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TIMBER FRAMINGUSING AS 1684.2 SPAN TABLES
AS 1684 Teaching Guide
AS 1684-2010 Residential timber-framed construction
• Go to www.education.WoodSolutions.com.au for up to date teaching resources including an annotated copy of the standard.
• This powerpoint presentation is part of a series that has been revised to reflect the requirements of AS 1684 Parts 2 & 3 – 2010 Edition.
• Some major changes to this edition include amendments to wall nogging requirements, inclusion of ring beam systems and an Appendix of building practices for engineered wood products (EWPs).
• The MGP span tables provided with the Standard have also been amended.
AS 1684-2010 Residential timber-framed construction
the timber framing standardAS 1684RESIDENTIAL TIMBER-FRAMED CONSTRUCTION
Currently you should be using the 2010 Edition.
Provides the building industry with procedures that can be used to determine building practice to design or check Construction details, determine member sizes and bracing and fixing requirements for timber framed construction in Non-Cyclonic areas (N1 – N4).
AS 1684TIMBER-FRAMING STANDARD
AS 1684.2 – CD Span Tables
Contains a CD of Span Tables (45 sets in all) for wind zones N1 - N4 for the following timber stress grades:Unseasoned Softwood:F5, F7Seasoned Softwood:F5, F7, F8MGP10, MGP12, MGP15Unseasoned Hardwood:F8, F11, F14, F17Seasoned Hardwood:F14, F17, F27
AS 1684TIMBER-FRAMING STANDARD
Each set of Span Tables contains 53 separate design tables
AS 1684TIMBER-FRAMING STANDARD
Using AS 1684 you should be able to design or check virtually every member in a building constructed using timber framing.
AS 1684TIMBER-FRAMING STANDARD
BearersStumps or piles
Floor joists
Battens
Roofing
Ridge beam
Ceiling
Flooring
Ceiling battens
Floor joists
Lintel
Wall frame Wall stud
FlooringInternal cladding
External cladding
Ceiling battens
First floor wall frames
Hanging beamsRafters
AS 1684TIMBER-FRAMED CONSTRUCTION
WHERE CAN AS1684 BE USED?
AS 1684Scope and Limitations
Plan: Rectangular, square or “L”-shapedStoreys: Single and two storey constructionPitch: 35o max. roof pitchWidth: 16m max. (between the “pitching points” of the roof, i.e. excluding eaves)
16.0 m max.W
16.0
m m
ax.
W
16.0 m maxW
AS 1684Physical Limitations -
Width
16.0 m max.
Pitching Point of main roof.
P itching Point of garage roof.
P itching Point of verandah orpatio roof.
P itching Point of main roof.
16.0 m max. 16.0 m max.
Main houseGarage Verandahor Patio
AS 1684Physical Limitations - Width
The geometric limits of the span tables often will limit these widths.
Wall Height
The maximum wall height shall be 3000 mm (floor to ceiling) as measured at common external walls (i.e. not gable or skillion ends).
AS 1684Physical Limitations – Wall Height
Design Forces on Buildings
LIVE LOADS (people, furniture etc.)
DEAD LOAD (structure)
Construction loads (people, materials)
DEAD LOAD (structure)
Suction
Internal pressure
Suction (uplift)
Wind
(a) Gravity loads (b) Wind loads
AS1684 can be used to design for Gravity Loads (dead & live) and wind loads.
AS 1684Physical Limitations – Design Forces on Buildings
Wind Classification
Non-Cyclonic Regions A & B only
N1 - W28N 100km/h gust
N2 - W33N 120km/h gust
N3 - W41N 150km/h gust
N4 - W50N 180km/h gust
AS 1684Wind Classification
Wind Classification
Wind Classification is dependent on :
Building height
Geographic (or wind) region (A for Victoria)
Terrain category (roughness of terrain)
Shielding classification (effect of surrounding objects)
Topographic classification (effect of hills, ridges, etc.)
