Member Design - Timber Floor XX 20/08/2015 EC5 Ref Timber Material Properties

Transcription

1 Job No. Sheet No. E N G I N E E R S Consulting Engineers jxxx 1 Timber Material Properties Timber Name or Strength Class Mean Density, ρ mean 600kg/m 3 Material Safety Factor, γ m (1.30Solid; 1.25Glulam; 1.20LVL) 1.30 Service Class Permanent Medium Term k mod k def k mod k def Class Class Class Permanent Action - ULS Factored (DL+SDL) and SLS Unfactored (DL+SDL) Modification Factor for Temp, Moisture, Load Duration, k mod,pt 0.50 Modification Factor for Creep and Moisture, k def,pt 2.00 Medium Term Action - ULS Factored (DL+SDL+LL) Modification Factor for Temp, Moisture, Load Duration, k mod,mt 0.65 Modification Factor for Creep and Moisture, k def,mt 0.75 Factor for the Quasi-Permanent Value, ψ 2,mt 0.30 Medium Term Action - SLS Unfactored (DL+SDL+LL) For the (DL+SDL) component, the above permanent action values, whilst for the LL component, the above ULS medium term values. Geometry of Floor Joist Span, L (Usually m) 4.150m Joist LTB Length, L LTB = L /(1+Struttings) 2.075m Joist Buckling Length (h-plane), L euler,h = %.L 4.150m Joist Buckling Length (b-plane), L euler,b = %.L 0.830m Joist Spacing, s (Usually 400mm, 450mm or 600mm) 400 mm Bearing Length for Shear Force, l bearing (>=40mm) 50mm OK Precamber, u 0 0.0mm Section Properties Section Scheme and Number of Joist(s), NJ 1 Note NJ multiplies the dead load and divides the loading, ω; Joist Width, b 47 mm Joist Depth, h 200 mm Recommended depth based on span / depth = mm Recommended depth based on span in mm / mm Elastic Section Modulus, W (h-plane) = [1/12 b.h 3 ]/(h/2) 313cm 3 Depth h Modifier For Notched Sections, h mod% 80.0% Depth b Modifier For Notched Sections, b mod% (Usually 100.0%) 100.0% Note that all effects are for single joists. Double and triple joists are considered by NJ. Nothing else. Thus the multiple joists need not be fastenned together as their responses are considered to be independent. In reality, joists which are fastenned together at regular intervals would respond in between independent joists and a single joist of thickness the sum of the joists thicknesses;

2 Job No. Sheet No. E N G I N E E R S Consulting Engineers jxxx 2 Modification Factors Modification Factor for Bending Stress Redistribution, k m 0.7 Modification Factor for Bending Depth, k h 1.0 Solid Timber Glulam LVL where s 0.2 Modification Factor for System Strength (Load Sharing System), k sys 1.1 Modification Factor for Notched End Beams, k v 0.6 Distance, x 100mm Depth, h ef = h mod%.h 160 mm Angle, α 0.80radians Distance, i.(h-h ef ) 50 mm Angle, i 1.25 radians Modification Factor for Bearing, k c,90 (=1.0 Conservatively) 1.0

