The structure of the building includes a complete building system that will ensure that the building elements and fabric are stable and remain in place for the useful life of the facility.
Structural design should consider both the short term functional requirements and a realisation that schools usually have a long service life. Consequently, flexible structural solutions that allow for future adaptability to suit changing planning needs should be considered.
In general terms, framed structures with large column free internal spaces are preferable to load bearing walls.
Structural materials should be chosen from a “Whole of Life” perspective using a select range of preferably sustainable materials designed to provide:
21.01.03 Footings
Design of footings should consider the following:
Footings and slabs, etc. in the vicinity of sewers, pipelines etc. are to comply with the requirements of the relevant Authority.
21.01.04 Floors and Pavements
The detail drawings should show all joint locations and details for floors, pavements and ramps etc.
Pay particular attention to joint layout and details to prevent differential movement between panels at the joints (other than movement perpendicular to the joint) and to prevent shrinkage cracks.
Include hot dip galvanised dowels in joints to both internal and external concrete slabs. Templates should be included to keep dowels in accurate alignment during construction.
21.01.05 Design Loads
Permanent, Imposed and other actions shall be determined in accordance with current ASs for loading unless specified in this Design Guide.
The structures should be detailed so that all parts of the structure are tied together both in horizontal and vertical planes.
The design actions and loads, including values, are to be clearly indicated on the drawings.
21.01.06 Wind Loads
Design for wind actions shall be based on a minimum Importance Level 3. Use a higher Importance Level where required by the BCA.
Determine the appropriate Terrain Category for the site.
The design drawings are to include details of the Terrain Category, Importance Level, Average Recurrence Interval (R), Regional Wind Speed (VR), Wind Direction Multiplier (Md) and any other design factors determined in accordance with the current ASs for wind actions.
Design for internal wind pressures as if some windows are broken with the impact of debris.
21.01.07 Snow Loads
State on the structural drawings the design snow load on roof, ground snow load and probability factor as determined in accordance with the current ASs.
21.01.08 Earthquake Design
The design drawings are to include details of the values adopted for the annual probability of excedance, probability factor, hazard factor, site sub-soil class and the Earthquake Design Category as determined in accordance with the current AS.
If unreinforced masonry is to be used as lateral force resisting elements, the whole structure is to be classified as non-ductile.
Provide adequate separation between structural frames and non-ductile (brittle) elements so that in case of movement during an earthquake, the latter do not attract shear loads unless specifically designed to do so.
21.01.09 Seismic and Wind Resistance
Where appropriate, tie all walls to floors/ceilings/roofs and design the latter to act as plate diaphragms to prevent collapse of walls during seismic ground movements.
Ensure parts of buildings such as window sills, window heads, ceiling system and similar elements have sufficient stability and security to remain completely in place when subjected to either earthquake or wind loading.
21.01.10 Thermal Effects
Take into consideration thermal effects in the design of the structure.
21.01.11 Mine Subsidence
Where the project is located in a Mine Subsidence Area, design the structures to comply with the requirements of the Mine Subsidence Board and submit an application with plans to the Board for approval. Submit work-as-executed plans to the Board.
The effects of mining-induced ground movements must be added to those due to the normal building movements arising from foundation settlement and seasonal moisture changes of the supporting soil.
Deflections in the building structures, arising from mine subsidence are to be considered as additional to all other deflections caused by vertical and lateral loads, as well as by foundation movements caused by soil moisture variations.
Comply with the deflection criteria given in Table B below for wall construction to meet mine subsidence requirements, where required.
21.1.12 Live Loads
Design the structures for a minimum floor live load of 3 kPa, or as specified in Schedule 1 or in accordance with current AS:
SCHEDULE I
LOCATION LIVE LOAD
Wood / metal store 10 kPa
Bulk stores, store in materials room, kiln area, 7.5 kPa
Library (all areas), stage
Other stores, canteen, gymnasium, technology, food 5 kPa
Preparation areas, applied studies, computer areas, arts, plants
Framed walkways / exterior ways 1 kN concentrated load
Design free standing walls to withstand an impact load of 1 kN applied laterally at the top. Assume an impact factor of 2.
Gymnasiums
Design roof structure to support basketball frames and their lifting mechanism, and wall structure to support a horizontal bar at a height of 3600mm from the floor and the associated loads.
