Loading...
HomeMy WebLinkAboutOrdinance - 742-1946 - Amend Ordinance No 587 - 01/24/1946c 0\ -2-4-1..94-{jJ l . ORDINAOCE NO. 7 4 2 AN OI\DINANCE AMENDING OR.DINA:OCE NUf.ffiER 587 BY ADDING PROVISIONS REGULATING LIGHT STEEL CONSTRUJTION; :PROVIDIOO CONSTROOTION DETAILS, AND TYPE ·OF WORK- MANSHIP, PAINTING AND ERWTION OF LIGHT STEEL FRAME WORK FOR TYPE FOUR BUILD- INGS , AND DECLARING AN El\BRGENJY. \iHEREAS, the City of Lubbock has no ordine,nce provision governing light steel construct·ion in d,etail and public safety requires adoption of uniform building requirements and'practices for Type Four Buildings, THEREFORE, BE IT ORDl.IWED BY THE CITY COllfHSSION OF THE CITY OF 'LUBBOCK: That Ordinance No. 587, entitled, 11An ordinance regulating the erection, construction, enlargement, alteration, etc., of buildings and/or structures in the City of Lubbock", BE and the same is hereby amended by adding the following provisions: LIGHT STEEL CONSTRIDTION Section 2720. {a) General. Steel studs and other supports used in the structural frame of light steel construction and steel joists shall be light weight rolled steel sections or sections formed from light gauge flat rolled steel sheets, or a combination of both used alone or in combination with · other materials of construction, all of which shall be of a standard or com· monly accepted type or shape; or such members may be of a determinate truss design built up of rolled structural steel sections effectively arc or re- sistance welded together. For such steel studs the ratio 1/r shall not ex- ceed 180. The effective width of flanges on such members having a channel section shall not exceed 20 times the thickness of the flange. The effective width of flanges on such members having an I-section shall not exceed 20 times the thickness of the flange on ea.ob side of the neutral axis. The effective width of steel sheets or plates constructed to act integrally with steel joists, studs, or other steel supporting members shall not extend more than 20 times the thickness of such sheet or plate on each side of the point or points of fixation to such members. Open web or trussed members shall be so constructed that the lines of force of all connected members shall intersect at a point or pDoper allow- e.nce shall be made in the design for e.ey resulting stress. The web elements s hall be of sufficient strength to resist effectively the shearing stres ses. The following are the minimum thicknesses of metal permitted for various members of the structural frame of light steet construction: Bearing studs, floor and roof framing members·-16 gauge Cellular steel walls, floor and roof panels--18 gauge Roof decks supp6rted on ribs--20 gauge All connections shall be riveted, bolted or welded. All steel work, in- cluding welds and connections, except where entirely encased in concrete, shall be thoroughly cleaned and given one coat of acceptable metal protec- tion well worked into the joints and open spaces. c (b) Stresses. Stresses in structural members of light steel construction shall not exceed those specified in Section 2702. No steel joist under its calculated load shall deflect more than 1/360 of the span, when plaster is ·supported. The actual spacing of floor joists, studs or other light steel wall supports shall be determined by their capacity to sustain the loads which they carry, but in no case shall such spacing exceed four feet (4 1 ). 2. (c) Construction Details. Steel studs or other steel s upporting members used in the structural frame of light steel construction and steel joists shall be connected to the supporting beams, girders, foundations or other steel sup- porting members by arc or resistance welding, riveting, bolting or other ap- proved methods. All such welds in light steel construction shall be made on two sides or two edges of each bearing in such a manner as to resist effect- ively the stresses developed. Resistance welding shall develop the full strength of the member welded. Steel floor and roof members supported on masonary and reinforced concrete shall have end bearings at least four inches (4") in length and the ends of. such members resting on masonar.y or reinforced concrete shall be provided with approved joist anchors thorough~ embedded therein. Bearing plates, when required by design, shall be securely welded, bolted or riveted to such floor and roof members, studs or other supporting members. Bearing studs or other vertical bearing members shall rest on a sole or plate having an effective width equal to the depth of such member and having a t~ckness of not lese than 14 gauge but in no case less than that of the vertical member resting thereon unless each such vertical bearing member is throughly embedded in the concrete foundation. Such soles or plates shall . be effectively anchored to the foundation and all splices and intersections shall develop the full strength of the members connected. When bearing studs or other vertical bearing members are spliced, the full strength of such members shall be developed in the splice. Where studs do not continue full length from one story through the next story above, a cap plate or steel member shall be provided on top of the low- er story studs or a sill plate on the apper story. Such cap plate or sill plate shall be of sufficient strength to distribute adequately the loads from the upper story studs to the lower story studs. All horizontal or diagonal ties or bracing in exterior walls and bearing partitions shall be effectively arc welded, bolted or riveted to the struc- tural frame or effectively anchored to supporting masonry. Where plumbing, heating or other pipes or conduits are placed in or part- ly in an exterior wall or bearing partition necessitating the cutting of soles or plates, bracing or structural member in said wall, such members shall be reinforced so as to provide s ufficient strength to resist the stresses imposed thereon or proper provisions shall be made to &Jansfer wch stresses to the points of support. Section 2721. Expansion. ~oper provision shall be made for expansion and contraction. - c 0 Section 2722. Workmanship~ All workmanship shall be equal to the best practice in modern structural shops. Drifting to enlarge unfair holes shall not be permitted. Holes that must be enlarged to admit the rivets shall be reamed. Poor matching of holes shall be cause for rejection. 