AS 1684Wind Classification
AS 1684Wind Classification – Simple References
Geographic Region A
Site Location Top ⅓ of hill or ridge
Below top ⅓ of hill or ridge
Suburban siteNot within two rows of:•City or Town perimeter (as estimated 5 years hence)•Open areas larger than 250,000 m2
N2 N1
Less than 250m from:•the sea •open water wider than 250m
N3 N2Within two rows of:•City or Town perimeter (as estimated 5 years hence)•Open areas larger than 250,000 m2
Rural areas
Design fundamentals & basic terminology
Roof framing
Wall framing
Floor framing
(Click on arrow to move to section required)
AS 1684Using Span Tables
DESIGN FUNDAMENTALS
&
BASIC TERMINOLOGY
AS 1684Using Span Tables
Design FundamentalsAS 1684 SPAN TABLESDesign Fundamentals – Load Path
You build from the Bottom up.
But you design from the Roof down because loads from above can impact on members below.
So start with the roof and work down to the ground level.
Understanding the concept of a ‘load path’ is critical. Loads need to be supported down the building to the ground.
Indirect Load path due to cantilever
Roof
Load
Ground level
AS 1684 SPAN TABLESDesign Fundamentals – Load Path
Indirect Load path due to cantilever
Roof
Load
Ground level
AS 1684 SPAN TABLESDesign Fundamentals – Load Path
It is possible to decrease timber member size when:Sharing loads across many members.Using members with higher stress grades.
As a general rule it is necessary to increase the timber member size when:Load increases (a function of dead, live, wind loads).Span increases (a function of load paths across openings).Indirect load paths occur (e.g. cantilevers and offsets).
Loads are distributed equally between Points of Support.
Of the total load on Member X one half (2000 mm) will be supported by the beam or wall at “A” and the other half (2000 mm) will be supported by the beam orwall at “B”.
BA
MEMBER X
Loads distributedAS 1684 SPAN TABLESDesign Fundamentals – Load Distribution
Beam A will carry 1000 mm of loadBeam B will carry 3000 mm(1000 mm plus 2000 mm on other side)Beam C will carry 2000 mm
If Member X is supported at three or more points it is assumed that half the load carried by the spans either side of supports will be distributed equally.
A B C
MEMBER X
AS 1684 SPAN TABLESDesign Fundamentals – Load Distribution
A B C
Terminology - Span and SpacingAS 1684 SPAN TABLESTerminology – Span
Span is the “face-to-face” distance between points capable of giving full support to structural members or assemblies.
Joist Span (between internal faces of these support members).
Bearers and Floor Joists
S i n g l e s p a n
S i n g le s p a n S i n g le s p a n
S a w c u t J o in t o r l a p
AS 1684 SPAN TABLESTerminology – Single Span
The span of a member supported at or near both ends with no immediate supports.
This includes the case where members are partially cut through over intermediate supports to remove spring.
The term applied to members supported at or near both ends and at one or more intermediate points such that no span is greater than twice another.
C o n t i n u o u s s p a n
C o n t i n u o u s s p a n
NOTE: The design span is the average span unless one span is more than 10% longer than another in which case the design span is the longest span.
AS 1684 SPAN TABLESTerminology – Continuous Span
Span 2 is not to be greater than twice Span 1.This span is used to determine the size using the Continuous Span tables.
Span 1 (2000 mm) Span 2 (3925 mm)
1/3 (2000 mm)
The center support must be wholly within
the middle third.
6000 mm
1/3 (2000 mm) 1/3 (2000 mm)
75 mm 75 mm 75 mm
Example: Continuous SpanAS 1684 SPAN TABLESContinuous Span Example
Rafter
Terminology – Rafter Span and Overhang
Rafter spans are measured as the distance between points of support along the length of the rafter and NOT as the horizontal projection of this distance.
