BC Ch. 12 Fire-Resistive Construction

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Questions and Answers

What is the primary benefit of fire-resistive construction?

It is easy to modify

It contributes fuel to a fire

It is the most resistant to collapse and does not contribute fuel to a fire (correct)

It is inexpensive to build

What are the two primary materials used in fire-resistive construction?

Steel and concrete (correct)

Brick and aluminum

Glass and rubber

Wood and plastic

What is concrete composed of?

Sand, water, and metal

Portland cement, water, and aggregates (correct)

Clay, lime, and straw

Plastic, rubber, and glass

What is the main weakness of concrete in construction?

It is weak in tensile strength and shear resistance Signup and view all the answers

What are Reinforcing Bars (Rebar) used for in concrete?

To enhance tensile strength Signup and view all the answers

What is Spalling in the context of concrete?

Loss of surface material when concrete is exposed to heat Signup and view all the answers

What is the primary reason for using fire-resistive construction in buildings?

To enhance occupants' safety during a fire Signup and view all the answers

Which of the following statements about concrete is accurate?

Concrete is susceptible to cracking under tensile stress Signup and view all the answers

What happens to steel when it is heated?

It expands, potentially pushing against structural elements Signup and view all the answers

How does the loss of roof structure affect wall stability?

It can lead to destabilization of walls Signup and view all the answers

What is the main reason for reinforcing concrete with steel?

To enhance its tensile strength Signup and view all the answers

What occurs as a result of interaction between concrete and heated steel during a fire?

Concrete could crack or spall due to steel expansion Signup and view all the answers

What is a key feature of Precast Concrete Panels?

They are produced off-site and then transported Signup and view all the answers

What defines Tilt-Up Construction?

Panels are cast on-site and lifted into place Signup and view all the answers

What risk does modifying buildings with concentrated fire loads pose?

It can introduce more combustible materials, increasing risks Signup and view all the answers

What happens to steel under high heat in Type I construction?

It elongates and may lead to buckling Signup and view all the answers

What should be the priority for firefighters when dealing with heated steel?

To apply water to cool the steel and reduce collapse risk Signup and view all the answers

At what critical temperature does steel begin to elongate significantly?

1000°F (538°C) Signup and view all the answers

What risk is associated with prefabricated metal buildings in fire situations?

They may contain insulation that worsens fire hazards Signup and view all the answers

What action should be taken if cooling steel becomes too dangerous during a fire?

Establish collapse zones and switch to defensive tactics Signup and view all the answers

What impact does inadequate code enforcement have on fire safety?

It may increase fire risks and liability for municipalities Signup and view all the answers

What led to the Skyline Plaza Towers collapse in 1973?

Removal of structural shoring Signup and view all the answers

What does the term 'Plastic Design' refer to in steel construction?

The redistribution of loads across the structure Signup and view all the answers

Why is pre-fire planning vital for firefighters in buildings with steel structures?

It aids in understanding fire resistance requirements Signup and view all the answers

What defines on-site concrete?

Concrete that is molded and cured in the location where it will remain Signup and view all the answers

What is the primary benefit of reinforced concrete?

It enhances the tensile strength of concrete Signup and view all the answers

Which of the following best describes prestressed concrete?

Concrete that uses tensioned steel tendons to offset tensile stresses Signup and view all the answers

What is the function of composite columns?

To balance compressive and tensile strengths with steel and concrete Signup and view all the answers

What is a significant fire resistance issue with reinforced concrete?

It decreases in strength upon exposure to fire due to spalling Signup and view all the answers

What purpose do temperature rods serve in concrete?

To prevent cracking caused by temperature fluctuations Signup and view all the answers

What occurs to concrete at temperatures exceeding 572°F (300°C)?

It evaporates moisture, risking structural integrity Signup and view all the answers

What is the purpose of fireproofing in steel structures?

To maintain the integrity of steel during fires Signup and view all the answers

How is encasement used as a fireproofing method?

