Design Capacities for Structural Plywood

Transcription

1 Deign Capacitie for Structural Plyood Alloale Stre Deign (ASD) The deign value in thi document correpond ith thoe pulihed in the 005 edition of the AF&PA American Wood Council Alloale Stre Deign (ASD)/RFD Manual for Engineered Wood Contruction. TECO ha choen to do o to provide harmony among uer--architect, engineer, pecifier and the regulatory community. Thee are Indutry Recommended value, ut are not rigorouly evaluated for on-going verification. oad capacitie, hich are preented here for alloale tre deign (ASD) (Tale A), are applicale to plyood panel qualified in accordance ith TECO tet protocol. Nominal panel thickne (Tale B) ait in calculation of geometric cro-ectional propertie. The applicale ection propertie (Tale C) can e divided into load capacity to determine deign trength and tiffne. oad capacitie in Tale A are aed on normal duration of load for untreated panel under dry condition. Becaue thee value are plyood-pecific, the appropriate panel grade and contruction adjutment factor, C G, have already een applied. Deigner mut e careful to avoid making the C G adjutment again. Adjutment factor for other condition are permitted in accordance ith applicale code proviion. The National Deign Specification for Wood Contruction (NDS) provide guidance on the ue of adjutment factor. General Deign Information Method preented in thi ection may e ued to calculate uniform load capacity of tructural-ue panel in floor, roof and all application. The deign capacitie preented in Tale A include the grade and contruction factor, C G. Other applicale adjutment factor a pecified in Section 9.3 of the 005 edition of the ANSI/AF&PA NDS-005, National Deign Specification (NDS) for Wood Contruction ASD/RFD and Section C9.3 of the 005 Edition of the AF&PA American Wood Council Commentary National Deign Specification (NDS) for Wood Contruction ASD/RFD, hould e applied to the deign capacitie. There are three poile pan condition to conider hen computing the uniform load capacitie of tructural-ue panel depending on the ize and orientation of the panel and the pacing of the framing upport memer. Thee include ingle-pan, to-pan and three-pan (ee elo). For normal framing practice and tandard panel ize (i.e., x8 foot), hen the panel trength axi i perpendicular to framing upport, the three-pan condition i ued for upport pacing up to and including 3 inche on center. Ue the to-pan condition for upport pacing greater than 3 inche on center ut no greater than 8 inche on center. When the panel trength axi i placed parallel to framing upport, the three-pan condition i ued for upport pacing up to and including 16 inche on center. Ue the to-pan condition for upport pacing greater than 16 inche ut no greater than inche on center. Ue the ingle-pan condition for upport pacing greater than inche on center. The formula preented are for computing uniform load on tructural-ue panel applied over conventional framing. Thee equation are aed on tandard eam formula altered to accept the mixed unit. For upport pacing le than 8 inche, nominal to-inch framing memer are aumed. For upport pacing 8 inche and greater, nominal fourinch framing memer are aumed. Since the formula aume that no locking i ued, the formula are for one-ay "eam" action rather than to-ay "plate" action. The reulting load are for the tructural panel only and do not account for the deign of the framing upport memer. The reulting load calculated from the equation are aumed to apply to full ize panel in tandard heathing application. Conideration for concentrated load hould e made in compliance ith local uilding code and maximum pan recommendation. Page 1 of 7 V1.0 01/008

