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Mrtfc Engineering | Framing (Construction) | Flooring
Multi-Residential Timber Framed Construction for Class 2 & 3 Buildings Structural Engineering Guide
MAG04_2010_C1
Anchor Bolts in Light-Frame Construction at Small Edge Distances.pdf
MULTI-RESIDENTIAL TIMBER FRAMED CONSTRUCTION STRUCTURAL ENGINEERING GUIDE FOR CLASS 2 AND 3 BUILDINGS UP TO 3 STOREYS (4 storeys where ground floor is masonry for car parking) NATIONAL TIMBER DEVELOPMENT COUNCIL .
Design and construction manual for Class 2 and 3 Buildings . Other publications complementary to the use of this publication include the following:- AS 1170 Loading Code – Standards Australia AS 1684. and as successful design and construction depends upon numerous factors outside the scope of this publication. the National Timber Development Council or the Forest and Wood Products Research and Development Corporation accepts no responsibility for errors in.4 Timber Structures. They are offered only for the purpose of providing useful information to assist those interested in technical matters associated with the specification and use of timber and timber products. opinions. This publication which is written in limit state format is primarily intended for use by structural engineers. Whilst every effort has been made to ensure that this publication is in accordance with current technology.2 Timber Structures. The aim of this publication is to provide notes and criteria applicable to the structural design of Class 2 and 3 Buildings up to 3 Storeys in height (for Class 2 Buildings. Design and construction manual for Class 1 Buildings – National Timber Development Council FWPRDC MRTFC . Part 4 – Fire-resistance of structural timber members MRTFC .National Timber Development Council FWPRDC © NTDC/FWPRDC The information. PREFACE This publication is intended to complement a range of other literature published by the Forest and Wood Products Research and Development Corporation (FWPRDC) and Standards Australia and should be read in conjunction with these publications. . 5 – Fire and Sound Rated Wall and Floor/Ceiling Summary . it is not intended as an exhaustive statement of all relevant data. or omissions from. advice and recommendations contained in this publication have been prepared with due care.1 Residential timber-framed construction.National Timber Development Council FWPRDC MRTFC – Information Bulletin No. nor for specifications or work done or omitted to be done in reliance on this publication. up to 4 Storeys where the ground floor is for car parking and is constructed in masonry or concrete). Part 1: Design Criteria – Standards Australia AS 1720. Part 1 – Design methods AS 1720. this publication.
Contents Page Introduction 1 Scope 1 Structural Considerations ! Designing for Shrinkage 2 ! Building Mass 2 ! Foundations and Footings 2 ! Structure Stability 3 ! Design Loads 3 Dead and Live Loads 3 Wind Loads 3 Earthquake Loads 7 ! Shear Walls and Diaphragms 7 ! Member Design 8 Roof and Ceiling Framing 9 Wall Framing 9 Floor Framing 9 ! Load Combinations and Deflection Limits 10 ! Load Capacity of Fire Rated Wall and Floor Systems 11 ! Effective Height of Fire Rated Walls 11 ! Fire Ratings for Solid Timber 12 .
It is not intended that they replace or negate the engineers need or responsibility to make reference to the appropriate loading and material standards or building regulations. The guidelines given are intended to highlight some of the structural design considerations that may be new or not familiar to engineers who regularly work with timber in domestic construction only (Class 1 buildings) or for those who usually design in other construction materials. it is necessary. These guideline notes and criteria have therefore been prepared to assist engineers in the structural design of these buildings. particularly for 3 and 4 storey timber framed buildings. 2 and 3 buildings. fire and sound ratings. Construction details also continue to be refined and improved to support the value of MRTFC. and the general philosophy and reliability associated with design. -1- Introduction Since MRTFC was introduced in Australia in 1996 its acceptance and use is now widely acknowledged as a very economical and efficient form of construction for Class 1. The following provides some guidance on these aspects. Structural Considerations Although many aspects of the design of single detached timber framed dwellings may be applied to Class 2 and 3 buildings. These differences give rise to a number of structural considerations above those applicable to normal domestic construction or alternatively that may vary from multi-storey masonry construction. More economical fire and sound rated timber wall and floor/ceiling systems are being tested and certified to facilitate this form of construction and to improve efficiencies. structure stability (increased height). Class 2 and 3 timber framed buildings differ in their design considerations from normal domestic Class 1 buildings in a number of aspects including dead and live loads. Generally these buildings in timber are: ! of lighter mass than full masonry construction ! relatively tall and slender ! required to carry greater dead loads (fire and sound rated walls and floors) and live loads than Class 1 buildings ! required to accommodate larger numbers of people ! constructed using specific methods for attachment of linings to achieve fire and sound ratings. Scope This publication provides guidelines and notes to assist engineers performing structural calculations and checks on timber framed Class 2 and 3 buildings up to 3 storeys in height (four storeys where the ground storey is of concrete/masonry construction). . to consider the implications of design criteria and loads that are specific to this form of construction.