By enclosing steel with materials such as concrete or gypsum board Signup and view all the answers

What can lead to the failure of post-tensioned concrete during a fire?

Loss of tension at 800°F (427°C) Signup and view all the answers

What is the function of dynamic fire protection?

To cool steel using sprinkler systems during fire events Signup and view all the answers

What is classified as passive fire protection?

Applying fireproof coatings directly onto structural materials Signup and view all the answers

What advantages arise from combining passive and dynamic fire protection systems?

It creates a comprehensive defense against fire threats Signup and view all the answers

What is the role of concrete cover in fire-resistant design?

It protects reinforcement steel by delaying strength loss Signup and view all the answers

What causes spalling in concrete?

Moisture expanding within concrete when heated Signup and view all the answers

Study Notes

Fire-Resistive Construction

The primary benefit of fire-resistive construction is its high resistance to collapse and lack of fuel contribution during a fire.
Key materials in fire-resistive construction include steel and concrete, known for their strength.

Concrete Composition and Properties

Concrete is made from Portland cement, water, and aggregates.
It exhibits weakness in tensile strength and shear resistance, despite being strong in compression.

Reinforcement Techniques

Reinforcing bars (rebar) are used to enhance the tensile strength of concrete structures.
Spalling refers to the loss of surface material from concrete when exposed to heat.

Types of Concrete

Cast-in-place concrete is molded and cured at its final location.
Prestressed concrete utilizes tensioned steel tendons to offset tensile stresses, improving structural performance.

Column Design

Composite columns combine steel and concrete to optimize compressive and tensile strengths.
Fire resistance concerns for reinforced concrete include potential damage from spalling and heating of steel reinforcements.

Temperature Effects

Temperature rods are incorporated to resist cracking due to thermal changes.
Exposure to high temperatures (above 572°F or 300°C) can lead to evaporation of moisture, causing structural weaknesses.

Fireproofing Techniques

Fireproofing of steel structures is critical to maintain their integrity during fires.
Encasement involves covering steel with protective materials like concrete or gypsum board to enhance fire resistance.

Fire Protection Systems

Dynamic fire protection uses sprinkler systems to cool steel during a fire.
Passive fire protection utilizes fireproof coatings directly on steel for protection.

Concrete Fire Resistance

Concrete, recognized for its mass and density, effectively resists fire spread, making it an excellent material for fire-resistive design.
Concrete cover in fire-resistant design protects reinforcement steel and delays loss of strength during exposure to fire.

Risks and Structural Interaction

Unprotected steel is vulnerable to fire, posing a risk of structural collapse.
Tower cranes may shift out of plumb when exposed to heat, compromising structural stability.

Structural Dynamics in Fire

Thermal expansion of steel can lead to buckling or twisting of structural elements under high heat.
Loss of roof structure can destabilize walls, particularly in tilt-up construction.

Precast and Tilt-Up Construction

Precast concrete panels are manufactured off-site and transported to the construction site for quick installation.
Tilt-up construction involves casting concrete panels on-site and lifting them into place.

Building Modifications and Fire Loads

Modifications that introduce combustible materials can significantly increase fire risks.
Fire behavior in type I construction may result in steel elongation under heat, affecting structural integrity.

Firefighter Safety and Procedures

Firefighters should apply water to cooled steel to prevent structural collapse during active fires.
Establishing collapse zones is essential when cooling steel is too hazardous.

Regulatory and Historical Context

Inadequate code enforcement can lead to increased fire risks and potential liability for municipalities.
The Skyline Plaza Towers collapse in 1973 was a result of the removal of shoring, leading to a progressive failure.

Steel Construction Concepts

"Plastic design" in steel construction refers to the redistribution of loads across the structure, allowing for lighter materials.
Pre-fire planning is essential for firefighters to formulate effective strategies tailored to fire resistance requirements of buildings.

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Description

Test your knowledge on fire-resistive construction with this quiz. It contains 40 multiple-choice questions focusing on the benefits, materials, and principles of effective fire-resistant building techniques.