AS 1684 SPAN TABLESTerminology - Rafter Span and Overhang
Terminology - Span and Spacing
Bearers and Floor joists
AS 1684 SPAN TABLESDesign Fundamentals – Spacing
Spacing is the centre-to-centre distance between structural members unless indicated otherwise.
Joist Spacing(Centreline-to-Centreline)
Bearer Spacing(Centreline-to-Centreline).
Loadbearing wallA wall that supports roof loads, floor loads or both.
Non-Loadbearing internal wallA wall that does not support roof or floor loads but may support ceiling loads and act as a bracing wall.The main consideration for a non-loadbearing internal wall is its stiffness (i.e. resistance to movement from someone leaning on the wall, doors slamming shut etc.).
Terminology – Wall ConstructionAS 1684 SPAN TABLESTerminology – Wall Construction
Ridge board
Rafters & Ceilin g Jo ist m ust befixed to geth er a t the p itch in g po in ts
Ceiling jo is t
Rafte r
o therw ise there is no th in g to stopth e w alls fro m spreading
and th e ro of fro m collapsing
Ceiling jo is t(C olla r Tie )
Rafte r
R idge board
T his m eth o d of roo f co nstru ctio n is n o t covered by A S1684
Terminology – Roof Construction
Coupled Roof - rafters are tied together by ceiling joists so that they cannot spread.
AS 1684 SPAN TABLESTerminology – Roof Construction
Non-coupled roof - a pitched roof that is not a coupled roof. It includes cathedral roofs and roofs constructed using ridge and intermediate beams
R id g e B e a m
R a fte r In te rm e d ia te B e a m
Such roofs rely on ridge and intermediate beams to support the centre of the roof. These ridge and intermediate beams are supported by walls and/or posts at either end.
AS 1684 SPAN TABLESTerminology – Roof Construction
ROOF FRAMING
AS 1684 SPAN TABLESUsing Span Tables
The “footprint” of a building generally consists of a rectangular block or multiple blocks joined together. Roof shapes are made to cover the footprint while also providing sloping planes able to shed water.
HipSkillion
Gable (Cathedral or flat ceiling)
Dutch Hip (or Dutch Gable)
Hip and valley
AS 1684 SPAN TABLESRoof Framing – Typical Basic Roof Shapes
R i d g e b o a rd
C o l la r t ie
U n d e r p u r l in
S t ru tS t ru t t i n g b e a m
C e i l i n g jo i s tS t r u t
R a f te r
To p p l a te To p p l a te
AS 1684 SPAN TABLESRoof Framing – Typical Members
3. Rafters – take batten loads and transfers them to the support structure below e.g. walls.
Support wall
AS 1684 SPAN TABLESRoof Framing - Transferring loads to Pitched Roof
1. Roofing material - takes live/dead/wind loads and transfers them to the Battens.
2. Battens - takes roofing loads and transfers them to the Rafters/Trusses.
Typical ProcessStep 1: Determine the wind classification to factor in wind loads (e.g. assume non-cyclonic winds N1 or N2)Step 2: Determine type of roof (e.g. tiled or sheet.)Step 3: Determine batten spacing – typically 330 mm for tiles, or 450, 600, 900, 1200 mm sheet Step 4: Determine batten span – this will be the supporting rafter spacing. Batten
Span
Batten
Spacing
AS 1684 SPAN TABLESRoof Framing – Batten Design
AS 1684 SPAN TABLESRoof Framing – Batten Design
Step 7: Select column in the table for the previous batten “spacing and span” assumptions.
Step 5: Look up relevant Batten Span Table (i.e. non-cyclonic winds N1 and N2) in AS1684 Vol. 2.Step 6: Choose a table reflecting preferred stress grade.
