EWPAA Structural Plywood and LVL Design Manual - Engineered ...

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12.11 Hypar Design - GeometryTo develop a hypar simply requires fixing the two opposite corners (a and c) of a rectangularor square plate and raising the other two corners (b and e) as shown in FIGURE 12.14(a).An interesting phenomena concerning the geometry of the hypar is that it is formed by astraight line moving over two other straight lines inclined to one another.A vertical plane penetrating the hypar parallel to the direction of the convex parabola willresult in the roof shape shown in FIGURE 12.14 (d).Vertical planes penetrating the hypar perpendicular to the directions of the diagonals ACand BD will expose convex and concave parabolas resulting in the saddle shape of FIGURE12.14(e).Horizontal planes, parallel to the dotted outline of FIGURE 12.15(a) penetrating the hypar, willexpose hyperbolas.With reference to the co-ordinate system (x,y,z) shown in FIGURE 12.15 (a),mathematically:When k = o the hypar degenerates to a plane surface.z = kxy (12.7)FIGURE 12.15: Two views of a single hyperbolic-paraboloid shell12.12 Hypar Design - Structural ActionStructurally the hypar consists of a system of intersecting arches and suspension cables,half the load being carried in tension by the suspension cables and half in compression bythe arches. Since sections taken parallel to both diagonals lead to the same parabola, the169
force at some point P (see FIGURE 12.15 (a)) on the edge, due to arch action, will be thesame as the force applied by the cable at that point. Also, because they act at equal anglesto the edge, but in opposite senses, there is no force component perpendicular to theedge member. Therefore, this double system of forces can be resolved into a series ofshear forces along the edge requiring a perimeter beam to carry them as shown in FIGURE12.15 (c).Since arching action is associated with compression forces, which in turn relates tobuckling, a limit must be placed on the ratio of the rise of the diagonal / span of thediagonal.Single shell support can be effected by providing suitable restraint at two support points,e.g. A & C in FIGURE 12.15 (a) being the most common. Accumulation of the membranalshears into the intersecting perimeter members at A & C results in larger thrusts having to beresisted at these two locations. This can be done by suitably designed buttresses or a tieacross AC which, although it is the most economical, detracts from appearance and reducesheadroom. Alternatively, the two high points (D & B) can be supported resulting in theperimeter members being in tension and the resultant force being inwards rather thanoutwards.12.13 Hypar Design - MethodologyThere are several methods available for determining the forces in a hypar shell the onefollowed herein is that presented in the Western Wood Products Technical Guide; HyperbolicParaboloid Shells.For symmetrical loading of the hypar shown in FIGURE 12.16 the vertical reactions (R) arehalf the sum of the vertical load (W). The horizontal thrust (H) can be determined byconsidering the triangle of base (/2), height (h) and hypotenuse (k). Since the total load(W) can be assumed to act vertically at (O) along the line of (h), and if the resultant of (H)and (R) is assumed to have its line of action (k), then summation of the moments of theforces to the left about (O) results in:Hence:M L ∑ 0 = 0= R. / 2 − HhR H=h / 2HR=2h(12.9)(12.8)Taking moments of the resultant force (F) and the vertical reaction (R) about (D) results in:R F=h k (12.10)Giving :Fk= Rh170
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Structural Plywood & LVL Design Man
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Table of Contents1 Plywood & LVL -
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11 Plywood Stressed Skin Panels ...
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Table of FiguresFIGURE 4.1: Plywood
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Part OneProduct Production & Proper
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PeelingAfter conditioning, the logs
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Sanding, Trimming and BrandingAfter
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through to applications where aesth
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2.7 Identification CodeThe plywood
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2.10 Non Structural PlywoodsInterio
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3.5 Veneer QualityVeneer quality us
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the hygroscopic movement of structu
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effective an insulator as the wood
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5 Structural Plywood - Design Princ
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12 - 13 40015 - 19 45020 - 25 52026
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TABLE 5.3: Standard Structural Plyw
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TABLE 5.5: Indicative Stiffness Val
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Strength Limit StateStrength LimitS
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Application of Structural memberAll
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FIGURE 5.5 shows an I-beam defining
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j 2- Duration of Load Factor for Cr
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Using the theory of parallel axes a
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6 Structural LVL - Design Principle
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I (neutral axis(NA)-stiffness= (bd
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Serviceability Limit State:Calculat
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Strength Limit State:Strength Limit
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Equilibrium Moisture Content (EMC)P
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(c) For shear k 11 = 1.0(d) For com
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Chapter 6 AppendixSlenderness Co-Ef
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FIGURE A6.3: Continuous restraint a
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Stability factor.The stability fact
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7.4 Structural Plywood Flooring - D
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5. Critical Load Action EffectsLoad
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5. Serviceability limit state - Des
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7.10 Structural Plywood Residential
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Because of the obvious difficulty a
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1.2 m roof load width)0.25 kPa x 1.
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Concentrated Imposed Load (Q)M max
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5. Serviceability Limit Stateand [A
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8 Structural Plywood Webbed Box Bea
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AdhesivesBeams relying only on an a
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5. Check Beam Stiffness:Check beam
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1. Initial beam trial size:(a)(b)Fr
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Required nail spacing s = øN j / q
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Figure 8.5 shows a discontinuous pl
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A8Chapter 8 AppendixBending / Compr
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where:A= h3.5 3D .1032 N. mJ12.440.
