end to end of the complete girder. Both the beam m and arm n, consists of a track plate p, longitudinal side webs g<1>, transverse webs h<1>, and a lower plate p<1>. In some cases mere severance, or almost complete severance, of the cross-section at a determined point of the beam will serve to form the joint.