3 E N G I N E E R S Consulting Engineers Job No. Sheet No. jxxx 3 Member Design - Timber Floor Loading on Joist XX 20/08/2015 Live Load, LL (Including Partitions) (Usually 1.50kPa Domestic) Note dedicated beams supporting partitions should be specifically designed; Dead Load of Joist(s), NJ. ρ mean. g. b. h / s Super Dead Load of Carpet Finish Super Dead Load of Floor Finish Super Dead Load of Floorboards Thermal Insulation Super Dead Load of Services Super Dead Load of Ceiling DL + SDL SLS = DL + SDL + LL ULS = 1.4DL + 1.4SDL + 1.6LL 1.50 kpa 0.14kPa 0.03 kpa 0.03 kpa 0.11 kpa 0.03 kpa 0.00 kpa 0.11 kpa 0.45kPa 1.95kPa 3.03kPa ULS Permanent Loads (DL+SDL) udl, ω 1,ULS = (1.4DL+1.4SDL). S / NJ ULS Medium Term Loads (DL+SDL+LL) udl, ω 2,ULS = (1.4DL+1.4SDL+1.6LL) SLS Permanent Loads (DL+SDL) udl, ω 1 = (DL+SDL). S / NJ SLS Medium Term Loads (LL) udl, ω 2 = (LL). S / NJ 0.25kN/m 1.21kN/m 0.18kN/m 0.60kN/m Loading on Line Support Floor on One Side (F=1) or Both Sides (F=2) of Line Support, F Line LL UDL on Support = F. (LL in kpa). L/2 Line DL+SDL UDL on Support = F. (DL+SDL in kpa). L/2 3.11kN/m 0.93kN/m Utilisation Summary Perform Design ULS EC5 Design Perm Medium ULS Bending ( LTB) 19% 75% ULS Bending (+LTB) 21% 83% ULS Shear 15% 58% ULS Bearing 18% 70% Deflection Vibration 87% 97% Overall Utilisation 97% ULS Bending Stress 11% 40% (Note For Comparison Purposes Only)

4 Job No. Sheet No. E N G I N E E R S Consulting Engineers jxxx 4 ULS EC5 Capacity Approach and SLS Deflections and Vibrations Perform Design ULS EC5 Design Perm Medium Shear Force, V d kn Shear Utilisation 15% 58% Bearing Utilisation 18% 70% Bending Moment, M d knm Bending ( LTB) Utilisation 19% 75% Bending (+LTB) Utilisation 21% 83% Note shear force, V d = ωl/2; bending moment, M d = ωl 2 /8; SLS Permanent Loads (DL+SDL) udl, ω 1 SLS Medium Term Loads (LL) udl, ω 2 Precamber, u 0 Deflection Utilisation Vibration Utilisation 87% 97% 0.18kN/m 0.60kN/m 0.0mm ULS Stress Approach Note conservatively same strength criteria for axial and bending; However, since there is only bending action here, the bending design strength employed instead, hence equivalent to EC5 capacity approach; Note unconservatively no LTB; no Euler; no battened strut buckling; straight members; no Vierendeel; Note conservatively no k h, k sys and k c,90 ; Note unconservatively no k v ; Characteristic Strength in Bending, f m,k 42.04N/mm 2 Material Partial Safety Factor, γ m 1.30 Perm Medium Bending Stress, σ m,d = M d /W N/mm 2 Design Strength in Bending, f m,d = k mod.f m,k /γ m N/mm 2 Bending Stress Utilisation = σ m,d /f m,d 11% 40% ULS Connection Force Shear Force at Either End of Joist = MAX (V d,perm, V d,medium ) 2.5kN Notches and Openings in Joist Members

5 Job No. Sheet No. E N G I N E E R S Consulting Engineers jxxx 5 Job Title Scheme Design Member Design - Timber Floor EC5 v xlsm A typical domestic timber floor would consist bottom up of 12.5mm plasterboard, timber joists at 400mm centres(with restraint type joist hangers or 30x5mm galvanised mild steel straps at 2.0m max intervals for joists perpendicular to wall; with 30x5mm galvanised mild steel straps at 2.0m max intervals for joists parallel to wall), 21mm floor boards, 25mm thick resilient layer and timber flooring.