2 Tale A Wood Structural Panel Deign Capacitie Baed on Span Rating (a) Strength Planar Shear Stiffne and Rigidity Span Rating Bending F S (l-in/ft of idth) Axial Tenion F t A (l/ft of idth) Axial Compreion F c A (l/ft of idth) Shear through the thickne (,c) F v t v (l/in of hearreiting panel length) Planar Shear F (I/Q) (l/ft of idth) Capacitie relative to trength axi (d) Bending EI (l-in /ft of idth) Axial EA (l/ft of idth x 10 6 ) Rigidity through the thickne G v t v (l/in of panel depth) / / 90 Sheathing Span /0 3/16 0/0 8/ 3-ply 3-ply -ply 3-ply -ply -ply , ,300,800,800 3,60,900,900 3,770,000 5, ,50 1,50 1,65 1,600 1,600,080 1,950,535,850 3,550 5,35 5,35,00,500 3,100,650,650,000 7,00 7, ,500 16,500 16,500 0,000 0,000 3,600 8,100 17,80 5,110 18,000 39,600 55,800 6,900 91, ,000 7,000 35,100 0,500 8,500 37,050,750 0,300 6,500 Floor Span 0 oc oc 3 oc 8 oc -ply -ply ,0 1, ,,900 3,770 3,350,355 5,00 7,80 1,600,080 1,950,535 3,50,75 9,50 1,150 7,00 7,00 9,300 10, ,000 31, , , ,000 1,65,000 8,600 0,300 57,00 80,600 3, ,00,000 39,000 5,000 5,000 75,750 (a) () (c) (d) The deign value in thi tale correpond ith thoe pulihed in the 005 edition of the AF&PA American Wood Council Alloale Stre Deign (ASD)/RFD Manual for Engineered Wood Contruction Tale M9..1- M9.., hich are availale from the AF&PA American Wood Council. The appropriate panel grade and contruction adjutment factor, C G, ha already een incorporated into thee deign value do not apply the C G factor a econd time. Thee value do not apply to Structural I panel. See Tale M9..1 M9.. for the appropriate multiplier for Structural I panel. Shear through the thickne deign capacitie are limited to ection to feet or le in idth; ider ection may require further reduction. applie to plyood ith 5 or more layer; for /3-layer plyood, ue value for -ply plyood. Strength axi i defined a the axi parallel to the face and ack orientation of the grain (veneer), hich i generally the long panel direction, unle otherie marked. Page of 7 V1.0 01/008

3 Tale B Relationhip Beteen Span Rating and Nominal Thickne for Plyood (a) Span Rating Nominal Thickne () 3/8 7/16 15/3 1/ 19/3 5/8 3/3 3/ 7/ /8 / / Sheathing Span 3/ (in.) 0/ / Floor Span 16 oc oc oc oc oc 1.15 (a) The value in thi tale correpond ith thoe pulihed in the 005 edition of the AF&PA American Wood Council Commentary National Deign Specification (NDS) for Wood Contruction ASD/RFD Tale C9..3, hich i availale from the AF&PA American Wood Council. () The predominant thickne for each pan rating i highlighted in old. Tale C Panel Section Propertie (a,) for Plyood Cro Shear Nominal Thickne, t Weight (c) Moment of Section Statical Sectional Contant, (in.) Inertia, I Modulu, S Moment, Q (pf) Area, A Fraction Decimal (in. (in. /ft) (in. 3 /ft) (in. 3 I/Q /ft) /ft) (in. /ft) 3/ / / ½ / / / ¾ / / (a) () (c) The value in thi tale correpond ith thoe pulihed in the 005 edition of the AF&PA American Wood Council Commentary National Deign Specification (NDS) for Wood Contruction ASD/RFD Tale C9.., hich i availale from the AF&PA American Wood Council. Baed on a rectangular cro ectional idth of one foot. Weight i aed on an aumed panel denity of 36 pcf. Page 3 of 7 V1.0 01/008

4 Uniform oad Baed on Bending Uniform oad Formula for Structural-Ue Panel 1 The folloing formula may e ued to calculate load aed on deign ending (M): Single pan: To-pan condition: Three-pan condition: 96 M 96 M 10 M here: M uniform load aed on ending trength (pf) Bending Strength Capacity, F S in (l.-in./ft.) pan (center-to-center of upport, in.) Uniform oad Baed on Shear The folloing formula may e ued to calculate uniform load aed on planar hear (V ): Single pan: To-pan condition: Three-pan condition: V here: ( 19.) V 0 V V uniform load aed on hear trength (pf) Planar Shear Capacity, F (IB/Q) in (l./ft.) clear pan (in., center-to-center of upport minu upport idth, in.) Page of 7 V1.0 01/008

