Building Fire Resistance and Classifications

Building Classification and Structural Fire Resistance

• Fire behavior is influenced by building and occupancy classification, fire and fuel load, and fire resistance.
• The International Building Code (IBC) classifies structures based on the materials utilized in their construction.
• The IBC uses 3-digit number codes signifying bearing walls, structural frames/columns, and floor construction (e.g., 4-4-3).
• There are 5 main classifications of building construction types.
• Type 4 is the only construction type without subclasses.

Type 1 Construction

• Building Type 1 is classified as Fire Resistive.
• Walls, columns, and beams must have a fire rating of 2–4 hours.
• Floors must have a fire rating of 2–3 hours.
• Roof decks and supports must have a fire rating of 1–2 hours.
• Interior partitions usually require a fire rating of 1–2 hours.
• Protected steel frame or reinforced concrete are features of Type 1.
• Fire ratings can be achieved by adjusting the thickness of the insulating material.
• Based on code, fire-retardant wood is allowed in roofs or interior partitions.
• Steel in Type 1 construction is noncombustible but may not be fire-resistive.
• Type 1 structures are less prone to collapse.
• Combustible materials are only allowed for cosmetic purposes in Type 1 structures.

Type 2 Construction

• Building Type 2 is classified as Noncombustible or protected noncombustible.
• The use of glass and aluminum is permitted, though with a limited structural role within Type 2 construction.
• Fire-resistive ratings can be omitted if the roof is 20 feet or more above the floor in Type 2 structures.
• Type 2A construction has protected structural components with a 1-hour fire resistance rating.
• Type 2B construction is unprotected, PLAN B is for baby, and unprotected steel is its most common characteristic.
• The failure rate of unprotected steel members in Type 2 depends on ceiling height, the size of unprotected members, and intensity of fire.

Type 3 Construction

• Building Type 3 is classified as ordinary construction with exterior masonry walls.
• Type 3 has two classifications of protected or unprotected interior structural components.
• Type 3A is 2-1-1, which means plaster gypsum board.
• Type 3B is 2-0-0, meaning unprotected steel.
• Type 3 utilizes 2x10 floor joists.
• Type 3 structures must have appropriate fire stops in combustible concealed spaces.
• Type 3 exterior masonry walls will collapse without interior support.

Type 4 Construction

• Building Type 4 is classified as Heavy Timber or "mill construction."
• Unlike other types does not use subclassifications.
• The designation 2HH is used in Type 4 instead of a subclass.
• Exterior walls are usually masonry, like Type 3.
• Type 4 uses solid or laminated wood with larger dimensions than Type 3.
• Concealed spaces are not permitted in Type 4 construction.
• Type 4 has minimum floor construction of 6x10 inches, which is thicker than Types 3 and 5.
• Type 4 is not normally used in new multistory buildings.
• Type 4 is commonly seen in old factories, mills, and warehouses.
• Type 4 is dangerous, contains relatively large amounts of fuel in structural supports.

Type 5 Construction

• In Type 5 Wood Frame construction, all major structural components are allowed to be of combustible construction.
• Type 5 must have 1-hour fire resistance for structural components.
• Type 5 has extensive concealed spaces.
• Type 5 is also known as "light frame" construction, and is common in North American residential and commercial buildings.
• Type 5 poses an extreme danger to adjacent structures if a fire occurs due to exposure threat.
• IBC limits the heights of Type 5 structures due to exposure threats.

Occupancy Classifications

• The IBC has 10 occupancy classes.
• NFPA 101 has 12 occupancy classes.
• NFPA 101 is the life safety code.
• Mixed occupancies necessitate a 1–4 hour fire-rated fire wall.