Design at least one roof beam to support the following live loads associated with gymnastics (impact effect has been included in values):
Climbing Ropes
|
|
Vertical load |
Horizontal load |
|
|
|
(any direction) |
|
any one rope |
5 kN |
1 kN |
|
6 ropes simultaneously |
2 kN |
0.3 kN |
Roman Rings
Critical Loading
Design the beam(s) to support the most critical combination of the above live loads located anywhere on the one beam.
21.1.13 Structural Deflections
For the design life of the structure ensure that the maximum deflections of structural members and their effect on finishes comply with the serviceability requirements of the structure. In the case of visual elements like fascias, adopt stringent deflection criteria, taking into account the high visibility of the elements. In addition to meeting or exceeding the suggested serviceability limit state criteria table provided in AS/NZS 1170.0, comply with the specific deflection criteria given in Table A.
TABLE A
DEFLECTION CRITERIA - SPECIFIC REQUIREMENTS:
|
ITEM |
STRUCTURAL ELEMENT |
MAXIMUM DEFLECTION |
|
(i) |
Supporting face masonry walls |
span/1000 |
|
(ii) |
Supporting rendered masonry walls |
span/1800 |
|
(iii) |
Floors not supporting brittle elements |
span/500 |
|
(iv) |
Floors supporting brittle elements |
limit to provide adequate serviceability of brittle elements |
|
(v) |
Stud walls under lateral loading |
span/500 |
|
(vi) |
Roof members under: |
|
|
|
a) Dead Load |
span/360 |
|
|
b) Live Load |
span/250 |
|
|
c) Wind Load |
span/150 |
|
|
d) Snow Load |
span/250 |
|
(vii) |
Relative horizontal deflection between adjacent frames at eaves level |
less than the smaller of floor to eaves height/250 and frame spacing/200 |
For members supporting walls or partition elements the relevant deflection is that which occurs after addition or attachment of walls or partition elements.
21.1.14 Mine Subsidence Requirements
Deflections in the building structures, arising from mine subsidence are to be considered as additional to all other deflections caused by vertical and lateral loads, as well as by foundation movements caused by soil moisture variations.
Comply with the deflection criteria given in Table B below for wall construction to meet mine subsidence requirements, where required.
TABLE B
DEFLECTION CRITERIA - MINE SUBSIDENCE REQUIREMENTS:
|
ITEM |
WALL ELEMENT |
MAXIMUM DEFLECTION |
|
(i) |
Load bearing face masonry |
span/3000 |
|
(ii) |
Load bearing rendered masonry |
span/4000 |
|
(iii) |
Non-Load bearing face masonry |
span/1500 |
|
(iv) |
Non-Load bearing rendered masonry |
span/2000 |
|
(v) |
Non-Load bearing articulated face masonry |
span/500 |
|
(vi) |
Non-Load bearing articulated rendered masonry |
span/800 |
|
(vii) |
Non-Load bearing face masonry veneer |
span/300 |
|
(viii) |
Non-Load bearing rendered masonry veneer |
span/500 |
|
(ix) |
Non-Load bearing non-masonry |
span/200 |
The deflections in the above table are those due to mine subsidence which occur after addition or attachment of walls or partition elements.
21.1.15 Bushfires
Design the structures to comply with the requirements current AS for bushfire protection. Refer to the Building Code of Australia section of the Design Guide.
21.1.16 Building Flexibility
Position structural members considering the future flexibility of the structure. Avoid ad hoc placing of columns internally, giving preference to uniformity in layout. Design all internal walls as non-load bearing to enable future flexibility.
21.1.17 Building Floor Slab on Ground
If reinforced concrete is used for building floor slab on ground, other than a waffle slab, the slab shall be minimum 110mm thick and reinforced with not less than SL72 mesh at top.
Provide a thicker slab and/or heavier reinforcement where the design requires.
21.1.18 Bracing
The use of cladding in any form E.g. roof sheeting, wall linings etc., is not acceptable as bracing.
