Podcast
Questions and Answers
What is a primary consequence of using gusset plates in trusses during a fire?
What is a primary consequence of using gusset plates in trusses during a fire?
- They allow for easier ventilation access.
- They strengthen the connections between trusses.
- They prevent fire from spreading inside wood.
- They contribute to the truss collapsing. (correct)
Which of the following best describes the impact of drilling holes into steel tubes and wood-chord trusses?
Which of the following best describes the impact of drilling holes into steel tubes and wood-chord trusses?
- It facilitates fire prevention measures.
- It improves the structural integrity of the wood.
- It allows fire to travel more easily through the chord. (correct)
- It enhances the aesthetic appeal of the construction.
What is the primary risk associated with cutting through trusses during ventilation?
What is the primary risk associated with cutting through trusses during ventilation?
- It can create openings for smoke to escape.
- It improves the overall safety of the structure.
- It might weaken the trusses and lead to failure. (correct)
- It ensures that the roof does not collapse.
What responsibility is placed on individuals who cut through any part of the truss system?
What responsibility is placed on individuals who cut through any part of the truss system?
What is a significant factor contributing to the vulnerability of trusses when sawing?
What is a significant factor contributing to the vulnerability of trusses when sawing?
What is a primary characteristic that makes flat timber trusses more dangerous than bowstring trusses?
What is a primary characteristic that makes flat timber trusses more dangerous than bowstring trusses?
What spacing is typically used for flat timber trusses?
What spacing is typically used for flat timber trusses?
Under what conditions should firefighters avoid working on or under flat timber trusses?
Under what conditions should firefighters avoid working on or under flat timber trusses?
What can occur as a result of the failure of one flat timber truss?
What can occur as a result of the failure of one flat timber truss?
What is critical for ensuring firefighter safety when dealing with flat timber trusses?
What is critical for ensuring firefighter safety when dealing with flat timber trusses?
What are the primary materials used in the most common truss design?
What are the primary materials used in the most common truss design?
Which component is primarily associated with connecting web members in truss designs that use steel?
Which component is primarily associated with connecting web members in truss designs that use steel?
What is a significant fire hazard associated with common truss designs?
What is a significant fire hazard associated with common truss designs?
What leads to the potential failure of a truss in a fire situation?
What leads to the potential failure of a truss in a fire situation?
Which describes the web members in a truss design that uses gusset plates?
Which describes the web members in a truss design that uses gusset plates?
What term did Professor Frank Brannigan use to describe the void spaces created by open-web trusses?
What term did Professor Frank Brannigan use to describe the void spaces created by open-web trusses?
What is a major concern associated with the void spaces in parallel-chord trusses?
What is a major concern associated with the void spaces in parallel-chord trusses?
Which type of trusses has been often used instead of solid joists for floor support?
Which type of trusses has been often used instead of solid joists for floor support?
What does the use of parallel-chord trusses instead of solid joists primarily address?
What does the use of parallel-chord trusses instead of solid joists primarily address?
What characteristic of steel affects its performance in a fire?
What characteristic of steel affects its performance in a fire?
What is a common feature of steel bar joists used in metal deck roofs?
What is a common feature of steel bar joists used in metal deck roofs?
What is a significant drawback of the design of steel bar joists?
What is a significant drawback of the design of steel bar joists?
How are the top and bottom chords of the steel bar joists typically formed?
How are the top and bottom chords of the steel bar joists typically formed?
Which of the following statements about the behavior of steel under fire conditions is true?
Which of the following statements about the behavior of steel under fire conditions is true?
What is the typical time frame for firefighters to search and attack before roof or floor sagging becomes noticeable?
What is the typical time frame for firefighters to search and attack before roof or floor sagging becomes noticeable?
What type of beam is particularly dangerous due to its potential sudden failure without noticeable sag?
What type of beam is particularly dangerous due to its potential sudden failure without noticeable sag?
Which component composition primarily makes up a plywood I-beam?
Which component composition primarily makes up a plywood I-beam?
What is a key concern regarding new lightweight structural systems mentioned in the content?