6 Job No. Sheet No. E N G I N E E R S Consulting Engineers jxxx 6

7 Job No. Sheet No. E N G I N E E R S Consulting Engineers jxxx 7 Job Title Member Design - Timber Floor EC5 v xlsm Member Design - Timber Floor XX 20/08/2015

8 Job No. Sheet No. E N G I N E E R S Consulting Engineers jxxx 8 Job Title Member Design - Timber Floor EC5 v xlsm Member Design - Timber Floor XX 20/08/2015

9 Job No. Sheet No. E N G I N E E R S Consulting Engineers jxxx 9 Member Design - Timber Floor Wall Lateral Restraint by Joist XX 20/08/2015 Lateral support is required to any external, compartment or separating wall longer than 3m at every floor, roof and wall junction. Lateral support is required to any internal load bearingwallofanylengthateveryfloorandroof.

10 E N G I N E E R S Consulting Engineers Job No. Sheet No. jxxx 10 Job Title Member Design - Timber Floor EC5 v xlsm Member Design - Timber Floor XX 20/08/2015

11 E N G I N E E R S Consulting Engineers Job No. Sheet No. jxxx 11 Wall Lateral Restraint by Perpendicular Joist (Bearing Connection) Joists that bear directly on the walls must not project into the cavity since this encourages fire spread and also subjects joists to moisture. Ends of joists should be treated with preservative againstpossibledecayduetomoisturepenetration.theremaybeasteelwallplate75x6mm to spread load of joists. The bricks are built around the joists and since the joists depth (notchedorotherwise)istobesmallerthanbrickdepth,thebrickdoesnotbearontothejoists. Max joist spacing 1.2m.

12 E N G I N E E R S Consulting Engineers jxxx 12 Wall Lateral Restraint by Perpendicular Joist (Joist Hanger) Galvanised pressed steel joist hangers can be employed as the wall is raised. This method does notexposeendofjoiststopossibledampnessandthereisnoneedforcuttingbrickorblockto fit around the joists. Wallstobestrappedatintervalsofnotmorethan2.0mwith30x5mmstraps.

13 E N G I N E E R S Consulting Engineers Job No. Sheet No. jxxx 13 Job Title Member Design - Timber Floor EC5 v xlsm Member Design - Timber Floor Wall Lateral Restraint by Perpendicular Joist (Restraint Type Joist Hanger) XX 20/08/2015 Joiststobeatnotmorethan1.2mcentresandrestrainttypejoistshangersemployedatnot more than 2.0m centres. Intermediate joist hangers need not be restraint type.

14 E N G I N E E R S Consulting Engineers jxxx 14

15 E N G I N E E R S Consulting Engineers jxxx 15 Wall Lateral Restraint by Parallel Joist

16 E N G I N E E R S Consulting Engineers Job No. Sheet No. jxxx 16 Lateral Torsional Buckling Restraint

17 E N G I N E E R S Consulting Engineers jxxx 17 Strutting is used to provide lateral torsional buckling restraint. Strutting is also used to maintain the timber joists in the vertical position. Also, new timber is often not as well seasonedasitshouldbeandasthetimbersdryouttheytendtoshrinkandloseshape(joists may twist) unless restrained with strutting. Strutting should be employed at supports and at certain intermediate span locations depending on the span.

18 E N G I N E E R S Consulting Engineers jxxx 18 Trimming Members

19 E N G I N E E R S Consulting Engineers jxxx 19 Floor Boards

20 E N G I N E E R S Consulting Engineers jxxx 20

21 E N G I N E E R S Consulting Engineers jxxx 21 Floor boards are laid across the floor joists and cramped together(along edges parallel to the span of the boards, i.e. perpendicular to span of joists) with the tongued and grooved (T&G) joints.theboards,astheyarecrampedup,arenailedtothejoistswithtwonailstoeachboard bearing on each joists. Thejointattheendofeachboardinitslengthiscalledtheheadingjoint.Theheadingjointsin floor boards should always be staggered in some regular manner. Obviously, the heading joint endsofboardsmustbecutsothattheendsofbothboardsmeetandrestonajoist(sincethe boards span between joists) to which the ends are nailed. Floor boards width: 65, 90, 113 or 137mm; Floor boards thickness (and max spans): 16 (505mm), 19(600mm), 21(635mm) or 28mm(790mm); Floor boards length: Up to 5m;