AS 1684 SPAN TABLESRoof Framing – Batten Size Example
Inputs required Wind Classification = N2 Timber Stress Grade = F8 Roof Type = Steel Sheet (20 kg/m2) Batten Spacing = 900 mm Batten Span = 900 mm
AS 1684 SPAN TABLESRoof Framing – Batten Size Example
Batten Span = 900 mm
Wind Classification N2
Timber Stress Grade F8
Roof Type - Steel Sheet (20 kg/m2)
Batten Spacing = 900 mmA 38 x 75 mm F8 Batten Is adequate
Simplify
table
2006
Step 1: Determine the wind classification to factor in wind loads. For this example assume non-cyclonic winds N1 or N2.
Step 2: Determine dead/live loads on rafters . For this example assume loads are as for a tiled roof with battens (e.g. 60kgs/m2)
Step 3: Determine the rafter span. For the example assume a 2100 mm single rafter span.
Step 4: Determine the rafter overhang which creates a cantilever span adding extra load. For the example assume a 500 mm overhang.
Step 5: Determine the rafter spacing as this determines how much roof loads are shared between rafters. For the example assume a 600 mm spacing .
Ridge beam
Overhang
Rafter span
RafterSpacing
AS 1684 SPAN TABLESRafter Design - Cathedral Roof Scenario
Step 6 Look up AS1684 Vol 2
Step 11 Read off rafter size – 90x45mm
Step 7 Choose table reflecting preferred stress grade
Step 8 Determine which column in table to select using the previous “rafter spacing” and “single span” assumptions.
Step 9 Go down the column until reaching assumed 2100 mm rafter span and 500 mm overhang
Step 10 Check the spans work with assumed roof load of 60kgs/m2
AS 1684 SPAN TABLESRafter Design - Cathedral Roof Scenario
AS 1684 SPAN TABLESRafter Design - Cathedral Roof Scenario
Inputs required Wind Classification = N2 Stress Grade = F8 Rafter Spacing = 900 mm Rafter Span = 2200 mm Single or Continuous Span = Single Roof Mass (Sheet or Tile) = Steel Sheet (20 kg/m2)
Simplify table
Inputs required• Wind Classification = N2• Stress Grade = F8• Single or Continuous Span = Single• Rafter Spacing = 900 mm• Rafter Span = 2200 mm• Roof Mass (Sheet or Tile) = Steel Sheet
(20 kg/m2)
Inputs required• Wind Classification = N2• Stress Grade = F8• Single or Continuous Span = Single• Rafter Spacing = 900 mm• Rafter Span = 2200 mm• Roof Mass (Sheet or Tile) = Steel Sheet
(20 kg/m2)
A 100 x 50mm F8 rafter
is adequate
Maximum Rafter or Purlin Span & Overhang (mm)
At least 2200mm
2006
Determine Rafter Size
Ceiling Joist Design
Design variables• Timber Stress Grade• Ceiling Joist Spacing• Ceiling Joist Span• Single or Continuous Span
Ridge board
Ceiling Joist
Rafter
AS 1684 SPAN TABLESCeiling Joist Design
Ceiling Joist DesignAS 1684 SPAN TABLESCeiling Joist Design Example
Inputs required Wind Classification = N2 Stress Grade = F17 Overbatten = No Single or Continuous Span = Single Joist Spacing = 450 mm Ceiling Joist Span = 3600 mm
Ceiling Joist Size
Inputs required• Wind Classification = N2• Stress Grade = F17• Overbatten = No• Single or Continuous Span = Single• Joist Spacing = 450 mm• Ceiling Joist Span =
3600mm
Inputs required• Wind Classification = N2• Stress Grade = F17• Overbatten = No• Single or Continuous Span = Single• Joist Spacing = 450 mm• Ceiling Joist Span =
3600mm
Simplify table
A 120 x 45mm F17
ceiling joist is adequate
At least 3600mm
2006
Some members do not have to be designed using span tables. They are simply called up or calculated based on members framing into them.