the effect of a lower building mass also impacts upon the structures overturning stability. Total shrinkage will vary markedly depending upon the combinations of wall and floor frame selected and the building practice adopted. These standards are therefore generally applicable to Class 1 buildings of up to two storeys. When designing for shrinkage the following should be considered:- ! reduce overall shrinkage ! avoid differential shrinkage ! provide clearances to brickwork and masonry and allow for shrinkage with respect to plumbing. Foundations and Footings AS 2870 Residential Slabs and Footings. provides general guidance for detached residential construction of up to two storeys. breadth and reinforcing required in footings. however for timber framed Class 2 and 3 buildings they would also be applicable for up to two storeys. This design consideration is discussed later. -2- Designing for Shrinkage (Where unseasoned timber is used) Note: In general. Whilst this affords considerable savings in minimising the depth. walls and roofs has a mass of less than one-half of that of full masonry construction (with timber roof frame). the use of unseasoned timbers in 2 or 3 storey construction should be limited to minimise shrinkage problems. Some additional limitations apply where first floors are of suspended slab construction. in buildings of one or two storeys ! use of seasoned or engineered products for joists in lieu of unseasoned timber. For 3 and 4 storey timber framed construction. Shrinkage considerations for multi-residential construction are similar to normal domestic construction except. Potential problems that can be associated with shrinkage can be minimised or eliminated through:- ! limiting the use of unseasoned hardwood for wall framing only. . footings should be designed in accordance with AS 3600 Concrete Structures or if required AS 2159 Piling – Design and installation. ! reduce one level of shrinkage by using joists and bearers in line (joists supported off bearers using framing brackets) ! use of seasoned wall and floor framing throughout ! eliminating differential shrinkage ! making allowance for "calculated" shrinkage relative to clearances to masonry or other freestanding elements Building Mass Full timber framed construction (including masonry veneer) using timber framed floors. for 2 and 3 storey buildings the potential for greater total shrinkage must be considered where unseasoned timber is used together with the effect shrinkage may have on the integrity of fire and sound rated walls and floors.
For 3 or 4 storey construction in built up non-cyclonic areas. these effects must be considered usually requiring specific engineering design of members etc. This increase in velocity will increase design wind pressures by about 15- 20%. full timber framed multi-residential construction has much less mass than traditional full masonry. lateral wind forces on lower storeys.3 should also be considered. In addition. More detailed dead loads for walls. For higher or lower design wind speeds. The narrower the width of these buildings and the greater the design wind speed the more that overturning of the structure becomes critical as a structural design consideration.1 and AS 1170. similar forces per unit width would apply except for buildings with gable or skillion ends where a slight increase will apply to account for the increased flat area of wall. floors and walls are shown alongside. no topographic effects) typical ultimate limit state design wind speeds would be around 50 m/s. ultimate limit state) exceeds 50 m/s and or the height to width ratio exceeds approximately 1. For alpine and sub-alpine areas snow loads in accordance with AS 1170. Typical Design Loads ! Dead and Live Loads AS 1170. As can be seen from Figure 1. Earthquake forces can be determined from AS 1170.2 provide the basis for determination of appropriate dead. This can be determined by reference to AS 1170. where appropriate for comparative purposes the corresponding loads for full masonry construction i. with typical height to width ratios of around 1.e. A summary of some typical loads are given in Table 1 and. For 3 or 4 storey construction.5:1.(Dead Load Column). this type of multi-residential construction often has end elevations which are "slender". live and wind design loads and load combinations applicable to Class 2 and 3 multi-residential construction. ! Wind Loads Building height is a significant input for determination of design wind speed.5:1. are quite high and will need to be resisted by 'significant' bracing walls as is shown in the example in Figure 1. the lateral forces increase or decrease in proportion to the square of the velocity. the additional storey height/s could be expected to increase the design wind velocity normally associated with two storey construction by around 8 to 10% (at a particular site).4 and these are described in more detail later. which when coupled with increased DL's associated with fire rated construction could significantly effect member design when compared to normal Class 1 buildings. These of course may be able to be reduced for the lower levels of the building. It is recommended that an engineering check of overturning be carried out where the wind velocity (Vu. Typical lateral wind forces for an ultimate limit state design wind speed of 50 m/s are provided in Table 4 for 3 or 4 storey multi-residential construction.2 . For wind blowing normal to the width of the building. -3- Structure Stability As is shown in Table 1 . roofs and floor/ceilings are given in Tables 2 and 3. for relatively low design wind velocities. For 3 or 4 storey construction. (terrain category 3.