22 E N G I N E E R S Consulting Engineers jxxx 22

23 E N G I N E E R S Consulting Engineers jxxx 23

24 E N G I N E E R S Consulting Engineers jxxx 24

25 E N G I N E E R S Consulting Engineers jxxx 25

26 Cell References timber name/strength class 32 partial safety factor 1 Solid Timber Glulam LVL service class 3 Class 1 Class 2 Class 3 factor ψ 1 Domestic 0.3 Office 0.3 Congregation 0.6 Shopping 0.6 Storage 0.8 floorboards 7 None 0.00 Softwood Boarding 16mm 0.07 Softwood Boarding 19mm 0.08 Softwood Boarding 21mm 0.09 Plywood Boarding 9.5mm 0.06 Plywood Boarding 12.5mm 0.08 Plywood Boarding 18.0mm 0.11 Chipboard Boarding 19mm 0.15 Chipboard Boarding 22mm 0.17 Hardwood Boarding 25mm 0.16 Orientated Strand Boarding (OSB) YET Medium Density Fibre Boarding (MDF) YET carpet 1 Include 0.03 Exclude 0.00 one side or both sides 1 One Side 1 Both Sides 2 timber section 36 section scheme 1 Single Joist Double Joist Triple Joist strutting 2 Zero Strutting Single Strutting Double Strutting Triple Strutting ltb consideration 2 LTB Not Considered LTB Considered euler buckling length

27 E N G I N E E R S Consulting Engineers jxxx 26 Fire Resistance Plastered ceilings generally meet the requirement of controlling surface spread of fire. Any timber finish to the ceiling will need to be treated with a fire-retardant paint or varnish. Timber floors and supporting structure in dwelling houses of2or3storeysaretohaveafireresistanceperiodof30 minutes. This is met by, either (a) Floors of T&G, plywood, chipboard of 15mm thick, joists at least 37mm wide and a ceiling plasterboards of 12.5mm with 5mm neat gypsum plaster finish, or (b) Floors of T&G, plywood, chipboard of 21mm thick, joists at least 37mm wide and a ceiling plasterboards of 12.5mm with joints taped and filled.

28 E N G I N E E R S Consulting Engineers jxxx 27 Shrinkage Keep flooring materials dry during construction and do not fix flooring if moisture content of boarding or floor joists greater than 19%.

29 E N G I N E E R S Consulting Engineers jxxx 28 Job Title Double Floor Member Design - Timber Floor EC5 v xlsm Double floors are used when timber floor joists span extend beyond the economical spans. Steel normally used to break the span of the timber joists. To providefixing for the timber joists, timberplatesareboltedtothebottomflangeofthebeamandtheendsofthejoistsnotchedto fitandnailed.toprovideafixingforfloorboardstimberbearersarenailedtothesidesofjoists acrossthesupportingsteelbeam.whenthesteelbeamprojectsbelowtheceiling,itiscasedin plasterboard, which also acts as a fire protection.

30 E N G I N E E R S Consulting Engineers jxxx 29 Job Title Thermal Insulation Member Design - Timber Floor EC5 v xlsm Maximum U value for floors over unheated spaces such as a garage or the external environment(forcantileverfloors)is0.25w/m 2 K. L1:1995 Requirements L1:2002 Requirements

31 E N G I N E E R S Consulting Engineers jxxx 30

32 E N G I N E E R S Consulting Engineers Job No. Sheet No. jxxx 31 Member Design - Timber Floor Sound Insulation XX 20/08/2015

