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ORDINANCE NO. NS ~518 <br />Page Seven <br /> <br /> TABLE D <br /> ALLOWABLE VALUE OF <br /> UNREINFORCED MASONRY WALL~I~ <br />WITH MINIMUM QUALITY MORTAR'-' <br /> <br />RATING <br />CLASSIFICATION <br /> <br /> MAXIMUM RATIO <br />UNSUPPORTED <br />HEIGHT OR LENGTH <br /> TO THICKNESS <br /> <br /> SEISMIC IN-PLANE <br />SHEAR STRESS <br />BASED ON GROSS AREA <br /> <br />I NOt applicable(2) Not applicable(2) <br />II 9 3 psi(3) <br />III 10 3 psi(3) <br />IV 12 3 psi(3) <br /> <br />FOOTNOTES: (1) Minimum quality mortar shall be determined <br />by laboratory testing in accordance with Section 8-2005 F. <br /> (2) Walls of buildings within rating classification I shall <br />be analyzed in accordance with Section 8-2005 F. (3) Allowable <br />shear stress may be increased by the addition of 10% of the <br />direct stress due to the weight of the wall directly above. <br /> <br />The wall height or length may be measured horizontally to <br />supporting elements providing the stiffness of the supporting <br />member is at least twice as stiff as the tributary wall. <br />Stiffness shall be based on the gross section. <br /> <br /> (2) EXISTING ROOF, FLOORS, WALLS, FOOTINGS, AND <br />WOOD FRAMING. Existing materials utilized in the described <br />configuration may be used as part of the lateral load resisting <br />system, provided that the stresses in these materials do not <br />exceed the values shown in Table E. <br /> <br /> TABLE E <br /> VALUES FOR EXISTING MATERIALS <br /> <br />MATERIALS(2) ALLOWABLE VALUES <br /> <br />HORIZONTAL DIAPHRAGMS <br /> <br />(a) Roofs with straight <br />sheathing and roofing <br />applied directly to the <br />sheathing. <br /> <br />150 lbs. per foot for <br />seismic shear. <br /> <br />(b) Roofs with diagonal <br />sheathing and roofing <br />applied directly to the <br />sheathing. <br /> <br />400 lbs. per foot for <br />seismic shear. <br /> <br />(c) Floors with straight <br />tongue and groove sheathing <br /> <br />150 lbs. per foot for <br />seismic shear. <br /> <br />(d) Floors with straight <br />sheathing and finished <br />wood flooring. <br /> <br />300 lbs. per foot for <br />seismic shear. <br /> <br />(e) Floors with diagonal <br />sheathing and finished <br />wood flooring. <br /> <br />400 lbs. per foot for <br />seismic shear. <br /> <br />(f) Floors or roofs with <br />straight sheathing and <br />plaster applied t~l~he <br />joist or rafters. <br /> <br />Add 50 lbs. per foot <br />to materials la and lc. <br /> <br /> <br />