What is a key concern regarding new lightweight structural systems mentioned in the content?
What misleading assurance do marketers of plywood I-beams often provide to homeowners?
What misleading assurance do marketers of plywood I-beams often provide to homeowners?
What is the primary hazard for firefighters when cutting ventilation holes in roofs with metal decking?
What is the primary hazard for firefighters when cutting ventilation holes in roofs with metal decking?
What is the thickness of the average steel decking used in roofing, as mentioned?
What is the thickness of the average steel decking used in roofing, as mentioned?
Which insulating material can be used beneath the tar layer in this roofing system?
Which insulating material can be used beneath the tar layer in this roofing system?
What additional layer is laid over the insulation for waterproofing in this roofing system?
What additional layer is laid over the insulation for waterproofing in this roofing system?
What is the width of the steel sheets used for roof decking?
What is the width of the steel sheets used for roof decking?
What is a key difference in the behavior of steel joist-supported roofs compared to wooden trusses under fire conditions?
What is a key difference in the behavior of steel joist-supported roofs compared to wooden trusses under fire conditions?
How quickly do steel joist-supported roofs typically fail when exposed to heavy fire?
How quickly do steel joist-supported roofs typically fail when exposed to heavy fire?
What advance warning do firefighters receive when a steel joist-supported roof is under fire?
What advance warning do firefighters receive when a steel joist-supported roof is under fire?
What is the primary reason steel joists do not experience sudden failure in fire situations?
What is the primary reason steel joists do not experience sudden failure in fire situations?
In terms of firefighter safety, what advantage do steel joist-supported roofs provide during a fire?
In terms of firefighter safety, what advantage do steel joist-supported roofs provide during a fire?
What is a major risk for a firefighter when cutting a hole in a roof?
What is a major risk for a firefighter when cutting a hole in a roof?
What can happen if a firefighter inadvertently steps on unsupported metal decking?
What can happen if a firefighter inadvertently steps on unsupported metal decking?
Which factor increases the risk of a firefighter falling when making a cut in the roof?
Which factor increases the risk of a firefighter falling when making a cut in the roof?
What could lead to a firefighter being thrown off balance while cutting through a roof?
What could lead to a firefighter being thrown off balance while cutting through a roof?
Why is it critical for firefighters to know the positioning of joists before cutting?
Why is it critical for firefighters to know the positioning of joists before cutting?
What is the primary action that should be taken to ensure safety before a deck collapse occurs?
What is the primary action that should be taken to ensure safety before a deck collapse occurs?
Why is it important to cool steel during a fire?
Why is it important to cool steel during a fire?
What technique should firefighters employ when operating a hoseline during a deck fire?
What technique should firefighters employ when operating a hoseline during a deck fire?
What should firefighters do after knocking down the fire?
What should firefighters do after knocking down the fire?
What is a risk associated with firefighters not being able to see a collapsing roof?
What is a risk associated with firefighters not being able to see a collapsing roof?
Gusset plates penetrate the wood only ___ of an inch
Gusset plates penetrate the wood only ___ of an inch
Steel tube and wood chord trusses have a ____ in hole drilled into them for the pin
Steel tube and wood chord trusses have a ____ in hole drilled into them for the pin
Frank brannigan coined the term ____ loft
Frank brannigan coined the term ____ loft
Steel bar joist may be __ ft long and spaced up to __ ft apart
Steel bar joist may be __ ft long and spaced up to __ ft apart
Flashcards
Flat Timber Truss Construction
Flat Timber Truss Construction
Using 2x8/10s for chords and 2x4/6s for web members, spaced approximately 20 feet apart.
Flat Truss Collapse Hazard
Flat Truss Collapse Hazard
Spaced trusses can create wide gaps upon collapse, potentially of up to 40 feet.
Flat Truss Fire Safety Risk
Flat Truss Fire Safety Risk
Flat roofs resembling standard roofs, make them a disguise for fire risks, requiring careful preplanning before approaching the roof.