1 specifies a concentrated load of 1. For lateral wind forces refer to Table 4.(4) Load(3). 1.5 kPa for that portion of floor live load considered permanent.External Line load 2.5 (lining.1.1.0(5) 4.1.4(6) - (kN) Walls . 1.0 - Floors (Including fire rated (kPa) ceiling) .25 Concentrated . . 3.0.2 . For Class 1 buildings. 4.12  or and fire rated ceiling)  A  0.1 kN. Wind loads given are typical gross ultimate limit state pressures normal to the relevant surface. Refer to AS 1170.Hallways. frame and 110 mm (kN/m) (0. The loads shown above are “unfactored”.1 .5 - (kN/m) (live load on edge of balcony) Notes: 1. 6.1 .7 if lightweight clad) brick) .0(5) 2. - (kN/m) UDL 1. Concrete floor mass based on 150 thick slab plus covering. . 1.5 - (kN) UDL 1.General Areas Concentrated . For Regions A and B typical ultimate limit state design wind speeds of between 45 and 53 m/s are appropriate for buildings to 15 m high in Terrain Category 3.0(5) 4. . . The determination of “Limit State” design load combinations must be done by reference to Table 5 5.4xheight (m) 4. . The floor DL's given include an allowance of 0.8  Roof UDL Sheet Roof Tile Roof .1 for possible floor live load reduction factors.4 4. (kPa) Passages etc. 1.1 .55)xheight (m) 2. -4- TABLE 1 TYPICAL DESIGN LOADS (UNFACTORED) FOR CLASS 2 AND 3 BUILDINGS (Ultimate limit state design wind speed 50 m/s – Non-cyclonic areas) Element Load Type Dead Load(1). 2. framing (kPa) 0.05  + 0. .55 1.1 .8 - (kN) UDL 1. 1.45 . Concentrated . 4. AS 1684.4 4.4 4.(4) Full Timber Frame Masonry/ Construction Concrete  1.7 (Includes roofing.(4) Live Wind Load (2).Internal Line load (0.0 - Balconies (kPa) Concentrated .0 - .
7 Carpet and underlay on resilient mounts Timber flooring ceramic Flooring + joists + fire rated lining 0.5 both directions fire rated plasterboard lining 60/60/60 Lightweight cladding + fire rated sheeting + single stud + 0.85 tiles and underlay on resilient mounts 90/90/90 Timber flooring Flooring + joists + fire rated lining 0.5 Staggered stud wall + fire rated lining + insulation 0.55 RISF ceiling Tile roof Tile roof + framing + fire rated 1.6 TABLE 3 TYPICAL DEAD LOADS FOR FIRE AND SOUND RATED ROOFS AND FLOOR/CEILINGS Element FRL Roofing/flooring System Dead Load (kPa) (1) Roof and Ceiling Ceiling 60 minutes N/A fire rated ceiling lining 0.6 cement lining + insulation 90/90/90 Single stud wall + fire rated lining + insulation 0.2 from outside in (note: mass of brick veneer not included) 90/90/90 110 mm brick + single stud + fire rated lining 0.75 Carpet and underlay on resilient mounts Timber flooring ceramic Flooring + joists + fire rated lining 0.55 Double stud wall + fire rated lining + insulation 0.9 tiles and underlay on resilient mounts Balconies 60/60/60 Timber Flooring Flooring + joists + fire rated lining 0.5 Carpet and underlay on resilient mounts Timber flooring ceramic Flooring + joists + fire rated lining 0.05 ceiling Floor/Ceilings General areas 30/30/30 Timber flooring + Flooring + joists + fire rated lining 0. Refer to Load Combinations.7 on resilient mounts Timber flooring + Flooring + joists + fire rated lining 0. -5- TABLE 2 TYPICAL DEAD LOADS OF FIRE AND SOUND RATED WALLS Wall FRL System Dead Load (kPa) External Brick Veneer 60/60/60 110 mm brick + single stud + fire rated lining 0.3 both directions (note: mass of brick veneer not included) Clad Wall 60/60/60 Lightweight cladding + fire rated sheeting + single stud + 0.55 cement lining + insulation Double stud wall + fire rated plasterboard and fibre 0.2 both directions (note: mass of brick veneer not included) 90/90/90 110 mm brick + single stud + fire rated lining 0. .7 both directions fire rated plasterboard and fibre cement lining 90/90/90 Lightweight cladding + fire rated sheeting + single stud + 0.5 kPa should be added to the dead loads of floor systems to account for the permanent proportion of floor live loads.5 cement lining + insulation Staggered stud wall + fire rated plasterboard and fibre 0.85 tiles and underlay Note : An additional allowance of approximately 0.7 tiles and underlay on resilient mounts 60/60/60 Timber flooring Flooring + joists + fire rated lining 0.4 plasterboard lining + insulation 60/60/60 Single stud wall + fire rated plasterboard and fibre 0.7 both directions fire rated plasterboard and fibre cement lining Internal 60/60/60 Single.25 RISF Roof and ceiling 60 minutes Sheet roof Sheet roof + framing + fire rated 0.65 Timber flooring ceramic Flooring + joists + fire rated lining 0.65 on resilient mounts Timber flooring + Flooring + joists + fire rated lining 0. staggered or double stud wall + fire rated 0.