33 E N G I N E E R S Consulting Engineers jxxx 32 Pugging can be used to increase mass and hence reduce airborne sound. This involves spreadingalayerofplasterorsandonroughboardingfixedbetweenjoistsonbattensoron expanded metal lath and plaster. Pugging does not decrease impact sound. Impact sound can be reduced by laying carpet or some resilient material between the floorboards and joists, draped over the joists. Alternatively a floating floor, known as a platformfloorcanbeemployed.thisisa18mmthickt&gboardorchipboard(withalljoints glued)spotbondedtoabaseof19mmthickplasterboard,thenlaidona25mmthickresilient mineral fibre on a floor base of 12mm thick boarding or chipboard nailed to the joists. The ceiling comprises two layers of plasterboard, with joints staggered, to a finished thickness of 30mm on which 100mm of absorbent mineral fibre is laid. To limit flanking transmission of sound from the floor surface to the surrounding walls, a strip of resilient fibre material is fixed between the edges of platform, floors and surrounding solid wallsandagapof3mmisleftbetweentheskirtingandfloatingfloors.

34 E N G I N E E R S Consulting Engineers Job No. Sheet No. jxxx 33 Party Floor

35 E N G I N E E R S Consulting Engineers jxxx 34 Suspended Timber Ground Floor

36 E N G I N E E R S Consulting Engineers jxxx 35 A typical domestic suspended timber ground floor would consist bottom up of 150mm hardcore, 50mm blinding, 100mm concrete slab, honeycomb brick sleeper walls(such thatminimum150mmairspaceunderjoists)at1mcentres,bs743dpc,100x75timber wall plate, 100 x 50mm timber joists at 400 centres, 150mm mineral wool insulation with λ = W/mK between joists on plastic netting stapled to joists or 90mm rigid polyisocyanurate foam insulation with λ = W/mK between joists on chicken wire fixed to joists and 21mm timber floor boards. Ends of timber floor joists treated with preservative. Air bricks of 75x225mm in outer wall at 1m centres.

37 E N G I N E E R S Consulting Engineers jxxx 36 Sleeper walls are built m apart. Sleeper walls built 3 courses of brick high, up to sometimes 600mm high. Sleeper walls are built honeycombed to allow free circulation of air belowthefloor.theendsleeperwallisbuilt50mmfromtheinternalorexternalloadbearing walls and carries the end of the joists. This gap allows air to circulate. Under floor ventilation shouldhaveafreepathbetweenoppositesides,withopeningsequivalentto1500mm 2 foreach metrerunofwall. Concrete floor slab thickness for suspended timber ground floors for domestic purposes commonly 100mm. Alternatively, concrete floor slab thickness of 50mm on a DPM of 1200 gaugepolytheneonabedthatwillnotdamageit. Suspended timber floors require thermal insulation. Rolls or quilt of loosely felted glass fibre or mineralwoolcanbesupportedbyameshofplasticthatisdrapedoverthejoistsandstapledin position. Alternatively, semi-rigid slabs or batts of fibreglass or meneral wool can be supported betweenjoistsbynailsorbattensofwoodnailedtothesidesofthejoists. Air bricks of dimensions 215 x 65mm,215 x 140mm,or215 x 215mm.

38 E N G I N E E R S Consulting Engineers Job No. Sheet No. jxxx 37

39 E N G I N E E R S Consulting Engineers Job No. Sheet No. jxxx 38

40 E N G I N E E R S Consulting Engineers jxxx 39

41 E N G I N E E R S Consulting Engineers jxxx 40

42 E N G I N E E R S Consulting Engineers Job No. Sheet No. jxxx 41

43 E N G I N E E R S Consulting Engineers Job No. Sheet No. jxxx 42

44 E N G I N E E R S Consulting Engineers jxxx 43

45 E N G I N E E R S Consulting Engineers jxxx 44

46 E N G I N E E R S Consulting Engineers Job No. Sheet No. jxxx 45

47 E N G I N E E R S Consulting Engineers Job No. Sheet No. jxxx 46

48 E N G I N E E R S Consulting Engineers jxxx 47

49 E N G I N E E R S Consulting Engineers jxxx 48

50 E N G I N E E R S Consulting Engineers jxxx 49