1927 086 Ordinance - Laserfiche WebLink

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Notation 90d" is the effective depth or distande fror.i the compressive face to the center' of.the ste,el in inches. Sece131. SQUARTE AND F,.ECTANGULAR SLABS, For square slabs ztritYi two caay re- inforcements, the bending moment at the center of the slab -shall be not less °than 20. WT,2 for intermediate spans, and 18 WI,2 for the end spans. The moment eYer supporty shall be no-t less than 30 11FI,2 and the sum o f the moments over one support and at the center of the span sha11 be -talcen not less than 10 V'dL2 in which above Formula' "tiU" is the load per liileal foot and "Lr" the lergth of spana For square or rectangular slaus the distribution of the loads- in the twro directions, sha11 be inversely as the cubes oi the i;wo dimensionso Concrete beams and girders ynist be so- designed that the total comPressive stress to which:' the membex'may be subjected'will cornpare with the total stress taken by the steel reinforcementa Should the available area of section above the neutral axis be insufficients,the area, of seCtien of the member shall be in- creased or a sufficient amount-of compression steel be provided to insure an ef- ficient resisting moment. ' Seca132. TILE AND JOIST CONSTPUCTIONm 11l'nere reinforced concrete joist, with intermediate rovus of hollovr tile are erttployed, the stresses shall be cal.- culated by the,same fbrmulas provided for beams and girders. Secv133o Should the type of construction knovm as Flat'Slab, Ciraular Plate, Yushroom System, etce9 be employed the plans and specifications diall bear the signed approval of sorne recognized er_gineer of authority on the design of reinforced concrete constrizctiono Secalv4. REINFORCM) COPaCRE.'''iE COLU??I?TS. Reinforced concrete colwvns shall not exceed in length 15 times the least sid.e or diameter, and where such columns ea.ceed 12 titnes the least diamete'r or side, -tYle allowable conipression of the con- crete shall ae taken as 500 pounds multiplied by the least side or diameter of tlze coltiurm in inches and divided by the unsupported length in feeta For eolumns subjeet to eccentric loading or bending of an intermedia,te a- mount, the above stre9s shall be reduced at least 20 per cent. 171zen the bor_c%ing stresses in a column can be defir_itely determined, the combined be-n_ding and direct stress slzall not exeeed 500 pounds per sq. in. Colurnns erith lorigitudinal rods shall have at least 1 sq. in. of steel in the total axea., a.nd not less than 4 rods; and rods shall not be.used of a 1 ess diameter than z inch. The area.oi the longitudinal rods sha11 not be 1 ess than ? of one per eent (1 per cent)- of the required cross section,area of the columzz and shall not exceed 4 per cen-t oi the effective cross seeti,onal area of the co1- umn. The longitudinal rods must be-tied together to resist outcrard flext.lre at intiervals'not greater than'tne lea.st vridth or diameter of column. The steel hoops shall not be less than -L inch diameter 3n dEpaced not more than 12 incnes aparto B??( Sec.ke5. CONCRETL+'' COLUh?N F'OOTINGS., Plain Footingso The, area oi the 1ower cottrse of concreie footirk,s snall be governed by t11e available resistance of the ?soil upon which they are to oe placed. Single course footings shqll be not less than sixteen (16) tnches thick. LVhere more than one eourse is required- no course