1 kPa 9.7m wall height and 0.3 (14) Ground 6 1.7) 1.8) 1.7 m of 6 kN/m rated structural plywood 8.6) 1.7) 1.0 (1.9) 0.3 (13) 1.3 (13) 10 1.2 (5. -6- WIND 20O 1.7) 1.2 (14) 1.3) 1.3 (14) 1.7 m of 6 kN/m rated structural plywood WALL ‘B’ – 7.1 (6.1 (11) 1. .2 (8.2 (9.8) 1.0) 1.8) 1.82kPa x 2.85 (1. wind pressure = 0.0 m other side 1.4 (16) 1.1 (4.3 (12) 1.9) 3rd level 8 1.2 (9. brace wall spacing = 7 m Therefore Racking force on wall A (@ 7m spacing) = 0.2 (5.9) 0.7) 1.0 (3.3m floor depth).0) 0.0) 1.1 (5.3 (17) 12 1.2 (8.8) 0.2 (9.1 (11) 1.8) 1.0 (4.6) 1.74 (2.8) 0.1 (4.89 (2.5) 10 1.3 (14) 1.8) 1.6) 2nd level 6 1.2 (14) 1.79 (1.87 (1.3 (12) 1.8) 1.91 (1.4 m of 6 kN/m rated structural plywood T C WALL ‘C’ – 11.9) 0.456 m 0.3 (12) 8 1.1 (10) 1.2) 1.9) 1.79 (1.3 (14) 1.2 (14) 1.0 (5.2 (9.9) 0.1 (7.3 (14) 1.95 (1.2 (9.0 (6.1 (5.9) 1.1 (1.1 (9.7 m long Full plywood one side part plywood other side TYPICAL BRACING REQUIREMENTS FOR WALLS SPACED AT 7 m.1 (6.2 (5.7) 1.1 (5.4 m long Full plywood one side part plywood 9.0 m WALL B 7.8) 0.2 (15) 1.1 kN Since Wall A has 6kN/m bracing capacity.3 (16) 1.2 (10) 1.9) 1.2 (14) 1.0 (3.82kPa Area of elevation = height of elevation x brace wall spacing Height of elevation=½ wall height+roof height=2.7) 1.1 (3. 2.3 (14) 1.2 (9.1/6 = 2.2 (7.82 (2.3 (14) 1.8) 1.0 (1.456 =2.6) 8 1.2 (9.0 m FIGURE 1 EXAMPLE OF "BRACING" FORCES FOR ULTIMATE LIMIT STATE WIND SPEED 50 m/s Example Wall A .3 (12) 1.2 (9.0) 1.2 (5.3 (14) 1.2 (5.2 kPa WALL C 11.3) 1.7) 12 0.6) 1.1) 1.2 (9.8) 0.0) 12 1.3 (17) 10 1.7m TABLE 4 TYPICAL LATERAL WIND FORCES ON A 4 STOREY MULTI RESIDENTIAL BUILDING (Ultimate limit state design wind speed of 50 m/s) Level of Building Wind Pressure 'p' (kPa) on elevated area of building Building Width (m) Values in bracket are Wind Force ‘F’ (kN/m) per unit length of building Roof Slope (Degrees) 5 10 15 20 25 30 Top level 6 1.82 (2. SEPARATING SOLE OCCUPANCY’S WALL ‘A’ – 2.3) 1.85 (3.8) 1.8) 1. The floor to floor height assumed in the above table is 3.0 m (2.7) 1.70 (2.2 (14) 1. The force per unit length of building can be determined by multiplying the pressure kPa by the height of elevation at the desired level.2 (3.1 (5.7m long Part plywood one side 1.3 (9.3 (8.9) 1.806 x 7m = 16.2 (14) 1.2 (9. the length of braced wall required = 16.3 (7.3) 1.2) 10 1.7) 1.82 kPa 2.806 m WALL A 2.3 (17) 1.6) 1.3) 6 1.1) 0.7/2+1.3 (16) 1.8) 1.2 (5.0) 1.8) 1.Top level: From Table 4.806 m.98 (1.2 (14) 1.3) 1.1 (5.1 (6.3 (18) Notes: 1.1) 1.8) 0.3 (9.3 (13) 12 1.3 (7.3 (16) level 8 1.2 (14) 1.9) 0.2 (10) 1.
centre of mass or bracing resistance) which would require static analysis. overturning may also need to be considered. Note: Unlike wind forces (that are a function of area of elevation). These stresses. For wind/earthquake tension stresses. Where the soil profile for a site is unknown. One exception to this is in Category B for irregular buildings (either geometry.5 should be applied. studs can be designed in tension. Note: The information given in NAFI Datafile SS6 is in permissible stress format and will have to be converted to limit state format to be compatible with this publication. For multi-storey construction. Alternatively. For long slender buildings. . Studs can be designed in compression for the combined DL plus chord compression stress due to wind or earthquake forces. provides guidance and design procedures to cater for earthquake forces on multi-residential construction. These systems provide the inherent strength for this 3 dimensional "cubicle" form of construction. For most major Australian cities. earthquake forces are a function of building mass. In addition. -7- ! Earthquake Loads AS 1170. B or C would apply depending upon the product of the acceleration co-efficient and site factor (a. Shearwalls and Diaphragms Three storey Class 2 and 3 buildings can be constructed using conventional "domestic" framing techniques which rely upon the structural action of horizontal diaphragms and vertical shearwalls in combination to resist lateral and overturning loads.4 and resistance to these shear forces detailed similar to the wind loads. a "default" site factor of 1. tie-down bolts can be installed for the full height of the walls as well as for connecting storeys. the shear forces can be determined from Section 6 of AS 1170.s. this gives rise to a Design Category A or B which would not require a static analysis of the forces acting on the building as timber framed structures are classified ductile. For cases that require static analysis. Multi-residential construction up to 3 or 4 storeys is classified as a Type 1 Structure under this code and as such. either tension or compression. result from the bending action induced in the shearwall or diaphragm plus the shear due to lateral forces. This may also be true for some manufacturer’s shearwall or diaphragm information.4 "Minimum Design Loads on Structures . most sheet manufacturers have relevant design data published giving shear or bracing capacities for their products. earthquake forces may dictate shear (bracing strength) requirements parallel to the building length.). Some shearwall and diaphragm design considerations that need to be addressed for up to 3 storey Class 2 and 3 buildings are as follows :- ! allowing for secondary stresses in shearwall or diaphragm chord members (studs and plates).Earthquake Loads". Earthquake Design Category A. Design procedures for shearwalls and diaphragms are published in the NAFI Timber Manual - Datafile SS6 (See references). Therefore earthquake forces do not decrease (as normally occurs with wind) normal to the width of the building. the need to resist lateral wind or earthquake forces increases with the height of the building. and as mentioned previously.
