PE Civil: Structural flashcards

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

Critical path

The longest continuous path through a project network; its activities have zero total float, so any delay on this path delays the entire project completion date.

Total float formula

Total float equals late start minus early start, or late finish minus early finish; it is the time an activity can be delayed without delaying project completion.

PERT expected duration

The PERT expected activity duration equals (optimistic + 4 times most likely + pessimistic) divided by six, weighting the most likely estimate most heavily.

Earned value cost variance

Cost variance equals earned value minus actual cost; a positive value indicates the project is under budget, while a negative value indicates over budget.

Addendum definition

A written modification to construction bid documents issued before bid opening; it becomes part of the contract documents and must be acknowledged by bidders.

Active earth pressure coefficient

For a cohesionless backfill, the Rankine active coefficient is Ka equals tangent squared of 45 degrees minus half the soil friction angle.

Wellpoint dewatering

A shallow dewatering system using a header pipe and risers with suction pumps to lower the groundwater table near an excavation, typically limited to about 15 to 20 feet.

OSHA spoil pile distance

OSHA excavation rules require excavated spoil and equipment to be kept at least two feet from the edge of the excavation to reduce surcharge and collapse risk.

Concrete free-fall limit

Concrete should not free-fall more than about five feet during placement; greater drops require a tremie or drop pipe to prevent segregation of aggregates.

Crane load chart

A crane's rated capacity decreases as operating radius and boom length increase; the load chart governs and rigging weight must be deducted from capacity.

Simple beam uniform moment

For a simply supported beam with a uniformly distributed load w over span L, the maximum bending moment is w times L squared divided by eight at midspan.

Cantilever end load deflection

For a cantilever of length L and stiffness EI with a point load P at its free end, maximum deflection is P L cubed divided by three EI.

Euler buckling load

The elastic critical buckling load of a column is pi squared times EI divided by the square of the effective length KL, where K depends on end conditions.

Shear moment relationship

The slope of the bending moment diagram equals the shear force at that section; the slope of the shear diagram equals the negative distributed load.

Degree of static indeterminacy

For a plane rigid frame, static indeterminacy equals three times the number of members plus reactions minus three times joints; a truss uses members plus reactions minus twice joints.

Torsion shear stress

In a circular shaft subject to torque T, the shear stress at radius c is T times c divided by the polar moment of inertia J.

Concrete modulus of elasticity

For normal-weight concrete, the modulus of elasticity in psi is approximately 57,000 times the square root of the specified 28-day compressive strength in psi.

A992 steel yield strength

ASTM A992 structural steel, commonly used for wide-flange shapes, has a minimum specified yield strength of 50 ksi and tensile strength of 65 ksi.

Modulus of rupture

The flexural tensile strength of normal-weight concrete is estimated as 7.5 times the square root of f-prime-c in psi for modulus of rupture.

Creep

Creep is time-dependent deformation of concrete under sustained stress; it increases with load duration, moisture loss, and higher stress levels, causing long-term deflection.

Steel Poisson's ratio

Poisson's ratio for structural steel is approximately 0.3, meaning lateral strain is about three-tenths of axial strain within the elastic range.

Standard bolt hole size

For standard holes in steel connections, the hole diameter is the bolt diameter plus one-sixteenth inch, providing normal erection tolerance.

Weld throat thickness

For a fillet weld, the effective throat thickness equals 0.707 times the leg size, which is used to compute weld shear strength.

Block shear failure

A connection failure mode combining tensile rupture on one plane and shear rupture on a perpendicular plane, governed by AISC block shear provisions.

Composite beam shear studs

Headed shear studs welded to a steel beam transfer horizontal shear between the steel and concrete slab, enabling composite action.

Slip-critical connection

A bolted steel connection in which high-strength bolts are pretensioned so that friction between plies prevents slip under service loads.

Eccentric connection

When a connection load acts at a distance from the bolt group or weld centroid, the resulting moment adds shear to fasteners and must be included in design.

LRFD basic load combination

The basic ASCE 7 strength load combination for gravity is 1.2 times dead load plus 1.6 times live load, used in LRFD design.

Seismic base shear

The seismic base shear is the seismic response coefficient Cs times the effective seismic weight W of the structure, per ASCE 7.

Wind velocity pressure

Velocity pressure in psf equals 0.00256 times Kz times Kzt times Kd times V squared, where V is basic wind speed in mph.

Retaining wall overturning FS

A common design criterion requires a factor of safety against overturning of at least 2.0 for retaining walls, resisting overturning moments from lateral earth pressure.

Diaphragm

A horizontal roof or floor system that collects and transfers lateral loads to vertical elements such as shear walls or frames.