Fuel Load and Fire Resistance

• Fuel load refers to the total quantity of combustible materials in a compartment.
• Fuel load contributes to fire load: the maximum potential heat released if all fuel is consumed.
• Fire load is the product of the weight of combustibles times their heat of combustion, expressed in pounds per square foot.
• Fire load can estimate a building's total heat release rate (HRR) or thermal energy if fully involved in fire.
• The faster available fuel burns, the greater the HRR.
• Noncombustible materials will not ignite, burn, support combustion, or release flammable vapors when exposed to fire or heat under anticipated conditions.
• ASTM E 136 is the most common combustibility test.
• Fire resistance is the ability of structural assemblies to maintain load-bearing capacity and structural integrity during fire.
• Fire-resistive rating (FRR) measures fire resistance.
• FRR is expressed in time, using hours and fractions of hours.
• Exit stairwell walls, whether load-bearing or not, have lower fire resistance ratings than columns and floors.
• Fire resistance is commonly determined through laboratory testing.
• ASTM E-119 is the standard fire-resistance test method.
• Fire testing first occurred in Germany (1884–1886), and then in Denver, Colorado (1890) and New York City (1896).

Structural Design Basics

• Force is any interaction that can alter an object's motion.
• Load describes any effect a structure must resist.
• Stresses work against an apparatus', equipment's or structural support's strength.
• Reactions (R) resist applied loads.
• Equilibrium determines loads.
• Gravity is the most common load imposed on a structure via the weight of the structure's components.
• Other forces include vibrations, temperature, and shrinkage.
• Bending reaction within a structural component that opposes a vertical load.

Types of Stress

• Tension pulls apart, compression squeezes together and shear slides one plane of material past another.
• Axial load applies force to the center of an object.
• Eccentric load applies force perpendicular to an object's cross section.
• Torsional load applies force off-center on an object.
• Stress indicators include cracking, crumbling, bending, or breaking.

Types of load

• Dead loads are fixed and quantifiable while live loads are not fixed and permanent and static load is steady or gradually applied; dead loads are typically static.
• Static means "still".
• Dynamic loads involve motion, delivering energy beyond the weight of the object, such as wind or falling objects.
• Kinetic energy must be absorbed to stop a dynamic load's motion.
• Concentrated loads produce highly localized and non-uniform forces in supporting members.
• Rain and snow are live loads.
• Water from firefighting adds additional live loads such as the dynamic load of fire hoses and static load of accumulated water.
• Older multistory industrial buildings use scuppers to drain water.
• 250 gallons per minute may impact a target with 2,080 pounds of water per minute.
• 3 inches of water adds a static load of 21 pounds/square foot.
• Water in high-rises drains through elevator shafts and stairwells.
• Wind loads can exert direct pressure as straight-line winds.
• "Drag" describes wind flowing around an object.
• Negative pressure creates a suction effect on the downwind side.
• Rocking causes a building to sway.
• Vibration occurs as wind passes over a surface.
• "Clean off" describes wind dislodging or moving objects.
• Direct pressure is the primary consideration for wind loads.

Structural Components

• In beams, the top flange experiences compressive stresses, while the bottom flange experiences tensile stresses.
• Stresses are zero in the web, which is the beam's neutral axis.
• The top and bottom flanges carry most of the load resisting the beam's stresses.
• Tall beams can support greater loads.
• Columns are designed to support axial loads and are not built to endure bending stresses.
• Buckling can cause tall, thin columns to fail.
• Short squat columns may fail by crushing.
• Arches withstand primarily compressive interior stresses, producing inclined forces with occasional hinges.
• Cables, used over long spans, curve and experience tension stresses.
• Aluminum cables are lighter than steel.
• Trusses consist of triangles in one plane.
• True trusses are only made of straight members.
• Chords are the top and bottom members of a truss.
• Typical trusses span 22–70 feet; modern trusses can exceed 100 feet.
• Bar joists are lightweight steel trusses.
• Gusset plates join/strengthen separate components.
• Space frames are three-dimensional truss structures.
• Load-bearing walls carry compressive loads.
• Frame walls, which only provide lateral stiffness, are the skin.
• Studs are placed 12–16 inches apart.
• Stud walls use 2x4 inch wood studs.
• Post and beam construction carries traverse loads; vertical elements support horizontal elements, with diagonal braces for lateral loads.
• Transverse loads exert force perpendicular to structural members.
• 6x8 inch lumber is used when supporting roofs only.
• Rigid frames are typically single story with a gabled roof.
• Rigid frames transmit bending stress through joints.
• Hinged rigid frame roofs allow slight movement.
• Joints are the last part of a rigid assembly to fail under fire conditions.
• Slab and column frames are made of concrete drop panels, and a capital.
• Capital is a broad top surface of column/pilaster.
• Drop panels increase floor thickness.
• Membrane structures resemble fabric tents but are for permanent structures which lasts over 180 days
• PTFE strands are used for polytetrafluoroethylene.
• Fabric in membrane structures weighs less than 2 pounds per square foot.
• Shell structures are three-dimensional with thin components like concrete cones, domes, barrel vaults, and folded plates.