AS 1684. This requirement caters for the fact that wind and gravity forces are usually as high during construction as at completion. Because of the higher load levels expected with Class 2 and 3 Buildings. and the use of conventional member sizes. ii) the ultimate limit state design wind speed does not exceed 50 m/s.1 specifies higher levels of live load (floors in particular) for Class 2 and 3 Buildings. specific engineering design of the structural framework should be carried out using the relevant loading codes and AS 1720. particularly in the lower levels as lateral loads may be quite significant. studs bearing on plates and in some instances tension perpendicular to grain etc. ! Live Loads . lining and roofing materials). Part 1:Design criteria”. the bracing or diaphragm capacity of the system should be ignored as there is no direct rigid connection to the framing.AS 1170. Unless these systems have been specially rated.1 for Class 1 Buildings are also applicable to members in Class 2 and 3 Buildings however the additional load combinations given in AS 1170. ! during construction. as well as the fact that construction loads are often eccentric (stacked flooring.1 details the relevant load combinations that are required to be considered in design. ! Wind Loads . whilst specifically written to for Class 1 Buildings.1 "Timber Structures – Part 1:Design methods". sufficient permanent bracing must be installed in the lower levels of the building (a minimum of 60% of the total permanent bracing is suggested) prior to the upper levels being framed up or the roofing installed. including:- ! Dead Loads . Member Design For Class 2 and 3 Buildings. as the basis of design.Due to fire and sound rating requirements these are usually much greater than traditional domestic construction due to the extra sheeting and insulation required.1 “Residential timber-framed construction. can also be used as a general guide for the design of members in Class 2 and 3 Buildings provided the appropriate adjustments are made to the relevant criteria. Refer to AS 1720. ! normal sheet flooring directly fixed to joists will provide sufficient diaphragm action to transfer lateral loads between shearwalls walls spaced up to 14 m provided:- i) the floor diaphragm span to depth ratio does not exceed about 2:1.Care needs to be taken to ensure that the correct design wind speed is determined due to the increased height of 3/4 storey buildings (the terrain category/height multiplier will be greater than normally determined for two storey Class 1 Buildings resulting in higher pressures on members). -8- ! many fire and sound rated wall and floor/ceiling systems rely upon resiliently mounted sheeting (usually plasterboard) for noise control purposes.1. specific checks should also be carried out on stresses perpendicular to grain e.1 for earthquake and fire may also be relevant to the design of some members and may need to be considered. ! check resistance of tie-down fixings for shear loads. The general load combinations given for the framing members in AS 1684.g. ! Load Combinations – AS 1170. .
insulation.1 from normal domestic design.1 permits live load reduction factors to be applied to members supporting areas in excess of 23. iii) Floor vibrations have been demonstrated to be of concern for typical lightly loaded domestic Class 1 Building floor framing systems and a design check has been included in AS 1684. joists and ceiling lining.0 kPa or 1. it is still recommended that the serviceability check for vibration given in AS 1684.8 kN and 4. For some lower storey loadbearing wall members this reduction may be applicable. . ! Wall Framing i) For walls required to be fire rated. ii) For lower storey loadbearing walls.5 kPa. ii) AS 1170.0 or 4. walls and floors.7 kPa.0 and 4. AS 1720) may not be as great as for direct fixed ceilings. higher uniformly distributed floor Live Loads of 2.1 to cater for this.e. ii) For suspended or resiliently mounted ceilings. These UDL's for Class 2 and 3 Buildings have corresponding point live loads of 1.1 specifies floor live loads for Class 2 and 3 Buildings of 2. the loadsharing capacity of the system (k9.5 kN that also have to be considered independently. dynamic effects may not be as critical as member sizes may be controlled by these other load considerations.9 kPa are suggested to cater for flooring. a percentage of the floor live load should be added to the DL to account for that portion of floor live load that is permanent. the dead load of the floor has been increased by 0. 2 layers of 16 mm fire resistant plasterboard equals 0.5 kN/m along the edge of the balcony. This may also effect lateral restraint assumptions (k12).1. In AS 1684. ! Floor Framing i) Floor dead loads will be increased due to the need to provide additional sheeting and insulation to the floor/ceiling system to cater for sound and fire rating requirements. Note: AS 1170. For Class 2 and 3 buildings with higher floor dead and live load requirements.7 kPa to 0.) vs 0. increased dead loads due to the additional weight of either one or two layers of fire rated board need to be considered in addition to the heavier mass of any fire rated overlying ceilings. iii) Wind loads may be greater than normal due to increased height of building. these layers will usually be required both sides of the wall increasing the wall DL's up to about 0.5 kPa to account for this and this is also considered appropriate for the general floor areas of Class 2 and 3 Buildings. iii) Wind loads on walls may also be greater due to increased height of the building. refer to Table 3. respectively compared to Class 1 Buildings of 1. In addition. Refer to Table 2.0 m². Except in external brick veneer walls.1 be carried out. Live loads on balconies are specified as 4.25 kN/m² (approx.0 kPa may need to be considered alone or in combination with other live and wind loads and also higher floor dead loads (to cater for fire rated ceilings to the underside of the floors). -9- Some specific loading considerations for various members are as follows:- ! Roof and Ceiling Framing i) Dead Loads are increased due to the normal requirement of providing a ceiling with 1 hour resistance to incipient spread of fire i. Refer to Table 3. Typical DL's of around 0.0 kPa for general areas and hallways etc. Irrespective.
