1927 086 Ordinance - Laserfiche WebLink

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ment shall be spliced at such a point above the floor that the bond stress in the rod is developed enough to ca.riy the increased load transmitted to ito Seco7.38. CURTAIN WAI,I,S IN SKEI,ET'OI`z CDNSiRUCTIOIIT BUTLDIi1GS. Builclings having a complete skeleton eonstruction of steel or reinforeea concrete construc- tion, or a combination of both, may have exterior walls o f reinforced concrete 8 inches thi.clt, provid.ed, however, that such tiualls shall support only tneir own wbight and that such traalls shall have steel rein.forcement oz not less tnan three- tenths (.3) of 1 per cent in each directian vertically and horizon-tally, the rods spaced not inore than 12 inches centers and wired to e$.ch other at each intersection. All bars shall be l:apped for a length sufficient to develop their f'u_11 stress for the allowable anit stress fi'or adhesion. Additiional bars sha,ll be set around open- irgs, the verticals e!rired to the nearest horizontal ba-rs, and the h orizontal bars at top and bottom of openings shall be Evired to the nearest vertical bars. The steel rods shall be combined vrith the concrete and placed vahere the com bination vrill clevelop the greatest strength, and the rods shall be stagEered or placed a.nd secured so as to resist apressure oi 30 pounds per,sqo_ft. either from the exterior or from the int-erior on each and every square foot oi each wa11 panel. Sec.139. IMINI14+rTAF, THICICiiESS OF. SLABS. Reinforced concrete sil-all not be less tiian 4 inches for floors aild 3 inches ior roofs. Secvl40a FII3EPROOFING. For the purpose oi fire protection the outer sur- face of reiniorcing steel shall ae kept away from the suriace of the conerete. Two inches in colun-uzs and girders 1-i'T inches in beams. 3/4 inch in slabs: No reinforcing steel not protected from fire sha,ll be considered as add- ing to the strength of the construction. Lime or hard wall plaster shall not be considere(i as a fireproofin,o mater- ial in reinforced concre'tie taork. Sec.141. SYST174. No systein of reinforced concrete shall oe used wilicli is not capa'ule of design and investigation inaccorc.ance i=rith the fornn)la and princi- ples laid dovrn in this Codee Sec.142 e PROPORTIOiJ FOR ?,t?IXITvG RDiINFORCED CONCU± Ea All reini orced con- crete sha,ll be mixed in the proportion of one part Portland cemeilt to two parts clean sharp sand andnot more than iour parts aggregate. Itdhere sl,a.g or other similar material is used, the proportion of aggregate shall 'be reduced in order to have the vo3ds properlv filled. In no case•shall more than two parts sand be used to one part cernent ancl all mixing sha11 be done by machine except where limitcd quantities are required or where the condition oi the work na.kes nand mixi.ng preferable; hand 2nixing- to be done only when approved "oJ the Inspector of Buildings. In all rnixing the separate ingxedients shall be measured and shall be tlinro-a.ghlv mixed and must be una.form in color, appearance and consistency before plau.ing. Sec.143v CE11EN1, SAND AND TNERTS. (a) Cement. Only Port-land cement shall be used which conforms to the requirements and tests preseribed by Section 89 hereof. The minirnum requirements o= tensile ttrength for,briquettes one inch square in secti-on sha11 be Neat Cement.