Building Systems: Stairs

• Stairs that are convenience are not part of egress and usually only have 2 levels.
• Stairways that are 4 stories or more may require one stairway that extends to the roof.
• Stair treads are also called the run, and risers are also called the rise .
• There are 6 common types of stairs.
• Straight-run stairs go directly from one level to another.
• Return stairs contain a landing between floors, which reverses the direction of travel.
• Scissor stairs are two separate stairs occupying the same shaft, offer space efficiency and reduced construction costs.
• Circular stairs, referred to as grand stairs or convenience stairs, must have a run width of at least 10 inches.
• Folding stairs are ladders, often found in attics/residential buildings, with limited capacity.
• Spiral stairs have tapered treads, often used for egress within residences or confined spaces.
• Protected stairs must be able to resist the effects of combustion.
• Exterior stairs are naturally ventilated with at least 1 open side with fully enclosed, exterior stairs subject to regulations similar to those of enclosed stairs.
• New construction has not permitted fire escapes for decades.
• Smokeproof stair enclosures limit fire penetration, and are minimally required for buildings with 5 or more stories.
• Smokeproof stair enclosures are located on the building perimeter, and can be entered through ventilated vestibules or open exterior balconies.
• Active smokeproof systems pressurize the enclosure upon fire alarm activation.
• Passive smokeproof systems provide smoke ventilation before it enters the stairwell.
• Open stairs connect no more than 2 adjacent floors above a basement level.
• Conveyors are used to transport items and materials.
• Escalator motors are located at the upper landing; the standard speed is 100 feet per minute but old escalators may reach 90-120 feet per minute and are linked with a 'step chain'.
• Escalators with 2+ floors have sprinklers, draft stops, or rolling shutters that have an 18-inch draft stop.
• Elevators recall and open at the floor level above to check the shaft for smoke.
• Elevator types include passenger, freight and service. Freight elevators are larger.
• Two common types of elevator power sources are hydraulic and electric.
• Hydraulic elevators are limited to 6 floors and do not use breaks, and are attached to a ram, multi stage cylinder.
• Manual lowering valves may be required on all electrical traction elevators.
• Hydraulic vehicles lack side or horizontal egress.
• Electric elevators have steel belts of cable and drum or flat polyethylene.
• Drum elevators transport passengers, have counterweights, and are found in old buildings and are obsolete..
• Traction elevators transport passengers and rise over 6 stories, fast with no maximum height and use counterweights, at 500 VAC or DC and the brake located on the drive motor shaft.
• The electrical traction elevator requires a top side exit, AC will brake to stop the car directly and DC the brakes do not play a stopping or parking part.
• Dumbwaiters transport cargo, use electric motors, and common in restaurants, schools, hospitals, and retirement homes.
• Machine room less elevators are used for smaller buildings.