5Q2 Ws ∆3 ≤ L/200 1.8 G2 + kc (W↑ + W →) 1.5Q2 1.25G1 Ws ∆3 ≤ L/150 20 .5Q2 Q2 ∆2 ≤ L/270 0.25G1 + 1.8 G1 + W↑ .5 ∆2 ≤ L/200 3 1. Top Storey 1.25G1 + kc (W ↓ + W →) 0. Lower Storey 1.4. Roof Beams 1. TABLE 5 TYPICAL LOAD COMBINATIONS AND DEFLECTION LIMITS (Limit State Design) Member Strength Deflection Limits Load Combinations Load Type Ratio Max (mm) Rafters.25G1 + 1.25G2 G2 ∆1 ≤ L/300 15 Floor Loads Only 1.5Q5 Ψs Q6 ∆3 ≤ L/180* 4.25G1 + 1.5Q4 or 1.5Q5 0.25G1 + W ↓ Ceiling Joists.25G1 + W ↓ Wall Studs 1.25G2 + W ↓ 0.25G1 + 1.25G1 + 1.25G1 + 1.5Q3 Ψs Q4 ∆2 ≤ L/250 15 1. 1.1) . It should be noted that these load combinations are applicable to limit state design.25G1 G1 ∆1 ≤ L/300 etc.25G1 + W → (where W → = 0.25G1 + 1.8 G1 + W↑ .5Q1 Loadbearing 1.25G2 Ws ∆3 ≤ L/150 20 Loadbearing 1.5Q1 Q2 ∆2 ≤ L/200 3 Loadbearing 1.5Q6 *L = overhang (2mm max under 1 kn point load refer AS 1684.5 kPa as a W s = 0.25G2 G2 ∆1 ≤ L/200 3 Loadbearing 1.25G2 G2 ∆1 ≤ L/300 10 1.25G1 + 1.5Q5 1.g tile) Wall Plates 1.25G1 + W ↓ 0.25G1 + 1.25G2 + W ↓ 0.5Q1 Q2 ∆2 ≤ L/250 1. Lower Storey 1.25G1 + 1.8 G2 + W↑ Lintels 1.25G1 G1 ∆1 ≤ L/400 12 Hanging Beams 1. 1.8 G1 + W↑ 1.25G1 + 1. Top Storey 1.5Q3 Q4 ∆2 ≤ L/360 9 1.5 ∆3 ≤ L/360 8 "serviceability" component) kPa (for brittle (for brittle surface surface finishes finishes e.5Q5 1.5Q2 1.5Q1 Q2 ∆2 ≤ L/250 15 1.25G1 + 1. Lower Storeys 1.25G1 + 1.25G1 + 1.5 1. .25G1 + W ↓ 0. 1.5Q3 1.25G1 + 1.25G1 G1 ∆1 ≤ L/200 3 .8 G1 + W↑ 1.25G1 + 1.5Q4 or 1.25G2 + kc (W ↓ + W →) W→ Non-Loadbearing 1.10 - Load Combinations and Deflection Limits A summary of some typical load combinations and deflection limits that may be considered in the design of some members for Class 2 and 3 buildings is given in Table 5.5Q4 or 1.25G1 + 1. Top Storey 1.25G1 + 1.5Q4 or 1.25G1 + 1.25G1 G1 ∆1 ≤L/300 10 .8 G2 + W↑ Floor Joist .g tile) e.25G1 + 1.25G1 + 1.5Q3 Ψs Q3.5Q2 Ws ∆3 ≤ L/150 0.25G1 + 1.8 G1 + kc (W↑ + W →) W→ .