21.1.19 In-ground Concrete Elements
Where aggressive soils are identified in the Geotechnical Report, pay special attention in the design of in-ground unprotected concrete elements due to high acid-sulphate content in subsoils. Use special cements, or protect concrete from direct contact with soils with membrane and the like.
| Location | Live Load | ||||
|---|---|---|---|---|---|
|
|
|||||
| Wood/ metal store | 10kPa | ||||
| Bulk stores, store in materials room, kiln area, library (all areas), stage | 7.5kPa | ||||
| Other stores, canteen, gymnasium, technology, food, preparation areas, applied studies, computer areas, arts, plants | 5kPa | ||||
| Framed walkways / exterior ways | 1 kN concentrated load | ||||
| Vertical Load | Horizontal Load (any direction) | ||||
|---|---|---|---|---|---|
|
|
|||||
| Any one rope | 5kN | 1kN | |||
| 6 ropes simultaneously | 2kN | 0.3kN | |||
| Item | Structural Element | Maximum Deflection | |||
|---|---|---|---|---|---|
|
|
|||||
| (i) | Supporting face masonry walls | span/1000 | |||
| (ii) | Supporting rendered masonry walls | span/1800 | |||
| (iii) | Floors not supporting brittle elements | span/500 | |||
| (iv) | Floors supporting brittle elements | limit to provide adequate serviceability of brittle elements | |||
| (v) | Stud walls under lateral loading | span/500 | |||
| (vi) | Roof members under: | ||||
| - | a) Dead Load | span/360 | |||
| - | b) Live Load | span/250 | |||
| - | c) Wind Load | span/150 | |||
| - | d) Snow Load | span/250 | |||
| (vii) | Relative horizontal deflection between adjacent frames at eaves level | less than the smaller of floor to eaves height/250 and frame spacing/200 | |||
| Item | Wall Element | Maximum Deflection | |||
|---|---|---|---|---|---|
|
|
|||||
| (i) | Load bearing face masonry | span/3000 | |||
| (ii) | Load bearing rendered masonry | span/4000 | |||
| (iii) | Non-Load bearing face masonry | span/1500 | |||
| (iv) | Non-Load bearing rendered masonry | span/2000 | |||
| (v) | Non-Load bearing articulated face masonry | span/500 | |||
| (vi) | Non-Load bearing articulated rendered masonry | span/800 | |||
| (vii) | Non-Load bearing face masonry veneer | span/300 | |||
| (viii) | Non-Load bearing rendered masonry veneer | span/500 | |||
| (ix) | Non-Load bearing non-masonry | span/200 | |||
Prepare drawings for all concrete works, showing layout plans, sections and working details. Show clearly on the drawings all slab thicknesses, beams, sizes, reinforcement, concrete quality and cover, etc.
The design is to comply with a minimum 50 year lifetime durability or higher as required by current AS. All external structural concrete elements and those elements which are adjacent to the cavity of external walls (eg. supporting beams) shall have a minimum exposure classification of B1 or higher as required by the design.
Use materials complying with AS based on the Whole of Life approach to materials selection.
Do not use breccia or dolerite in concrete mixes.
Fly ash is a manufacturing bi-product that can be used as a cement replacement but should limited to a maximum of 20% by weight of cement content.
Unless otherwise specified the maximum permissible drying shrinkage shall be as follows:
F'c (MPa) Shrinkage (microstrain)
10, 15, 20 600
25,32,40, 45, 50 700
Prepare drawings for all steelworks, showing layout plans, framing elevations and sections and working details, so that normal Structural Steelwork shop drawings can be prepared and reviewed.
All bolts (except for purlins) are to be minimum M16-8.8/S. Use larger diameter bolts as the design requires. All bolts, nuts and washers are to be hot dipped galvanised. Holding down bolts may be black steel bolts if fully encased in concrete.
Unless the design dictates otherwise all bolt holes are to be 2mm larger in diameter than the bolt for a bolt not exceeding 24mm in diameter, and not more than 3mm larger for a bolt of greater diameter.
Bolt fixings of purlins are to be in accordance with manufacturer's details.
Do not hang any load from purlin flanges. Any suspender for ceilings & services etc. must be fixed to the web of purlins.
Provide additional purlins as required for supporting services etc.
All welds shall be shop welds. Site welding is not to be used, unless approved by the Principal.
Design all steelwork, especially beams and purlins, to ensure deflections are within acceptable limits.
Pay particular attention to:
Design steel support members, as required, to stabilise all window heads and sills and, where deemed necessary, the method of attachment of windows to such structure. Design similar members at other openings in walls.
For 15 years to first maintenance nominate corrosion protection for all structural steelwork whether external or internal, in accordance with the requirements of AS 2312 Guide to the protection of structural steel against atmospheric corrosion by the use of protective coatings. Protect internal steelwork as for external. Determine atmospheric environment/classification for the site from AS 2312.
