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HomeMy WebLinkAboutOrdinance 1514 ORDINANCE N0. ING�CODE ORDI�MME#1389 BYAADDING SSECTIOOF N 15-24 THERETO, PERTAINING TO STEEL JOISTS C OUSTRUCT ION. BE IT ORDAINED BY .THE CITY COCNCIL OF THE CITY OF FORT WORTH, TEM; SECTION I. That Chapter 15, Section 15-24 of the Building Code Ordinance #1389 or the City of Fort Worth, shall hereafter read as follows: "CHAPTER i5. Section 15-24 STEEL JOIST Paragraph 15-24-1 . Steel Joist.--Steel joists shall be considered as secondary memoers of the structural steel or reinforced cLnerete frame. They shall be designed to carry all deal, live, and other loads to which they mVLy be sub j ected during the erection and after the cumpletion of the structure. Such secondary members shall not be considered as affecting the vertical rigidity of the framework, but they shall be designed and considered as carrying horizontal forces to the adjacent line of columns and each line of columns shall be designed to carry these horizontal forces directly to the ground. Construction.-- Steel joists may be electric welded structural sections, sections built up of rolled structural sections, expanded structural sections, or shapes made from strip or sheet steel securely spot welded together so as to fu m a cu- hesive structural unit all of wnicn shall have the general shape or cLatour of an I-beam; or such steel foist may be of a determimte truss design built up of rolled structural shapes effectively electrically welded together as hereinafter specified. Stresses.-- Stresses in steel joist snail not exceed those specitiedrin/Paragraph lb-3-1 of this Code and no joist under its calculated load shall have a deflection exceeding one three-hundred-six- tieths (1/3bU) of its span. Lateral bracing or bridg- ing snail be iwtailed su'ffica ently to stay the foist. Such bridging shall consist of not less than fourteen (14) gage galvanized wire firmly attached to' both trop and bottom chords of the truss foist or beam flanges. The bridging shall be spaced not to exceed seven (7) foot centers. Before joists of other than the standard structural shapes are used the mamifac- turer of his representative snail submit to the Building Commissioner complete details and calcula- tions of stresses in the members. Such caica .Lations of stress snall also show the resistance to bending for each inch of length of the end seat where the seat is designed for multiple points of support and must also snow the resistance of the main members of the joist to eccentricity due to heal joist. Connection to Main Members.-- When steel foists are used in connection with structurai steel framing they shall be connected to the supporting beams or girders by electric arc welding, riveting, bolting, or rigidly connecting. Arc welds -snail be made on each side of end bearings and shall not be less than one (1) inch in length measuring from the starting end to the certer of the finishing crater, and shall have a minimum bead of one-fourth ('f) inch. When steel joist are supported on masonry the end beairing spall not be less tba.n four (4) inches in tergth. Anchors shall be provided at the end of every second truss or not more than tour (4) feet apart. Such anchors snail be attached to the truss by means of a proper hook or by bolting, riveting, or welding thereto and shall have a pin rigidly at- tacned to the horizontal bar or rod at the wail end and at right angles to the truss. In ccmputing the capacity of concrete beams carrying steel joists no consideration shall 'be givenc-totthitportion o Ize beam which may be above the bearing plate of the steel joists. The anchorage snail be so designed that it will not separate the concrete in the beam, but will provide positive and combined action of the beam and the truss. Strip or sheet steel used to produce strip steel joist shall in no case be (less than seventy-two thousandths (,U72) of an inch in thickness. 'Phe flange width of such foist shalt not exceed onehalf (t) btiitWIl&p*h. Trussed steel foist snail oe so constructed that the lines of force af,-ell�auinecting members snarl intersect at a point or proper allowance shall be made. in design for any resulting stress due to ec- centricity. Welding.-- '2he joints of all trussed joist shall be made by connecting the members direct ly to one another by electric arc welding or by rivets of suf- ficient capacity to develop4 the ultimate strength of the smallest connected member. Mechanical spot, fusion or resistance weldingtur Trutt welding shall not be used. When welds are used each connect ion of member to member shall be made with not less than two welds of sufficient length and cruss-section to develops the full strength of the memuers. I11 welding shall symetri cal on both sides of the con- nection. Proper penetration and fusion shall be secured and all joints shall be free from indents and out outs caused by the arc and the full section of the parent metal shall be maintained. Testing.-- Where truss foists have welded connec- tions each joint small be fully tested by approved methods and certificates of such tests shall be furn- ished with each shipment. Whenever deemed necessary by the Building Commissioner any steel truss joist with welded connections shall be tested to not less than twine the design load and such load shall be sustained -without any sign of failure and without the allowable deflection being exceeded. The use of welded steel joist construction shall be Lizited to structures in which the total uniform design load- ing does not exceed one hundred (100) pounds per square foot. The use of welded steel joist will not be permitted in construction where heavy con- centrated loads may be anticipated; i. e., for garage floors; for floors of heavy manufacturing or storage buildings or for ceilings from which heavy line shafts are to be suspended. Floor Slab.-- The floor slab for steel joist construction shall be of conitrete designed as speci- fied in 9hapter 17 of this Code, but in no case shall the thickness of the floor slab be less than two and one-half (2-k) inches. Fireproofing: The lower flange or chord of steel joist shall be fireproofed with metal lath and plaster. The metal lath shall consist of wire lath of not less than No. 2u gage wire or sheet metal lath weighing not less than three (3.0) pounds per square yard and such lath shall be applied in accordance with Section 11-2 of this Code. ?fetal lath shall be Kept at least three-fourths (t) inch below the bottom chord of the joist. Where furring is used to produce this required air space only metal furring will be permitted. The plaster shall be at least seven-eighths (7/8) inches in fin- ished thic=ess and shall be an approved cement plaster or prepared plaster having fire retarding qualities equal to cement plaster." SECTION II. That all ordinances and parts of ordinances here- tofore passed by the Clty Council of the City of Fort Worth vuaal shall conflict with the foregWxg provisions of this ordinance shall hereafter by null and void and of no further force and effect. SECTION III. This ordinance shall be in full force and effect immediately-after the giving of such notice as is re- quired by law: APP O D / O FORM __.......__................. .....OtL.t,.� r. ry s rr ou,c..