unless otherwise indicated. For these wall or floor/ceiling system. G2 = G1 + 0.25 kPa roof live load where A = contributing area m²  A  Q2 = 1.11 - Notes to Table 5: G1 = Sum of all relevant dead loads as appropriate to member under consideration.8  Q1 =  + 0.5 kPa is an allowance for the permanent proportion of floor live load) 1. Effective lateral restraint can be provided by:- 1. there is no need to undertake a fire load condition check.0 kPa uniformly distributed floor live load as appropriate Q5 = 4.2 m centres. floor trusses can substitute solid timber. Nail plated timber.0 kPa partial area floor live load on balconies A ≤ 10 m² = 3. a floor or ceiling system in an adjoining unit or dwelling (can be lower or non fire-rated) 2.5 kN concentrated floor live load as appropriate Q4 = 2.8 kN concentrated load or 1. that the structural load condition governs. .8 kN or 4. Effective Height of Fire Rated Walls The effective height used to calculate the load capacity of a fire-rated wall is the distance between points of effective lateral restraint (usually provided by floors and ceilings). Wall and floor/ceiling systems detailed in Information Bulletin No 5 Wall and Floor/Ceiling Summary have been designed.8 kN/m along edge of balcony Ψs = load factor for short term serviceability live loads = 0.5 kPa (where 0. . for floor/ceiling systems there are no limit in the joist system that can be used. . Additionally.5 kN concentrated live load as appropriate Q3 = 1. a fire-rated floor/ceiling system within the unit or dwelling under consideration 3.0 kPa or 4. a purpose designed and fire-rated lateral restraint system NOTE:- The leaves of double stud wall systems can be effectively tied together at their top and bottom using galvanised iron straps nailed to plates at 1.0 kPa partial area floor live load on balconies 10 < A ≤ 40 m² Q6 = 1.7 except that resultant for floor live loads should not be less than 1. I beams. W↑ = Nett upward wind load W↓ = Nett downward wind load W → = Nett horizontal wind load Ws = Serviceability Wind Load . ∆1 ∆2 ∆3 = Deflection Limits Load Capacity of Fire Rated Wall and Floor/Ceiling Systems Generally tested or certified fire rated loadbearing wall and floor/ceiling systems are required to sustain the normal structural loads and fire load conditions.4 kN or 4.5 kPa uniformly distributed load.
4 AS 1720.59 Assume a 70x70mm cross section of solid timber remains after the fire event.9 kPa W* = 1. k12=0.0 kPa : Dead load.1 φ = 0.19kN = 9.0 kPa AS 1170. Q = 2.12 - Fire Ratings for Solid Timber There will be some applications of exposed timber members (beams.3 assumed Equate W* = Nc = 0.0. Q = 2.5 AS 1170.1 AS 1720.3x40xAc = 9. EXAMPLE: A loadbearing internal column in Class 2 or 3 REFERENCE Type "B" Construction Requirement: FRL 60/60/60 Note: For a column not incorporated in a wall this becomes FRL 60/-/- Assume: The column supports a floor above of 10 m² and the column is 2.1G + ΨQ = 1. AS 1720 "Timber Structures Code Part 4: Fire Resistance of Structural Timber Members" is referenced in BCA as an acceptable procedure for calculating FRL's for solid or glued-laminated timber. The following worked example provides guidance on the application of these procedures. In these instances the only FRL relevant relates to structural adequacy.1 where:.59 Ac Therefore:.1.5 AS 1720. Ac = 4900 mm2 .1 k1=0.1G + ΨQ Cl 2.85 Table G1 AS 1720. Limit State Design Load for Fire.59Ac 19 x103 Hence.1 .94 Table 2.4 –1990 For G = 1.0.4 m high Loads: Live load.1989 Note DL = Flooring + Joists + Ceiling + Insulation etc.8 AS 1720. columns etc) occurring in multiple dwelling construction which require a Fire Resistance Level to be determined for solid timber.1 – 1989 W = WLSD Cl 2.4.1 f’c=40 MPa k4=k6=k11=1.9 x10 = 19 kN CALCULATIONS REFERENCE 1st Approximation: Assume F17 glued-laminated seasoned hardwood φN c = ( k 1 k 4 k 6 k 9 k 11 k 12 f c' A c ) Cl 3.3.94x0. G = 1. Ac= = 1982 mm2 equals approximately 45x45mm 9. WLSD = 1. Table 2. 0 WLSD = 1. Ψ = 0. .85x0.
.6 kN > 19 kN ∴OK Cl 2.75x 2400 S3= = 25.24x40x4900 = 37.85x0.4 Determine effective depth of charring Effective depth of charring dc = ct + 7.4. L = 2400 and d = 70mm 0. g L S3= 13 d Where g13 = 0.5 2  280  Where t = time = 60 mins for FRL 60/-/.0 For k12.94 f’c=40 MPa k4=k6=k11=1.and c = 0.7 70 ρ = 1.13 = 29 Therefore 200 200 K12 = = = 0.24 ( ρS ) 2 ( 29) 2 And φ Nc = 0.4 +    ρ  Where ρ = timber density @ 12% moisture content For Jarrah = 800 kg/m3 and Blackbutt = 900 kg/m3 Use ρ = 800 kg/m3 Other Considerations . the glue used for lamination must be of the resorcinol or phenolic types in accordance with AS 1328 .5 AS 1720.75.7x1. For glued laminated timber.94x 0.3 AS 1720.13 for seasoned F17 Table 3.this is quite suitable for compressive loads.2) . This can be achieved by:- i) Using a standard timber bearing joint with nominal connection for lateral displacement .85 k1=0.13 - Check cross section for fire limit state load of 19 kN φ Nc = φ k1k4k6k11k12(f’cAc) Where:- φ = 0. ii) Protection of the joint using fire resistant materials. (Refer AS 1720. Cl 3.1 ρ S3 = 25. Post connections must also be detailed to achieve the FRL required.
