324
3665.002
Editors of Concrete Products
Concrete Products
Article
Maclean Hunter Publishers
1963
May
37-43
United Filigree Truss Corp., already has 14 Eastern block plants signed up as distributors.The Filigree system is similar in many ways to the Omnia. Both are German in origin; both use joists that combine a bottom chord encased in concrete with an exposed top webbing; both rely upon wide-flange filler block.
The Filigree system uses machine-made filler block that are manufactured in depths of 4, 6, 8 and 10 in. Widths are all the same: 19 1/2 in at the bottom with 7/8-in flanges on either side. All units have flat soffits, but the 10-in. block is also available with a curved soffit. Each of the block, made with lightweight aggregate, is said to use concrete with a compressive strength of 2,500 psi.
The girders are composed of a top chord, a continuous 5/16-in. diam. web and two high-strength steel bars. These bars provide the tensile reinforcement required in the live load design of the system, and can be two #4 bars, two #5 bars, two #6 bars or any combination thereof. The girders are resistance-welded at all intersections and are madd produced on a highly efficient, precision machine that transforms the raw steel into a lightweight member of continuous length.
Girders are sheared to the exact length required by the architects’ drawings for the particular job. The machine also cold-works the raw steel for the bottom chords in order to raise the yield point of the material, thus affording greater economy in design. The bottom portion is encased in a 2 1/4 x 4 1/2-in. concrete joist. The girder is available in 4.5, 6.3 and 8.5 in. depths, to provide total floor-and-roof thicknesses of 6 to 12 in. With the concrete foot attached, the joists weigh about 12 lb per linear foot.
Block are laid between the joists dry, and concrete topping placed to bond the entire system together. Temporary shoring is required if the joists are to span more than 7 ft. Under 7 ft., the girders will support their own weight and the weight of both the filler block and the toplayer of concrete.
Service installations are easily installed and holes for conduit can be drilled into the block with a regular masonry drill. If desired, varying heights of block can be used to accommodate two-way duct systems.