Elevator Safety Features

• Elevator safety includes a terminal device to shuts off the power.
• Buffers act as pit shock absorbers.
• A speed-reducing switch and overspeed switch.
• Car safety jaws wedge against the guide rail to stop a free-falling car.
• Hoistways should be constructed of fire-resistant materials with fire-rated doors and have 1 to 2 hour fire ratings and enclosed on 3 sides with poured concrete.
• Elevator shafts used as egress means need safety lights/fire ratings appropriate for the structure's height.
• Vents are located at the top to prevent mushrooming.
• Three or less elevators can be in a single hoistway.
• Four or more elevators need a minimum of two separate hoistways.
• Four elevators are permitted per hoistway.
• Express elevators serve the upper floors (15–20 levels at a time).
• Upper floor landings have no stops, no top floors was a old test question.
• Rescue doors are placed every three floors.
• Double-decker elevators with even stopping levels for the top level will stop at odd floors.
• The vane strikes rollers, holding elevator/hoistway doors open.
• Passenger elevators- car doors have an electric motor.
• Electric interlocks stop car automatically when doors are open or activated and require electrical interlocks laterally/horizontally.
• Door clutches car door push paddle, big paddle on inside door we see in Door clutch car door push paddle, big paddle on inside door we see.
• Refuse chutes need sprinklers at the top and bottom.
• HVAC systems create comfortable environments, and becoming life-support systems in complex buildings.
• Cupolas for ventilation and lighting create vertical cooling and airflow.
• HVAC fans exceeding 2,000 cfm have separate supply and exhaust fans needing duct detectors.
• Butane and propane in HVAC are hazards for firefighters.
• Smoke dampers activated by the fire alarm system.
• Forced air systems need a 1-hour fire resistive enclosure in buildings less than 4 stories or 2 hour fire resistive in those with 4 or more.
• Hydronic systems with water as the heat transfer medium have cooling towers.
• Hurricane glazing on glass is difficult to ventilate and remove.
• To prevent recirculation, HVAC may be placed in Smoke Control Mode manually which takes priority or automatically through the Firefighters Smoke Control Station.
• Pressure sandwich systems supply air to non-fire floors to create a "pressure sandwich:" of higher air pressure above and underneath fire floors, reducing smoke movement.
• Theater stages need smoke vents.
• Vents with single/double leaf metal doors or plastic domes are must open at least a minimum of 4 feet.
• Vents aren't effective with sprinklers.
• Smoke towers, as smokeproof enclosures, are escape stairways with direct exit to a public way.
• Curtain boards need to measure at least 20% of the ceiling height.
• Draft curtains should be spaced no more than 8 times the ceiling height apart, pressuring staircases with either single or multiple fan injection system
• Transformers convert high voltage into step down or step up and into appropriate voltages mainly using in medium/large buildings at 3 phase 208/120 Volt.
• Vault rooms with sprinklers have a 1-hour fire rating and with none a 3 hour fire rating.
• Transformers generate heat so protect them with sprinklers or cool them via air/oil near or at grade with oil requiring dielectric, labeling and PCB properties and no air are dry.
• Generators must have 2-4 hours hospitals needing at least 48, and can only be 60 gallons.

Interior Finishes and Passive Fire Protection

• Materials in exposed walls and ceilings must not more than 10% and be tested by a flame spread.
• Surface Burning Characteristics degrees and measured rates determine fuel.
• International building codes doesn't include reference more than 1mm wide.
• Intumescent coatings expand upon exposure to heat.
• Mastics bond w/ most and heat surfaces using non-combustible adhesives.
• Specific square ft ratio application, protects assembly from the occupancy.
• Rated fire assemblies have a specific refuse/defending area.
• Firewalls foundation and roofs is their extensions into the building.
• Fire partitions in the building need subdivisions.
• Fire flow is required amount of water.
• Freestanding walls found 3 floors can help resist lateral load of 5 psf.
• Constructed steel columns have 1-4hr fire resistance.
• Combustible material must be 4ft. framed w/ concrete.
• Auto sprinklers eliminates walls.
• Fire resistive enclosure, fire rating buildings below 4 stories- 1-2hrs or above has 4 hrs.
• Curtain is a bearing type with concrete and is attached on the outside and gaps between the structure.

Fire Doors

• Fire rated walls have rates of increases every 20 minutes to 4 hours.

• A and B ratings are mainly coridors/smoke area.

• Class A- Opening in fire walls.

• Class B- Openings in vertical shafts in 2 hour rated partitions.

• Class C- Opening between rooms and corridors rating less than 1 hour.

• Class D- Openings in exterior walls subject to severe fire expose from the outside of a building

• Class E- Opening in exterior walls subject to moderate or light exposure from the outside

• Higher walls above 2 hours have 3-4 hr ratings with greater/1hr rating.

• There are 4 styles being: rolling or overhead cannot be egress, horizzontle/swinging/motorized use hardwares/hingeds must measure every 30i.

• Door held to alarm at 3hrs.

• Self-closing can prevent a light w/ wiremesh(wired) of 100sq. and 3 or of less total.

• Louvers in doors can have links but don't apply to doors.

