Current Issues and Concerns - Home - Ontario Building · PDF file · 2012-10-23of...
Transcript of Current Issues and Concerns - Home - Ontario Building · PDF file · 2012-10-23of...
Design and Construction
of Farm Buildings: Current Issues and Concerns
Ontario Building Officials Association Presentation by:
Annual Meeting and Technical Sessions Steven Adema, P.Eng
Sudbury, Ontario Director of Engineering, Principal
September 2012 Tacoma Engineers Inc.
Introduction
Tacoma Engineers
Tacoma Engineers has its roots in Guelph, Ontario where Jack Tacoma opened a sole proprietorship in 1980.
The firm has grown steadily to a staff of over thirty people, including professional engineers, project managers, technologists and administration staff.
We have been involved in the agricultural sector for over 25 years, and have proudly participated in the evolution of farm structures.
Contribute to scientific and technological advancements – advancements that require increased complexity, larger facilities, climate control and hygienic standards
Introduction
Canadian Farm Builders Association
Canadian Farm Builders was founded in 1980 by a small group of farm builders that saw a need for uniformity and quality control within the industry.
Mission Statement: CFBA promotes standards and builds awareness through communication, education and advocacy for the betterment of the farm building industry.
Over 225 professional members including: Builders; Building Officials; Governmental Agencies; Engineers & Designers; Material and Equipment Suppliers
Current efforts: Fire safety in large farm building; National Farm Building Code of Canada
National Farm Building Code
National Farm Building Code 1995 governs farm building construction in Ontario, BC and NS
No updates since publication
Old design criteria and material standards
AL, MB, SK, QC, NB, NL & PEI use no farm building code
Manitoba has issued a Farm Building Code in 2010
National Farm Building Code 1995
Part 3 NFBC – Fire Safety
Maximum Floor Area
4,800 m2 (51,650 ft2) for One Storey
2,400 m2 and 1,600 m2 for Two and Three Storey
Exceed the Area? Separate into Fire Compartments
Vertical Fire Separation with a 1 hour rating
Spatial Separation
30 metres from non-farm buildings and property lines
NO separation from adjacent farm buildings of low human occupancy
National Farm Building Code
The Canadian Commission on Building and Fire Codes has agreed to work on updating the requirements for large farm buildings with a view to incorporating these updates into the 2015 National Building and National Fire Codes. The new requirements will be objective-based to match the format of other reference documents.
NFBC Update
Recommendations have been submitted by the Joint Task Group on Farm Building Requirements.
Defining Small vs. Large Farm Buildings
3 storeys or less, building area not exceeding 600 m2
Small Farm Buildings – Prescriptive Code
Similar to Part 9, Small Buildings
Large Farm Buildings – Prescriptive / Performace
Classified Under Part 3, Fire Protection, Occupant Safety
Possibly create a new classification (3.2.2.x) to address the unique safety requirements for farm buildings
Fire Safety
Incidence of fires in farm buildings is increasing and the cost is growing at an alarming rate.
Large buildings are more difficult to extinguish unless enhanced fire fighting measures are included.
Majority of farm fires are deemed ‘preventable’. If standards were updated the extent of the fire damage could be significantly reduced.
Fire Safety
Ontario Dairy Farm: 100,000sf main barns plus
milk house and secondary areas (350,000sf gross)
NFBC – Farm Fires in Ontario
2004-2007
Fatalities - 0
Injuries - 17
Before
After
Year
2004
Fire Loss
$30M
2005 $25M
2006 $34M
2007 $57M
Fire Safety
Ontario Association of Fire Chiefs state that “NFBC may not adequately address the fire safety risks...due to the following factors”.
Size – building access and water supply
Combustibles – building materials, biogas, etc.
Appliances – equipment, hydro and fuel
Unrestricted Fire Spread – large open areas and inadequate fire separations
Ignition Sources – lighting and heating equipment
Use – classification of large Farm Buildings
Fire Safety
Building Access and Water Supply
Access roads on all sides
On-site water supply if no hydrants
Fire Safety
Spatial Separation
No requirements for farm building to farm building
11,000+ m2 of building
10m separation with 100% UPO
Fire Safety
Fire Stops – they do work
Continuity critical – doors, seal at steel deck
Perpendicular to trusses?