411 material shall be clean and straight. If straightening or flattening is necessary, it shall be done by a process that will not injure the material. Sharp kinks or bends shall be cause for rejection. Rolled sections, except for minor details, shall preferably not be heated, or, if heated, shall be annealed. All steel castings shall be properly annealed. Material may be punched one-sixteenth inch (1/16•) larger than the nominal diameter of ·the rivets, whenever the thickness of the metal is e~ual to or less than the diameter of the rivets, plus one-eighth inch (1/8 11 ). !IJhen the metal is thicker than the diameter of the rivet, plus one-eighth inch (1/811 ), the holes shall be drilled, or sub-punched and reamed. Holes for shop turned bolts shall be sub-punched and reamed or drilled from the solid. Holes for field turned bolts shall be sub-punched in the shop and reamed in the field • . When sub-punching and reaming is required the die used for punching shall be one-sixteenth imrh (l/16 11 ) smaller than the nominal diameter of the rivet. n ivet holes{ after assembling, shall be reamed to a diameter one-sixteenth inch (1/1611 J greater than the nominal diameter of the rivet. Turned bolt holes, after assembling, shall be reamed (for field bolts in the field) to a diameter one-fifteenth inch (1/15") larger than the diameter of the turned bolt. Rivets are to be driven hot, and wherever pract±able, by power. Rivet heads shall be of hemispherical shape and uniform in size throughout the work for the same size rivet, full, neatly finished, and concentric with the holes. Rivets, after driving, shall be tight, completely filling the holes, and with heads in full contaat with the surface. Rivets shall be heated uniformly to a temperature not exceeding 1950° F. They shall not be driven after their temperature is below 1000° F. Loose, burned and otherwise defective rivets shall be replaced. Compression joints depending upon contact bearing shall have the bearing surfaces truly faced after the members are riveted. All other joints shall be cut or dressed true and straight. Finished members shall be true to line and free from twists, bends and open joints. Compression members may have a lateral variation not greater than 1/1000 of the axial length between points whioh are to be laterally supported. 0 _ .. . . - _ An allowable variation of one thirth-second inch (1/32•) is permissable in the overall length of members with both ends milled. Members without milled ends which are framed to other steel parts of the structure may have a variation from the detailed length not greater than one~ sixteenth inch (1/16 11 ) for members thirty feet (30 1 ) or less in length, and not greater than one-eighth inch (1/811 ) for members over thirty feet (30 1 ) in length. Planing or finishing of sheared plates or shapes will not be required un- less specifically called for on the drawings. All parts of riveted members shall be well pinned or bolted and rigidly held together while riveting. Drifting done during assembling shall not dis- tort the metal or enlarge the holes. Gas cutting may be done under the following conditions' 1. The contractor shall be required to satisfy the Building Inspector as to his ability to produce satisfactory gas cuts. 2. Gas cut edges shall be regular in contour. 3. Gas cutting may be used in the preparation of base metal parts for welding, provided the edges so cut are thoroughly cleaned after cutting so C as to expose clean metal. ' 0 4• Gas cutting shall not be permitted to replace the milling of surfaces specified elsewhere in this Code- 5. Gas cutting shall not be permitted on any member while it is carrying stress. To determine the net area of members so cut, one-eighth inch (1/811 ) shall be deducted from the gas cut edges. The radius of re-entrant &as cut fillets shall be as large as possible, but never less than one inch (111 ). Thia restriction shall not apply to detail cutting for the correction o! minor fabricating errors, where the removal of metal resulting from such gas cutting would not reduce the required strength of the member that is to be cut. 6l Gas cutting of holes in any member which has not been designed there· for shall not be permitted. Section 2723. Painting. Parts not in contact, but inaccessible after assembling, shall be properly protected by paint. All steel work, except where entirely encased in concrete, shall be thor- oughly cleaned and given one coat of approved metal protection well worked into .the joints and open spaces. Machine finished surfaces shall be protected against corrosion. Cast iron columns shall not be painted until after acceptance by the Build- ing Inspector. ' c 0 Section 2724. Erection. The frame of all steel skeleton buildings shall _be carried up true and plumb, and temporary bracing shall be introduced where- ever necessary to take care of all loads to which the structure may be sub- -jected, including erection equipment, and the operation of same. Such brac- ing shall be left in place as long as required for safety or deemed necessary by the Building Inspector. As erection progresses the work shall be securely bolted up to take care of all dead load, wind and erection stresses. Wherever piles of material, erection equipment, or other loads are carried duting erection, proper provision shall be made to take care of the resulting stresses. No riveting or welding shall be done until the structure has been proper- ly aligned. Rivets driven in the field shall be heated and driven \Vi th the same care as those driven in the shop. In the setting or erecting of steel work the individual pieces shall be considered plumb or level when the error does not exceed 1 to 500. For ex- terior columns and columna adjacent to elevator shafts of multiple stor.y, buildings the error shall not exceed 1 to 1000 of the total height of the column. Field painting shall be considered a phase of maintenance, not covered herein, and shall include spot painting of field rivet heads and all abra· sions of the shop coat, and so forth. The fact that the City of Lubbock has no adequate provision regulating light steel construction and immediate construction of ma~ buildings is con- templated in the absence of needed uniform provisions necessary to promote the public safety, creates an emergency requiring that this ordinance and amendment take effect from and after its passage, AND IT IS S.O ORDERED. Passed and approved first readiag this 24 day of January, 1946. Passed and approved second reading this ~ day of Ja~uary, 1946. Passed by unanirnJUS vote of all Commissioners and the Mayor. Attest#