Foundations

• Soil is the main influence to the foundation.
• Bedrock will support sign weights in sandy clay.
• Stratum is rock sheet.
• Soil testing is borings that go up to 8ft.
• Shallow foundation is based to reinforce with soil.
• A floating foundation has heavy concrete for deep support.
• Walls are to be wider at footing on columns is square pad.
• Deep pier or piles provide a footing system that drives below through friction (belled),water/caisson sleeve.
• Most walls connect with mortar due EPS, settlement is movements.
• Weigh one story's SOIL equals 5-8 stories in a building.

Wood Construction

• Lumber dimensions vary 8–24 feet, in nominal that are 1 1/2 x 3 1/2 for example 2x4.
• Solid wood 700 PSI, moisture is to 19% or less measured as gravity.
• Engineered has quick unpredictable unbonding issues where unprotected and has more glue.
• Laminated is more wood and joints have no support unless Glulam (heavy timber and fire effects with curves).
• Thickness measure 3/4 to 2 inches w/ depths of 3-75 inches (finger to scarf to matting.
• Structal wood/SCL with LVL the Strongest are long to bond w/ long resin.
• Composite is weather resist with 80 class and swells when glued.
• Panels insulates w/ foam and is protected by sip .
• Studs are a 2x2 w plates as a fire spread with sub-areas outside with a vapor system.
• Spray foam insulation is used but effects walls depeding surface spaces wjere the veneers has tied space of 20ft or increases w/ the floor heights while the roofs are grade and ignition at 392 starts pyrolysis for BTU combustion with 20B extinguisher and char combustion.
• Joist reduces w/ fire and the ballon is on ledge are light with the same construction codes as beams/trusses with steel gussets in rare with mortising.
• Collapse in wood usually is vulnerable to insects/ decay..

Masonry and Ordinary Construction

• The key to masonry is durability not tension.
• Masonry is weakest at the joints around 2500 PSI strength made of cement/water and 8 high in 4-100 process, cmus expand and stress so walls must be width.
• Cavity/header walls have pilots to have slight angles (CUT ****** END) protected with lentils for brackets.
• Parapets must rise equal to to roof with the false being a front.
• Wind pushes horizontal forces joints at a points while turn buckles must resist between.
• The main spread wall structure must resist.

Steel Construction

• Steel beams are used in fire but there must be less steed.
• Main is are iron/carbon and they react of 2200 when rolled to tested levels of PSI.
• It expends during heat even 20 FT and is well conductor at 490 pounds .
• Fire weaken it must be over 1200 w/ greater stress and must have protective concrete w/ mineral spray and steel/concrete is 1 to 4 hours rated but needs heat sunk and not to ignite when 1/4 used or tested when installed tested 2x4.
• High is fire w/ knee.

Floor

• Concrete ( 2 inches min light w/ 6-12) and steel cannot have more than 20 FT rating the connection and Gusset must resists on knees.

• The formed products are Coarse that measure more and with 500-6000psi w/ additives.

• Reinforce rebar as mech vibrators.

• Tee re force so do not cut tension cables even 1 ft unless pre formed and set. These are all used in secure.

• Steel must have batch for the ft for spalling, heat sinks , and supports .

• Garages have steel and 120 length in two where they use 1 pst.

Roofs

• It has cover, slope (low medium pitch). With 12/12 ratio at max of 19 degrees like to shed as hip or gambreks or deck and butter which are are 8 x 8 to give the best light.
• Archers need keel stones are use lamella .
• Can omit supports but has to be greater . _ Wood can be put if wood framing at in 24 and then can gypsum.
• No cast unless water has a membrane with the proper materials/
• Aluminum must tested be tested by a separated/ or A/B/C and should NOT have less than 4 degrees and is rain resistance with sky lights of no soil.
• It should be at 75 and has stair case
• Each zone has controls of heat.
• One should have no smoke to access the outside the bcs is must 20b exstingusher.

Special Structures

• Have at 75 foot have sprinklers must have more fire has access.
• To vent one must use pressure for the heat.
• There isn't a need level 5.

Each needs a space with controls and hydrant locations.

• Collapse has bolts only w/ seismic resistance that must resist and has land loss and code for wind so one must install wndow glazing to keep support and prevent collapse.