If the Atmospheric Corrosivity Category is either C: Medium, D: High, or E: Very High, according to AS 2312 Clause 2.3, use a galvanised system for all exposed external steelwork and those elements which are not easily accessible for future maintenance (e.g. columns in a wall). Based on this system, use further coating mass in terms of galvanising or painting to comply with the 15 years guarantee requirement, as necessary.
Select member sizes and fabrication details which safeguard against warpage and distortion.
When selecting the protection system, ensure compatibility of the primer and top-coats. Do not use products containing lead or chrome bases.
Notwithstanding any other requirements, all cold-formed steel shall be zinc coated with a minimum coating mass of 300g/sq.m. Provide additional protection as the design requires.
Provide protection to steelwork directly in contact with the ground, by providing encased concrete protection or covering steelwork below ground level with tar epoxy paint.
Show clearly on the drawings any wall stabilising columns or other elements. Identify on the drawings any walls acting as lateral force resisting elements.
Suitably fix all brickwork/ blockwork to all columns and beams.
Show clearly on the drawings walls to be used as lateral bracing to steel columns and beam superstructure.
Give consideration to temporary bracing to steelwork until infill bracing walls are built.
The characteristic compressive strength of bricks used is to be 20 MPa minimum and mortar composition for new work shall be no leaner than 1:1:6. Where making good existing masonry, mortar strength should not exceed that of the adjacent masonry.
The characteristic compressive strength of concrete blocks used is to be 12 MPa minimum.
Show design data on the drawings.
Nominate materials complying with ASs. Do not use bush sand, silicone coated bricks or mortar admixtures.
Design brickwork to take into account the effects of dimensional changes due to variations in temperature, wetting and drying and long-term chemical changes associated with moisture.
The Characteristic Expansion em shall not exceed 0.8mm/m for which compliance certification is to be obtained from the brick supplier.
Determine the location of all joints in walls and show these clearly on the drawings. Provide joints at junctions of different materials.
Nominate masonry mesh reinforcement in bed joints in the courses below the top and above the bottom of walls, below and above openings, and at every fifth course. Lap reinforcement around corners. Refer to AS/NZS 2699 Built-In Components for masonry construction, Parts 1 and 2.
Design and document adequate drainage behind retaining walls at all levels where there is possibility of hydrostatic pressures being built up, unless the walls can cater for such pressures.
Provide capping to all blockwork walls exposed to weather to avoid water stagnation at the top.
Take into consideration the different movement characteristics of clay bricks and concrete blocks, if used in the same building.
Provide suitable corrosion protection for all metal items built into or in contact with masonry.
Steel products, including reinforcement, used in masonry shall have a corrosion resistance rating of not less than R2 as per AS 3700. Provide a higher rating as the design requires for the service conditions.
Include cavity ties or masonry veneer ties as appropriate to the service conditions and to the following minimum requirements;
Ties or anchors required to extend across control joints are to transfer the forces necessary to maintain the stability of the masonry without impairing the effectiveness of the joint. Similar performance is required for other ties such as those stabilising the top of walls.
Fixing of timber wall plates to masonry is to be by either straps or bolts.
Steel lintels are to be galvanised. Provide additional protective coating as the design requires.
All timber used is to be termite (white ant) resistant or treated to be termite resistant to the appropriate hazard level.
Drawings should be prepared for the structure and should:
Give careful consideration within the design to flexural deflection of timber members and trusses, both instantaneous and long term.
Design exposed bottom chords of roof trusses to carry a 1 kN hanging load at any position.
Where appropriate design roof trusses to also stabilise the tops of walls.
Provide corrosion protection for steel fasteners as specified in subsection STRUCTURAL STEELWORK of this Section.
Show clearly all member sizes and connections on the drawings.
Use cold-formed steel sections with a minimum zinc coating mass of 350 gm/sq.m.. Provide additional protection as the design requires to suit the service conditions.
The wall studs are to be laterally supported at the base and at the top to withstand wind pressures, earthquake loads and any other loads specified herein and as per the AS. Take special care in the design of the framing around openings, where extra structural members, for window sills, door/window heads, may be necessary for stability.
The framing deflections is to be limited to ensure compatibility with the finishes.
Design the walls to withstand possible impact by a 2 kN force applied at mid height.
Design for greater forces if these are envisaged.
Thickness of base metal of studs etc. is to be at least 0.75mm.