Fire Safety
OMAFRA & Ontario Technical Advisory Committee recently published “Reducing the Risk of Fire on Your Farm”.
Publication 837 examines the major causes of farm building fires and what can be done to reduce the risks.
Copies available through OMAFRA and Publication Ontario
Many images from this publication.
Fire Safety
OMAFRA & Ontario Technical Advisory Committee recently published “Reducing the Risk of Fire on Your Farm”.
Publication 837 examines the major causes of farm building fires and what can be done to reduce the risks.
Copies available through OMAFRA and Publication Ontario
Many images from this publication.
Lateral Bracing
Bracing provided to resist the lateral forces (wind) acting on the structure.
Two systems to consider:
Temporary bracing during construction
Permanent bracing
Lateral Bracing
Wind acts on structures
directly (positive pressure);
suction (negative pressure); and
uplift (negative pressure)
Need to consider overall stability and adequacy of sub-systems (trusses)
Open Sided Building – positive pressure on entire inside
of building + outside pressures
Large Openings in Farm Buildings
Lateral Bracing
Lateral Bracing
Overall Building Stability
Bracing options to address the building as a macro entity
Two basic options:
Knee braces
Diaphragm roof
Transfer loads to relatively stiff elements
Shear walls
Wind posts
Wall braces
Lateral Bracing
Truss Bracing
Trusses are very slender elements that require bracing for stability
Temporary bracing of trusses during erection and construction is specified by TPIC.
External bracing (to ground) for overall support
Internal bracing (truss to truss) for stability
Truss Bracing
Trusses have been used in construction for centuries as an efficient method of spanning large distances.
Innovation has played a large role in the development of trusses:
Origins - truss members were tied or nailed together
Progress - On-site construction with wood gusset plates
Today - Plant fabrication with steel plates dates from 1952
Widely used in residential, commercial and agricultural applications.
Truss Design
Engineering is the foundation of truss design.
Computers have allowed for detailed computation and experimentation with optimized geometry and member specification.
Increased efficiency has many benefits but also drawbacks.
Long spans with custom geometry
Material conservation
Slender and fragile until fully erected
Reduced redundancies
Truss Details
Detailed design drawings from the truss suppliers
Engineered drawings with all pertinent information outlined
Critical that all stakeholders review prior to fabrication to confirm geometry, loads, bearing conditions, bracing requirements and special instructions
Many formats provided but all should provide the same information.
Truss Erection and Bracing
Building bracing is equally important.
All permanent building bracing (lateral force resisting system) must be installed before temporary bracing is removed.
Typical single 2x6 diagonal strut braces at 20’ long are not adequate. Braces must be cross strapped and tied back to the main framing.
Collapses do occur and are very dangerous and costly.
Bracing Requirements
Lateral (horizontal) braces are installed to support the webs [design on truss drawings].
X-bracing is required to restrain the lateral braces installed [design by building engineer].
Designed with spacing to match the accumulated horizontal forces developed.
Typically installed ever 50’ and at each end of the structure.
Bracing Requirements
Permanent (or system) truss bracing is required to give structural integrity to the truss members.
Trusses use very slender elements that need support to realize their strength.
Large farm truss webs can have over 5000# of compression force which can lead to buckling.
Truss Bracing
Truss Bracing
Approximately 2% of the web load is transferred into a lateral force.
Series of braces provided to resist the accumulated forces. Spacing of the braces is a function of the brace design.
Concrete Issues
Raised by Bart Kanters, P.Eng., Director of Technical Services, Ready Mix Concrete Association of Ontario
What is required for Agricultural Concrete?
A23.1 Table 1
Classes of Concrete
Based on Location and Exposure
A2 – Reinforced, Exposed to Manure, with or without freeze thaw
A4 – Non-reinforced, Exposed to Manure, without freeze thaw
N – Plain, No Manure, No freeze thaw
A23.1 Table 2
Concrete Requirements
A2 – 32 MPa, Type 1 Air
A4 – 25 MPa, Type 2 Air
N – 25 MPa, no Air