2001 ASD Supplements - unprotected PDF - American Wood Council

ASD WOOD STRUCTURAL PANELS SUPPLEMENTSP-31where:where:w s= uniform load based on shear strength (psf)∆ = deflection (in.)F s(Ib/Q) = design shear strength capacity (lb.-in./ft.)w = uniform load (psf)l 2= clear span (in., center-to-center of supportsminus support width)EI = design bending stiffness capacity (lb.-in. 2 /ft.)l 3= clear span + SW (in.)Uniform Loads Based onDeflection RequirementsThe following formulas shall be used for computingdeflection under uniform load, or allowable loads basedon deflection requirements.For a single span:4wlD= 3921. 6 EΙSW = support width factor, equal to 0.25 inch for 2-inch nominal lumber framing and 0.625 inch for4-inch-nominal lumber framing. For additionalinformation on this factor see APA ResearchReport 120.For uniform load based on deflection requirements,compute bending deflection with a uniform load (w) equalto 1 psf. The allowable uniform load based on the allowabledeflection is then computed as:For a two-span condition:D=wl 342220 EΙwhere:w = d∆ all∆7For a three-span condition:D=wl 341743 EΙ7.2 Load-Span TablesThe following load-span tables apply to wood structuralpanels manufactured in accordance with one or moreof the standards listed in Section 2.1 and bearing the trademarkof a qualified inspection and testing agency. Loadsare provided for applications where the panel strength axisis applied perpendicular to supports and parallel to supports.For each combination of span and span rating, orspan and Group 1 sanded panel grade, loads are given fordeflections of L/360, L/240, L/180, and maximum loadcontrolled by bending and shear capacity.The values given in Tables 7.1 and 7.2 represent themaximum allowable loads without regard to panel type.These values may be adjusted for panel type using Table7.4, Adjustments to Allowable Load Capacities Based onPanel Grade and Construction. Once the allowable loadshave been adjusted for panel type, they should be furtheradjusted for application conditions using Table 7.5.w d∆ all= uniform load based on deflection requirement(psf)= allowable deflection (in.)∆ = computed deflection with a uniform load (w)equal to 1 psf, using either of the above threeformulas whichever is applicableNote: Spans shown in the tables may be in excess ofthe maximum recommended span (or span rating) for aspecific application, since other factors such as concentratedloads may be more critical than uniform load.Always check the maximum recommended floor and roofspans for wood structural panels before making a finalpanel selection for these applications.SUPPLEMENTAL DESIGN ASSISTANCEAPA – The Engineered Wood Association