PE Architectural flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Section modulus

S = I/c, the section property relating bending moment to stress. Required S equals moment divided by allowable stress; for a rectangular beam S = bd²/6, so capacity grows with depth squared.

Simple beam deflection

For a uniformly loaded simple beam, maximum deflection at midspan equals 5wL⁴ divided by 384EI. Because span appears to the fourth power, doubling span increases deflection sixteen times.

Tributary area

The floor or roof area whose load is carried by a single member. For an interior column it is the product of the two adjacent bay spacings.

Live load reduction

ASCE 7 allows reduced design live load on members with large tributary area using L = L0(0.25 + 15 divided by the square root of KLL times AT), with a floor of 50 percent for one-floor members.

Seismic base shear

Total lateral force at the base of a structure, computed as V = Cs times the effective seismic weight W, then distributed vertically over the building height for member design.

Allowable soil bearing

The soil pressure a footing may impose, commonly 2,000 to 4,000 psf for granular soils. Required footing area equals the column load divided by this allowable value.

Sensible heat equation

Qs in Btu per hour equals 1.08 times airflow in CFM times the dry-bulb temperature difference. Used to size coils and derive air quantity from a known temperature change.

Ton of refrigeration

A cooling rate of 12,000 Btu per hour, equivalent to melting one ton of ice in 24 hours. Equipment capacity for chillers and direct-expansion units is stated in tons.

Latent heat equation

QL equals 0.68 times CFM times the humidity ratio difference in grains per pound of dry air. It captures the moisture a cooling coil must remove from ventilation and internal gains.

Duct friction rate

Ducts are commonly sized at about 0.1 inch water gauge pressure drop per 100 feet of equivalent length. Higher friction rates shrink duct size but raise fan static pressure and noise.

Plumbing drain slope

Horizontal drains 3 inches and smaller slope at 1/4 inch per foot; 4-inch and larger drains may slope at 1/8 inch per foot, maintaining scouring velocity in larger pipe.

Ohm's law

Voltage equals current multiplied by resistance, expressed V = I times R. It underlies conductor sizing, voltage-drop calculations, and diagnosis of circuit faults.

Three-phase power

Power equals the square root of three times voltage times current times power factor. A balanced three-phase circuit delivers about 1.73 times the power of a single-phase circuit at the same amperage.

Voltage drop formula

For single-phase circuits, drop equals 2KIL divided by circular mils, with K near 12.9 for copper. Branch circuits should stay within 3 percent, feeders plus branch within 5 percent.

Electrical working clearance

NEC 110.26 requires a space 30 inches wide, 36 inches deep, and 6 feet 6 inches high in front of panelboards and switchboards, kept permanently clear of storage.

Continuous load factor

Circuits serving loads operating three hours or more must be sized at 125 percent of the continuous load plus 100 percent of the noncontinuous load, which is why a 20-amp breaker serves 16 amps.

Egress width per occupant

IBC capacity factors are 0.3 inch per occupant for stairways and 0.2 inch for other egress components; sprinklered buildings may use 0.2 and 0.15 inch respectively.

Occupant load factor

Floor area per person used to compute egress demand: business 150 gross square feet, classrooms 20 net, unconcentrated assembly 15 net, concentrated assembly 7 net.

Stair riser and tread

IBC limits risers to 7 inches maximum and treads to 11 inches minimum. Riser plus tread should total roughly 17 to 18 inches for a consistent, safe rhythm.

Two means of egress

Required where the occupant load reaches 50 or where common path or travel distance limits are exceeded. The two exits must be separated by a distance related to building diagonal.

Ramp slope limit

Maximum running slope for an accessible ramp is 1:12, or 8.33 percent. Landings are required at the top, bottom, and every 30 inches of rise, with 60-inch landings at turns.

Accessible clear width

Accessible routes require 36 inches minimum continuous clear width and 60-inch spaces for turning. Doors must provide 32 inches clear width when open 90 degrees.

Concrete 28-day strength

Specified compressive strength is measured on standard cylinders at 28 days; 4,000 psi is common for structural frames, and modulus of elasticity approximates 57,000 times the square root of f'c.

Steel thermal expansion

Steel expands about 6.5 times ten to the minus sixth per degree Fahrenheit, roughly 0.00065 inch per 100 feet per 10 degrees, so long buildings need expansion joints.

Type X gypsum board

Five-eighths-inch Type X gypsum board on steel studs provides about a one-hour fire rating. Additional layers or insulation increase the rating toward two hours.

Wood moisture content

Framing lumber should be dried to 19 percent moisture content or less before enclosure. Wood shrinks most in the tangential direction, causing flat members to lose width.

Mortar types

Type M is highest in compressive strength, Type S is the general structural choice, and Type N serves moderate exposure. Concrete masonry units are nominally 8 by 8 by 16 inches.

Critical path

The longest sequence of dependent activities through the schedule network. Its duration sets the project completion date, and activities on it have zero total float.

Total float

The time an activity can be delayed without delaying project completion, computed as late start minus early start or late finish minus early finish.

Retainage

A percentage, commonly 5 to 10 percent, withheld from each progress payment until substantial completion, protecting the owner against incomplete or defective work.

Change order

A written modification to contract scope, price, or time, signed by the owner and generally priced before work proceeds. It becomes part of the contract documents.

Performance bond

A surety instrument guaranteeing the contractor will complete the work per the contract. If the contractor defaults, the surety funds completion or pays the penal sum.