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.

Outline

Introduction

Farm Building Code

Fire Safety

Lateral Bracing

Truss Bracing

Concrete Issues

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

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 Separation

Firewalls to separate areas.

Maintain 4800 m2 maximum floor area

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

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

Knee Braced Building

Lateral Bracing

Diaphragm Roof

Lateral Bracing

Shear Wall Bracing

Lateral Bracing

Wind Posts and Buttress

Lateral Bracing

Wall Bracing

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

Sample Truss Layout

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.

Sample Truss Drawings

Truss Geometry

Truss Design

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.

Sample – Inadequate Bracing

Inadequate Bracing – What Happens

Collapse During Construction

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.

Bracing Requirements

Wood Members in Compression

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

A23.1 Table 4

Air Entrainment

Type 1 – 5-8% (14-20mm)

Type 2 – 4-7%

Design and Construction of Farm

Buildings

Questions