Member Application Minimum size (mm)
Unstrutted ridge in coupled roof Depth not less than length of the rafter
plumb cut 19 thick
Strutted ridge in coupled roof with strut spacing not greater than 1800 mm
Depth not less than length of the rafter plumb cut 19 thick
Ridgeboards
Strutted ridge in coupled roof with strut spacing greater than 1800 to 2300 mm
Depth not less than length of the rafter plumb cut 35 thick
Stress grade F11/MGP15 minimum and no less than rafter stress grade
50 greater in depth than rafters 19 thick (seasoned) or 25 thick
(unseasoned) Hip rafters
Stress grades less than F11/MGP15 50 greater in depth than rafters min. thickness as for rafters
Valley rafters Minimum stress grade, as for rafters 50 greater in depth than rafters
with thickness as for rafter (min. 35)
Valley boards See Note 19 min. thick width to support valley gutter
Struts to 1500 mm long for all stress grades 90 45 or 70 70
Roof struts (sheet roof) Struts 1500 to 2400 mm long for all
stress grades 70 70
Ridge boardAS 1684 Span TablesOther Members And Components - Ridge board
The loads from roof members often impact on the design of members lower down in the structure.This impact can be determined from the following load sharing calculations:Roof Load Width (RLW).Ceiling Load Width (CLW).Roof area supported.
AS 1684 Span TablesRoof Member Load Impacts
AS 1684 Span TablesRoof Member Load Impacts – Roof Load Width
RLW is the width of roof that contributes roof load to a supporting member. It is used as an input to Span Tables for:Floor bearers.Wall studs.Lintels.Ridge or intermediate beams.Verandah beams.Roof Load Widths are measured onthe rake of the roof. A
B
3000
15001500
AS 1684 Span TablesRoof Member Load Impacts – Roof Load Width
ayx
2
RLW wall A = byx
2
RLW wall B =
x ya b
A B
The roof loads on trusses a re d is tr ibu ted equally betw een w a lls 'A ' and 'B '.
AS 1684 Span TablesRoof Member Load Impacts – With Trusses
ax
2RLW wall A = b
y
2RLW wall B =
R LW R LW
R LW
213
x ya b
RLW RLW
A B
**
AS 1684 Span TablesRoof Member Load Impacts – Without Ridge Struts
For a pitched roof without ridge struts it is assumed that some of the load from the un-supported ridge will travel down the rafter to walls 'A' and 'B'. The RLWs for walls A & B are increased accordingly.
Underpurlin 1 =
x yRLW RLW
BCA
ba 1 23
RLW
Underpurlin 2 =3y
Underpurlin 3 =3y
AS 1684 Span TablesRoof Member Load Impacts – With Ridge Struts
2x
Ceiling load width (CLW) is the width of ceiling that contributes ceiling load to a supporting member (usually measured horizontally).
A B
x
CLW
AS 1684 Span TablesRoof Member Load Impacts – Ceiling Load Width
CLW is used as an input to Span Tables for hanging beams and strutting/hanging beams
Hanging beam
Ceiling jo ist
Hanging beam span
'x '
Hanging Beam Strutting/Hanging Beam
Strutting beam span
Ridgeboard
Underpurlin
Strutting beam
Roof strut
AS 1684 Span TablesRoof Member Load Impacts – Ceiling Load Width
CLW Hanging beam D =2
x
A B C
ED
x y
CLW CLW
FIGURE 2.12 CEILING LOAD WIDTH (CLW)
AS 1684 Span TablesRoof Member Load Impacts – Ceiling Load Width
A B C
D E
yx
CLWCLW
CLW Strutting/Hanging beam E = 2
y
Example: The Strutting Beam Span Table requires a ‘Roof Area Supported (m2)’ input. The strutting beam shown supports a single strut that supports an underpurlin. The ‘area required’ is the roof area supported by the strut.
2
B
2
A
This is calculated as follows:-Roof Area Supported =
Sum of half the underpurlin spans either side of the strut (A/2) multiplied by the sum of half the rafter spans either side of the underpurlin (B/2).
