PE Construction flashcards

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

Work breakdown structure

A deliverable-oriented hierarchical decomposition of project scope. The lowest level is a work package that can be estimated, scheduled, and assigned to one responsible party.

Total float formula

Total float equals late start minus early start, or late finish minus early finish. It is the time an activity can slip without delaying the project completion date.

PERT expected duration

The PERT three-point estimate is (optimistic + 4 times most likely + pessimistic) divided by 6. Weighting the most likely value reduces bias in probabilistic scheduling.

Tremie concrete placement

Concrete is placed underwater through a vertical pipe whose discharge end stays submerged in fresh concrete, preventing water washout and segregation. The pipe stays full and is lifted slowly.

Sheepsfoot roller use

A sheepsfoot roller compacts cohesive soils such as clay and silt by kneading. It is most effective when the feet penetrate the lift and walk out as density increases.

Wellpoint dewatering

A wellpoint system uses a header pipe and closely spaced suction points to lower groundwater about 4 to 6 meters. Deeper drawdown requires staged or deep-well systems.

Effective stress principle

Effective stress equals total stress minus pore water pressure. It controls soil shear strength, compressibility, and consolidation settlement, forming the basis of Terzaghi soil mechanics.

Plasticity index

The plasticity index equals liquid limit minus plastic limit. It indicates the water content range over which soil behaves plastically; high values suggest expansive clay.

Darcy's law

Flow through soil equals hydraulic conductivity times hydraulic gradient times cross-sectional area (q = k i A). It describes laminar seepage and supports dewatering and stability analyses.

Simply supported beam moment

For a uniform load w over span L, maximum bending moment is wL squared over 8 at midspan, and maximum shear is wL over 2 at the supports.

Euler buckling load

Critical buckling load equals pi squared times EI divided by (KL) squared, where K depends on end conditions. Slender columns buckle before reaching yield stress.

Section modulus

Section modulus equals moment of inertia divided by distance to the extreme fiber. Bending stress in a beam is computed as moment divided by section modulus.

Rational method

Peak runoff Q equals runoff coefficient times rainfall intensity times drainage area (Q = CiA). Intensity is chosen for a storm duration equal to the time of concentration.

Manning's equation

Open-channel velocity equals 1.486/n times hydraulic radius to the two-thirds power times slope to the one-half power in US customary units. Discharge is velocity times area.

NRCS curve number

The curve number method estimates direct runoff from rainfall using hydrologic soil group, land use, and antecedent moisture. Runoff Q = (P - 0.2S) squared over (P + 0.8S).

Water-cement ratio

Lower water-cement ratio increases concrete strength, reduces permeability, and improves durability but reduces workability. Typical structural ratios range from 0.40 to 0.50.

Air entrainment

Entrained air bubbles, typically 4 to 8 percent by volume, provide freeze-thaw durability by relieving hydraulic pressure in saturated concrete. Air content increases as maximum aggregate size decreases.

Swell and shrinkage factors

Swell is the volume increase when bank soil is excavated and loosened. Shrinkage is the volume decrease when loose soil is compacted. Both convert bank, loose, and compacted quantities.

Horizontal directional drilling

A trenchless method that installs pipes and conduits beneath obstacles with minimal surface disturbance. Drilling fluid maintains borehole stability, and the method suits road and river crossings.

Concrete cold-weather protection

Fresh concrete must be maintained above 50 F until it reaches about 500 psi strength. Methods include heated water and aggregates, accelerators, insulating blankets, and heated enclosures.

Forward pass scheduling

The forward pass calculates early start and early finish for each activity by working from project start through the network, adding durations to the controlling predecessor finish.

Free float

Free float is the early start of the successor minus the early finish of the activity. It is the delay possible without affecting any successor early start.

Schedule crashing

Crashing shortens duration by adding resources to activities on the critical path. It increases cost and should target the lowest cost-per-day slope first.

Earned value CPI

Cost performance index equals earned value divided by actual cost. A CPI below 1.0 means the project is over budget relative to the work performed.

Estimate accuracy class

AACE estimate classes range from Class 5 conceptual at minus 30 to plus 50 percent accuracy to Class 1 definitive at minus 5 to plus 10 percent.

Schedule performance index

SPI equals earned value divided by planned value. Values below 1.0 indicate that work is progressing slower than the baseline schedule planned.

Differing site conditions

Type I latent conditions are hidden physical conditions differing materially from contract documents. Type II is an unknown physical condition of unusual nature. Both usually entitle the contractor to adjustment.

Performance bond

A surety bond guaranteeing the contractor will complete the work per contract terms. If the contractor defaults, the surety arranges completion or pays the owner the bond amount.

Substantial completion

The stage when work is sufficiently complete for its intended use, allowing owner occupancy. It starts warranty periods and limits assessment of liquidated damages.

Excavation protective system threshold

OSHA requires a protective system for excavations 5 feet or deeper unless a competent person determines no hazard exists. Shallower excavations also need protection when hazards are present.

Crane power line clearance

For overhead lines up to 50 kV, equipment must stay at least 10 feet away. Higher voltages require greater distances per the OSHA table, and a dedicated spotter is required.

Competent person definition

One who can identify existing and predictable hazards and has authority to take prompt corrective measures. Required for excavations, scaffolds, fall protection, and other high-hazard work.