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FIGURE A8.2: Guide for Selecting In
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Table A8.6: Unit-Load Deflection Sp
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9 Structural Plywood Diaphragms & S
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FIGURE 9.3 shows a plywood panel na
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The following are the design steps
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Wind force, w on diaphragm w = 1.86
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Converted to Limit States CapacityC
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4. Chord Size and SplicesThe chords
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Load/Nail (N)Nail Deformation (mm)2
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• The horizontal force is 1.9 x 2
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= 5 kN/m v oR = 15/5 = 3 kN/m107
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ELEVATIONFIGURE 9.12: Shows shear f
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As previously mentioned the shearwa
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Assuming the applied racking load t
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In this instance let the two panels
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A9 CHAPTER 9 APPENDIXPlate 1Plate 2
Page 128 and 129: Plate 7Plate 8Plate 9119
Page 130 and 131: REFERENCES CITED:1. Timber Shearwal
Page 132 and 133: “nailability” by increasing res
Page 134 and 135: (a) (b) (c)FIGURE 10.3: Actual and
Page 136 and 137: Re-arranging the torsion equation r
Page 138 and 139: The polar moment of area (I p ) of
Page 140 and 141: Design Example - Plywood Gusseted P
Page 142 and 143: • assuming width of lines paralle
Page 144 and 145: hence:where:ΦMj⎡ Ip⎤= (0.8 x1.
Page 146 and 147: A10 Chapter 10 AppendixPhotographs
Page 148 and 149: MOMENT JOINTSPlate 7Plate 8Plate 9(
Page 150 and 151: REFERENCES CITED:1. Investigation o
Page 152 and 153: 11.2 MaterialsPlywoodPlywood used i
Page 154 and 155: FIGURE 11.3: Effective widths of pl
Page 156 and 157: Transformed SectionSince the plywoo
Page 158 and 159: FIGURE 11.5: Bending stresses in st
Page 160 and 161: FIGURE 11.6: Stressed skin panel tr
Page 162 and 163: Flexural Deflection Long Term Servi
Page 164 and 165: Compression SpliceUsing 17mm F11 st
Page 166 and 167: REFERENCES CITED:1. Design & Fabric
Page 168 and 169: 12 Exotic Structural Forms12.1 Intr
Page 170 and 171: displacement between diaphragms eac
Page 172 and 173: The section modulus (Z) is:ZZ=Iy1=1
Page 174 and 175: FIGURE 12.9: A parabolic arch (not
Page 176 and 177: F AFFFASS= (374.4 + 166.4)kN= 540.8
Page 180 and 181: FIGURE 12.16: Reactive force compon
Page 182 and 183: 12.14 Methodology - Principal Membr
Page 184 and 185: Many braced dome geometries exist b
Page 186 and 187: θasphere= is the angle subtended b
Page 188 and 189: AndNNNxyxyP=L21P=L12P=L33L2P3⎤+
Page 190 and 191: • whether or not to force the ply
Page 192 and 193: A12Chapter 12 AppendixEXAMPLES OF E
Page 194 and 195: EXOTIC STRUCTURAL FORMS DESIGN AIDS
Page 196 and 197: Type 1 joints referred to in AS 172
Page 198 and 199: FIGURE 13.3: Two and Three member T
Page 200 and 201: SECTION 4 : AS 1720.1-1997 : Clause
Page 202 and 203: connection load carrying capacity c
Page 204 and 205: 13.5 Design of Type 1 Nailed Connec
Page 206 and 207: The following unfactored loads are
Page 208 and 209: nnaa=nnr42=5= 9 rowsThe assumed val
Page 210 and 211: 13.11 Design of Type 2 Screwed Conn
Page 212 and 213: The reasons k 13 and k 14 are not c
Page 214 and 215: Type of JointSeasoned TimberUnseaso
Page 216 and 217: 13.16 Design of Type 2 Bolted Conne
Page 218 and 219: where:Δ = Δi +h33j14xh35Q *Qkpfor
Page 220 and 221: The exploded view in Figure 13.11 s
Page 222 and 223: FIGURE 13.12: Edge, end and bolt sp
Page 224 and 225: 13.21 Design of Type 2 Coach Screwe
Page 226 and 227: REFERENCES CITED:1. AS 1720.1-1997,
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Plate 3Plate 4219
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Plate 7Plate 8221
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14 Noise Control14.1 IntroductionTh
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The absorption process of a single
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When it is required to add more tha
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FIGURE 14.5: Types of cavity wallsT
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15 Condensation & Thermal Transmiss
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15.4 Thermal TransmissionThermal tr
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15.5 Thermal Transmission - Design
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REFERENCES CITED:1. Condensation, C
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The early fire hazard test indices
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ISO 9705 AND AS/NZS 3837These tests
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General InformationDesign of struct
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SpeciesAsh, Alpine - Eucalyptus del
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Results of recent tests organised b
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FlooringConstructionLVL(Substrates
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as expressed in the BCA.Species Ave
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ClosurePlywood Thickness for:Dougla
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Borers are rarely a problem with st
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HazardClassH1Exposure Specific serv
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17.3 Durability and Finishing Appli
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EWPAA MembersPlywood and Laminated
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