AS 1684 Span TablesRoof Member Load Impacts – Roof Area Supported
A
Stru tting Beam Span
Strutting Beam
Underpurlin
S trut
A/2
B/2
B
AS 1684 Span TablesStrutting Beam Design Example
Inputs requiredWind Classification = N2Stress Grade = F8Roof Area Supported = 6m2
Strutting Beam Span = 2900 mmSingle or Continuous Span = SingleRoof Mass (Sheet or Tile) = Steel Sheet (20
kg/m2)
Roof Area Supported = 6m2
2 x 140 x 45 mm F17 members are adequate
Roof = SheetStrutting Beam Span = 2900 mm
AS 1684 Span TablesStrutting Beam Design Example
Return to menuAS 1684 Span TablesWall Framing
WALL FRAMING
Return to menuAS 1684 Span TablesWall Framing
T im b e r o r m e t a l b r a c in gTo p p la t e
B o t t o m p la te
J a c k s tu d
J a m b s t u d
W a l l i n te r s e c t io n
N o g g in g
C o m m o n s t u d
L i n te l
S h e e t b r a c in g
Return to menuAS 1684 Span TablesWall Studs Design Example
Inputs requiredWind Classification = N2Stress Grade = MGP10Notched 20 mm = YesStud Height = 2400 mmRafter/Truss Spacing = 900 mmRoof Load Width (RLW) = 5000 mmStud Spacing = 450 mmRoof Type = Steel Sheet (20 kg/m2)
Wall Framing – Wall Stud Size
Inputs required• Wind Classification = N2• Stress Grade = MGP10• Notched 20 mm = Yes• Stud Spacing = 450 mm• Roof Type = Steel Sheet (20 kg/m2)• Rafter/Truss Spacing = 900 mm• Roof Load Width (RLW) = 5000 mm• Stud Height = 2400 mm
Inputs required• Wind Classification = N2• Stress Grade = MGP10• Notched 20 mm = Yes• Stud Spacing = 450 mm• Roof Type = Steel Sheet (20 kg/m2)• Rafter/Truss Spacing = 900 mm• Roof Load Width (RLW) = 5000 mm• Stud Height = 2400 mm
Simplify tableAt least 5000mm
70 x 35mm
MGP10 wall studs
are adequate
2006
Return to menuAS 1684 Span TablesTop Plate Design Example
Inputs requiredWind Classification = N2Stress Grade = MGP10Rafter/Truss Spacing = 900 mmRoof Load Width (RLW) = 5000 mmStud Spacing = 450 mmRoof Type = Steel Sheet (20 kg/m2)
Wall Framing – Top Plate Size
Simplify table
Inputs required• Wind Classification = N2• Stress Grade = MGP10• Roof Type = Steel Sheet (20 kg/m2)• Rafter/Truss Spacing = 900 mm• Tie-Down Spacing = 900 mm• Roof Load Width (RLW) = 5000 mm• Stud Spacing = 450 mm
At least 5000mm
2 x 35x 70mm
MGP10 top plates are adequate
2006
AS 1684 Span TablesWall Framing – Wall Lintel Design Example
Inputs requiredWind Classification = N2Stress Grade = F17Opening size = 2400 mmRafter/Truss Spacing = 900 mmRoof Load Width (RLW) = 2500 mmRoof Type = Steel Sheet (20 kg/m2)
Wall Framing – Lintel Size
Simplify table
Inputs required• Wind Classification = N2• Stress Grade = F17• Roof Type = Steel Sheet (20 kg/m2)• Roof Load Width (RLW) = 2500 mm• Rafter/Truss Spacing = 900 mm• Opening size = 2400 mm
Inputs required• Wind Classification = N2• Stress Grade = F17• Roof Type = Steel Sheet (20 kg/m2)• Roof Load Width (RLW) = 2500 mm• Rafter/Truss Spacing = 900 mm• Opening size = 2400 mm
Use 3000mmUse 1200mm
A 140 x 35mm
F17 Lintel is
adequate
2006
Return to menuAS 1684 Span TablesFloor Framing
FLOOR FRAMING
Floor bearers
Floor joists