5 Uniform oad Baed on Deflection Requirement The folloing formula may e ued to calculate deflection under uniform load, or alloale load aed on deflection requirement. Single pan: To-pan condition: Three-pan condition: ( 91.6)EI ( 0)EI ( 173)EI here: deflection (in.) uniform live load (pf) Or T uniform total load (pf) EI Bending Stiffne Capacity (l.-in. /ft.) clear pan + SW (in.) SW upport idth factor, 0.5 inch for to-inch nominal lumer framing and 0.65 inch for fourinch nominal lumer framing. 1 The formula are tandard eam formula adjuted to accept mixed unit. It i aumed the reulting load are applied on all pan to full-ized panel in tandard heathing application. Refer to the 005 edition of the ANSI/AF&PA NDS- 005, National Deign Specification (NDS) for Wood Contruction ASD/RFD, for further requirement regarding the ue of thee formula and appropriate adjutment factor availale from the AF&PA American Wood Council. Page 5 of 7 V1.0 01/008

6 Plyood Roof Deign Example Calculation Uing ASD x8 foot, 3/16, -ply, TECO SHEATHING SPAN plyood panel are intalled a roof heathing over roof true (nominal inch ide) paced at 3 inche on-center. The panel are intalled ith the long panel direction (trength axi) perpendicular to the roof tru memer. The jo pecification indicate that the roof i to e deigned to upport a 0 pf no 1.15 load duration ith an alloale live load deflection ( ) of pan/0 and an alloale total load deflection ( T ) of pan/180. Determine if the pecified panel ill adequately meet thee requirement. Bending Strength From Tale A, the F S (ending capacity) of a 3/16, -ply SHEATHING SPAN panel intalled ith the tre applied parallel to the trength axi i equal to 07 l-in/ft of idth. The C G factor (panel grade and contruction factor) ha already een applied to thi capacity, ut the load duration factor, C D, of 1.15 can alo e applied for no load. Since the true are paced at 3 in. on center and the panel are oriented ith their 8 ft dimenion perpendicular to the framing, ue the equation for the three-pan condition. 10 F S 10 (07 l - in/ft) (1.15) (3 in) 55 pf Shear in the Plane Strength From Tale A, the F (I/Q), planar hear capacity, of a 3/16, -ply SHEATHING SPAN panel intalled ith the tre applied parallel to the trength axi i equal to 198 l/ft of idth. The C G factor (panel grade and contruction factor) ha already een applied to thi capacity, ut the load duration factor, C D, of 1.15 can alo e applied for no load. 0 F (I/Q) 0 (198 l/ft) (1.15) (3 in -1.5 in) 19 pf Page 6 of 7 V1.0 01/008

7 Bending Stiffne From Tale A, the EI (ending tiffne capacity) of a 3/16, -ply SHEATHING SPAN panel intalled ith the tre applied parallel to the trength axi i equal to 16,500 l-in /ft of idth. The C G factor (panel grade and contruction factor) ha already een applied to thi capacity. Notice that the load duration factor, C D doe not apply to ending tiffne. ( 173) ( 173) ( 173) 33 pf EI EI here (16,500 l -in (3 in -1.5 in +.5 in) /0 /ft) (3/0) T T T T T ( 173) ( 173) ( 173) pf EI EI T here (16,500 l -in (3 in -1.5 in +.5 in) T pan/180 /ft) (3/180) Baed on the pecification for thi deign example, the deign capacity of the 3/16, -ply SHEATHING SPAN plyood panel i controlled y ending tiffne. The pf repreent the maximum uniform load that can e applied to the panel efore the deflection criterion of pan/180 i exceeded. A long a the dead load of the roof ytem (i.e., eight of panel, hingle, etc.) doe not exceed pf (i.e. pf total load 0 pf no load), the 3/16, -ply SHEATHING SPAN plyood ill meet the deign pecification for thi project. Page 7 of 7 V1.0 01/008