Truss Failure Chain Reaction
Truss Failure Chain Reaction
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High-Risk Truss Types
High-Risk Truss Types
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Truss Design: Gusset Plates
Truss Design: Gusset Plates
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Truss Design: Tubular Steel
Truss Design: Tubular Steel
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Lightweight Truss Materials Vulnerability
Lightweight Truss Materials Vulnerability
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Truss Fire Spread Mechanisms
Truss Fire Spread Mechanisms
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Truss Loft Fire Spread
Truss Loft Fire Spread
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Older Structure Fire Safety
Older Structure Fire Safety
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Firefighter Response Time Constraint
Firefighter Response Time Constraint
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Modern Truss System Failure Speed
Modern Truss System Failure Speed
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Lightweight Steel Roof Systems
Lightweight Steel Roof Systems
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Steel's Fire Weakness
Steel's Fire Weakness
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Steel Bar Joist Length & Spacing
Steel Bar Joist Length & Spacing
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Steel Joist Fireproofing Issue
Steel Joist Fireproofing Issue
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Ventilation Hole Cutting Risks
Ventilation Hole Cutting Risks
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Metal Deck Support Risks
Metal Deck Support Risks
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Steel Joist Sag vs. Snap
Steel Joist Sag vs. Snap
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Steel Roof Hazard Time
Steel Roof Hazard Time
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Cooling Steel after Collapse
Cooling Steel after Collapse
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Evacuation Before Collapse
Evacuation Before Collapse
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Solid Stream Hose Strategy
Solid Stream Hose Strategy
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Study Notes
Flat Timber Trusses
- Constructed similarly to bowstring trusses using 2x8s or 2x10s for chords and 2x4s or 2x6s for web members.
- Spaced approximately 20 feet apart, can create a 40-foot wide hole upon collapse.
- Flat roof design disguises danger, resembling older standard flat roofs, posing risks to firefighters.
- Preplanning is crucial for safety; roofs should not be approached if heavy fire is present.
- Collapse can occur from one truss failure triggering others, leading to total structural failure.
- Both flat and bowstring trusses are high-risk; firefighters must adopt defensive positions immediately with heavy fires.
Truss Design Concerns
- Common designs include gusset plates (joined with metal fasteners), tubular steel webs, and sheet metal gusset plates.
- Lightweight materials and air spaces act as heat sinks, increasing fire vulnerability.
- A single 2x4 can burn through, compromising entire truss integrity.
- Gusset plates penetrate wood minimally, leading to truss collapse when fire damages surface.
- Drilling holes into trusses weakens connections and allows fire spread inside chord members.
- Power saws can accidentally penetrate top chords during operations, risking major structural issues.
Truss Loft and Fire Spread
- Truss lofts create large void spaces, promoting uncontrolled fire spread especially in parallel-chord trusses used for floor joists.
- Older structures with solid joists typically had the ceiling attached, reducing fire risk in comparison.
Firefighter Response Time
- Firefighters have 10-20 minutes to perform search and rescue before structural sagging becomes noticeable.
- Many modern truss systems can fail in under 10 minutes without visible signs of distress.
Lightweight Roof Hazards
- Open-web steel bar joists supporting corrugated steel decks are common in commercial buildings.
- Steel is noncombustible but weakens rapidly when heated, particularly in thinner forms.
- Steel bar joists are formed into a Z pattern; can be up to 60 feet long and spaced 6 feet apart.
- Lack of fireproofing and insulation means unprotected steel can fail quickly in a fire.
Cutting Risks for Firefighters
- Cutting ventilation holes presents risks due to unknown locations of joists below the deck.
- Firefighters may inadvertently step on unsupported metal deck, risking falls.
Structural Collapse Insights
- Steel joists typically sag before collapsing rather than snapping like wooden trusses, providing some warning.
- Experience indicates these roofs fail in under 5 minutes of heavy fire exposure.
Fire Safety During Deck Collapse
- Evacuate area before collapse; visibility may be impaired due to smoke.
- Use solid-stream hoselines to cool structures ahead of personnel.
- Proper cooling can restore steel strength and stability; caution is essential when advancing into compromised areas.
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