AS 1684 Span TablesFloor Framing – Floor Members
Perimeter Brickwork
Platform Floor Sheets
Bearers are commonly made from hardwood or engineered timber products and are laid over sub-floor supports.Bearers are sized according to span and spacings – typically a 1.8m (up to 3.6m) grid
Bearer spanBearer spacing Bearer SpanBearer Spacing
AS 1684 Span TablesFloor Framing – Floor Bearers
AS 1684 Span TablesFloor Framing – Floor Load Width Example
If a = 900 mm x = 2000 mm y = 4000 mm
FLW A = 1900 mmFLW B = 3000 mmFLW C = 2000 mm
4500
Simple rectangular shaped light-weight home
Gable Roof =25o pitch
Steel Sheet = 20 kg/m2
Wind Speed = N2
Wall Height = 2400 mm
Elevation
3600
Section
Floor joistsBearers
AS 1684 Span TablesFloor Framing – Bearer and Floor Joist Example
Bearer A
And a floor load
Supports both a Roof Load
3600
Section
1800
Floor Load Width (FLW) Bearers at 1800 mm centresFLWA = 1800/2 = 900 mm
Floor Joists at 450 mm crs
AS 1684 Span TablesFloor Framing – Bearer Design Example
x ya b
RLW RLW
A B
ayx
2
Roof Load Width (FLW) for Wall A =
AS 1684 Span TablesFloor Framing – Bearer Design Example
a = 496 mm
x = 1986 mm
Total RLW On Wall A = 1986 mm (say 2000 mm) + 496 mm (say 500 mm) = 2500 mm
AS 1684 Span TablesFloor Framing – Bearer Design Example
Inputs required• Wind Classification = N2• Stress Grade = F17• Floor Load Width (FLW) at A = 900 mm• Roof Load Width (RLW) = 2500 mm• Single or Continuous Span = Continuous• Roof Mass (Sheet or Tile) = Steel Sheet (20 kg/m2)• Bearer Span = 1800 mm
Floor Framing – Bearer Size
2006
Inputs required• Wind Classification = N2• Stress Grade = F17• Floor Load Width (FLW) at A = 900 mm• Roof Mass (Sheet or Tile)= Steel Sheet
(20 kg/m2) Single or Continuous Span = Continuous
• Roof Load Width (RLW) = 2500 mm• Bearer Span = 1800mm
Inputs required• Wind Classification = N2• Stress Grade = F17• Floor Load Width (FLW) at A = 900 mm• Roof Mass (Sheet or Tile)= Steel Sheet
(20 kg/m2) Single or Continuous Span = Continuous
• Roof Load Width (RLW) = 2500 mm• Bearer Span = 1800mm
Simplify table
Use 1200mm table
Use 4500mm
2 x 90 x 35mm F17 members joined
together are adequate
AS 1684 Span TablesFloor Joist Design Example
Inputs requiredWind Classification = N2Stress Grade = F17Roof Load Width (RLW) = 0 mm(just supporting floor loads)Single or Continuous Span = Continuous (max 1800)Roof Type = Steel Sheet (20 kg/m2)Joist Spacing = 450 mm
Floor Framing – Floor Joist Design Example
Simplify table
2006
Inputs required
Wind Classification = N2
Stress Grade = F17
Joist Spacing = 450 mm
Roof Type = Steel Sheet (20 kg/m2)
Single or Continuous Span = Continuous (max 1800)
Roof Load Width (RLW)= 0 mm
Joist span = 1800mm
Inputs required
Wind Classification = N2
Stress Grade = F17
Joist Spacing = 450 mm
Roof Type = Steel Sheet (20 kg/m2)
Single or Continuous Span = Continuous (max 1800)
Roof Load Width (RLW)= 0 mm
Joist span = 1800mm
At least 1800mm
90 x 35mm F17 floor joists at 450mm crs
are adequate
Further Information
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