SECTION 812 - STEEL GRID FLOORING
812.01 Description. This work consists of constructing steel grid flooring, open or
concrete-filled type as specified, in accordance with these specifications and in reasonably close conformity to the lines and grades shown on the plans or established.
812.02 Materials. Materials shall conform to the provisions of Subsection 717.05.
812.02.1 Arrangement of Sections. Where the main elements are normal to centerline
of roadway, the units generally shall be of such length as to extend over the full width of the roadways up to 40 feet, but in every case the units shall extend over at least three panels. Where joints are required, the ends of the main floor members shall be welded at the joints over their full cross-sectional area or otherwise connected to provide full continuity. Where the main elements are parallel to the centerline of the roadway, the sections shall extend over at least three panels, and the ends of abutting units shall be welded over their full cross-sectional area or otherwise connected to provide full continuity in accordance with the design.
812.02.2 Provisions for Camber. Unless otherwise provided on the plans, provision for
camber shall be made as follows: (a) Steel units so rigid that they will not re adily follow the camber required shall be cambered in the shop. To provide a be aring surface parallel to the crown of the roadway the stringers shall be canted or provided with shop-welded beveled bearing bars. If beveled bars are used, they shall be placed along the centerline of the stringer flange, in which case the design span length shall be governed by the width of the bearing bar instead of by the width of the stringer flange. (b) Longitudinal stringers shall be mill cambered or provided with bearing strips so that the complete d floor after dead-load defl ection will conform to the longitudinal camber shown on the plans.
812.02.3 Welding. All shop and field welding sha ll be in accordance with Subsection
810.03 5.
812.02.4 Repairing Damaged Galvanized Coatings. All galvanizing that has been
chipped off or damaged in handling or transporting or in welding or riveting shall be repaired by field galvanizing by the application of a paste composed of approved zinc powder and flux with a minimum amount of wa ter. The places to be coated shall be thoroughly cleaned, including removal of slag on welds, before the paste is applied. The surface to be coated shall first be heated with a torch to a sufficient temperature so that all metallics in the paste are melted when applied to the heated surface. Extreme care shall be taken to see that the galvanized surfaces are not damaged by the torch. The flux in the paste will cause a black substance to appear on the surface of the coat ed parts, and this black substance shall be removed by wiping off with waste or by the quick application of cold water.
812.03 Construction Requirements.
812.03.1 Field Assembly. Areas of considerable size shall be assembled before the floor
is welded to its supports. The main elements shall be made continuous, and sections shall be connected together along their edges by welding of bars or by riveting them. The connections shall meet with the approval of the Engineer. The rivets may be cold driven.
812.03.2 Connection to Supports. The floor shall be connect ed to its steel supports by
welding. Before any welding is done, the floor shall either be loaded to make a tight joint with full bearing, or it shall be clamped down. The location, length, and size of the welds shall be subject to the approval of the Engineer, but in no case shall they be less than the manufacturer's standards. The ends of all the main steel members of the slab shall be securely fastened together at the sides of the roadway for the full length of the span by means of steel plates or angles welded to the ends of the main members, or by thoroughly encasing the ends with concrete.
812.03.3 Concrete Filler. Floor types with bottom fla nges not in contact shall be
provided with bottom forms of metal or wood to retain the concrete filler without excessive leakage. Metal form strips, when used, shall fit tightly on the bottom flanges of the floor members and be placed in short lengths so as to extend only about one inch onto the edge of each support, but in all cases the form s shall be such as will result in adequate bearing of slab on the support. The concrete shall be mixed, placed, and cured in accordance with Section 804. The concrete shall be thoroughly compacted by vi brating the steel grid floor. The vibrating device and the manner of operating it shall be subject to the approval of the Engineer.
812.03.4 Painting. Flooring furnished without galvanizing but with a shop coat of paint
shall be given field coats of paint in accordance with Section 814. When a structural steel plate is used on the bottom of a filled type floor, the bottom surface of the plate shall be given one shop coat, one field intermediate coat, and one field top coat of paint in accordance with Section 814.
812.04 Method of Measurement. Steel grid floor of the type specified will be measured
by the square foot complete in place. No separate measurement will be made for galvanizing or painting and concrete filling when required.
Steel Grid Flooring in other states
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