Forest and Wood Products Development Corporation. DESIGN METHODS Standards Australia. AS 1684. 7. NSW. 13.PILING CODE Standards Australia .Sydney. NSW. 8. NSW.4 TIMBER STRUCTURES CODE. PART 1.1 . Melbourne Victoria 2000 14. PART 4 FIRE RESISTANCE OF STRUCTURAL TIMBER MEMBERS Standards Australia.Sydney. AS 1720.EARTHQUAKE FORCES Standards Australia . 1994 2. AS 2870 . AS 2159 .TR 93/5 Building Technology Limited/CSIRO Division of Building Construction and Engineering. AS 1170.2 . Sydney. 1994 12. NSW. 3. TIMBER MANUAL National Association of Forest Industries Canberra Australia 1989 10.LOADING CODE .14 - References 1. NSW. AS 1170.Sydney. MRTFC DESIGN AND CONSTRUCTION MANUAL FOR CLASS 2 AND 3 BUILDINGS National Timber Development Council. 9. PART 1 DESIGN CRITERIA Standards Australia .WIND LOADS Standards Australia . AS 3600 . AS 1720. 1993. Melbourne Victoria 2000 Forest and Wood Products Research and Development Corporation P O Box 69 World Trade Centre Melbourne VIC 8005 Ph: (03) 9614 7544 Fax: (03) 9614 6822 . BUILDING CODE OF AUSTRALIA Australian Building Codes Board . 4. NSW. . NSW. Sydney. NSW. NSW.RESIDENTIAL SLABS AND FOOTINGS Standards Australia .LOADING CODE – DEAD AND LIVE LOAD COMBINATIONS Standards Australia . MRTFC INFORMATION BULLETIN NO 5 – WALL AND FLOOR CEILINGS SYSTEM SUMMARY National Timber Development Council. 6.1 – RESIDENTIAL TIMBER-FRAMED CONSTRUCTION. FIRE RESISTANCE OF TIMBER FRAMED FLOORS AND WALLS .1 TIMBER STRUCTURES CODE.CONCRETE STRUCTURES Standards Australia . 5.Sydney.Sydney. ACT.Sydney.4 . AS 1770. Forest and Wood Products Development Corporation. 11.Sydney. NSW. CSIRO North Ryde.Canberra.LOADING CODE .
Plywood Association of Australia Ltd. Plywood Association of Australia TPC . Kew East Victoria 3102 This publication is a joint venture between the National Timber Development Council Phone (Free Call) 1800 007 463 and the Forest and Wood Products Research and Development Corporation. Fax (03) 6224 1030 TDA (SA) .Queensland Timber Board Tasmania 7000 Phone (03) 6224 1033 TDA (NSW) .Pine Australia Ltd.Australian Timber Importers Federation Fax (03) 9877 6663 FIAT . MULTI-RESIDENTIAL TIMBER FRAMED CONSTRUCTION For informationregarding MRTFCpleasecontact: New South Wales .TAC Timber Advisory Centre of Western Australia FPA . Tasmanian Timber Promotion Board Suite 22.Victorian Association of Forest Industries Fax (07) 3252 4769 Pine Australia FOREST&WOODPRODUCTS RESEARCH & DEVELOPMENT CORPORATION 830 High Street.timber. 55 Salvado Road. Printed June 2000 . Fax (03) 9859 2466 The FWPRDC is jointly funded by the Commonwealth Government and the Australian forest and wood products industry. web www.National Association of Forest Industries PA . Western Australia .Timber Development Association (South Australia) Inc. Surrey Hills New South Wales 2010 Telephone (02) 9360 3088 Fax (02) 9360 3464 Queensland .Timber Development Association (New South Wales) Ltd.Timber Promotion Council of Victoria 3 Dunlop Street.New South Wales Forest Products Association Ltd.Forest Industries Association of Tasmania FIFWA . 11 Morrison Street.Forest & Wood Products Reseach & Development Corporation Telephone (08) 9380 4411 Fax (08) 9380 4477 NAFI .Forest Industries Federation (Western Australia) Inc. Fortitude Valley Queensland 4006 Telephone (07) 3358 1400 Fax (07) 3358 1411 South Australia . Newstead TRADAC .TDA Timber Development Association of NSW 13-29 Nichols Street. Ashford South Australia 5035 Telephone (08) 8297 0044 Fax (08) 8297 2772 Victoria .TAC Timber Advisory Centre Members of the 180 Whitehorse Road.Timber Research and Development Advisory Council (Qld) Queensland 4006 Phone (07) 3854 1228 VAFI .org. Tasmania . Blackburn National Timber Development Council Victoria 3130 Telephone (03) 9877 2011 ATIF . Hobart.TDA Timber Development Association of South Australia 113 Anzac Highway. QTB .TTPB PAA .au/mrtfc © FWPRDC 2000 . Subiaco Western Australia 6008 FWPRDC .TRADAC Timber Research And Development Advisory Council 500 Brunswick Street.
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