Engineer Civil Engineering flashcards
Engineer Civil Engineering · Build recall with a focused review session.
32 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Absolute volume mix design
- Method that sums paste, fine aggregate, and coarse aggregate absolute volumes to 1 m³, then adjusts batch weights for aggregate moisture content before mixing.
- Total float
- Difference between late finish and early finish of an activity. It is the time an activity can slip without delaying the project completion date on the network.
- Modified Proctor test
- Compaction test using four or five layers and a heavier hammer, delivering about 4.5 times the energy of the standard Proctor test. Used for heavily loaded pavements and fills.
- Earned value CPI
- Cost Performance Index equals earned value divided by actual cost. A value below one indicates the work performed cost more than the budget allowed.
- Curing duration
- Minimum moist-curing period is typically seven days for Type I cement concrete and three days for Type III, counted from placement, to ensure strength and durability gain.
- Finish rolling temperature
- Asphalt compaction must be completed before the mix cools below about 85 degrees Celsius, when viscosity becomes too high for rollers to achieve specified density.
- Effective stress
- Total vertical stress minus pore water pressure at a point. It governs soil shear strength, settlement, and bearing capacity, unlike total stress in saturated soil.
- Terzaghi bearing capacity
- Ultimate bearing equation summing cohesion, surcharge, and unit weight terms with factors depending on friction angle. Shape factors modify the strip footing result for square and circular footings.
- Rankine active coefficient
- Ka equals tangent squared of forty-five degrees minus half the friction angle. It converts vertical effective stress to horizontal active earth pressure for a yielding wall.
- Degree of consolidation
- Ratio of settlement at a given time to ultimate settlement. Fifty percent consolidation occurs at a time factor of 0.197, ninety percent at about 0.848.
- Plasticity index
- Liquid limit minus plastic limit. A high index, often above thirty, indicates expansive clay with significant volume change potential under moisture variation.
- Liquefaction susceptibility
- Saturated loose uniform sands with corrected blow counts below fifteen and shallow groundwater are most susceptible to strength loss during earthquake shaking.
- Slope factor of safety
- Ratio of resisting to driving forces or moments on a potential failure surface. Permanent slopes usually require at least 1.5.
- Tension-controlled section
- Reinforced concrete section with tensile strain at least 0.005 at nominal strength, permitting a strength reduction factor of 0.90 for flexure.
- Whitney stress block
- Rectangular equivalent compressive stress of 0.85 f'c over depth a equal to beta-one times neutral axis depth, used to compute nominal flexural strength.
- Beta-one factor
- Factor reducing stress block depth for high-strength concrete. It is 0.85 up to 28 MPa and drops 0.05 per 7 MPa above, with a floor of 0.65.
- Minimum shear reinforcement
- Required when factored shear exceeds half the design concrete shear capacity. It prevents brittle failure and is provided as stirrups meeting minimum area and spacing rules.
- Euler buckling load
- Critical axial load equals pi squared times modulus times moment of inertia divided by effective length squared. Effective length factor depends on end restraint conditions.
- Compact section
- Steel section whose flange and web slenderness ratios are below the plastic limit, allowing the full plastic moment to develop before local buckling.
- Live load deflection limit
- Floor members are commonly limited to span divided by 360 under live load and span divided by 240 under total load to control cracking and vibration.
- Stopping sight distance
- Sum of distance traveled during perception-reaction time and braking distance. Braking distance depends on speed, friction, and grade.
- Superelevation equation
- Required rate relates speed squared divided by 127 times radius, minus side friction factor. Minimum radius follows from maximum superelevation and friction.
- Vertical curve K value
- Length of vertical curve divided by algebraic grade change in percent. Crest K values are governed by stopping sight distance, sag values by headlight distance.
- Greenshields model
- Linear speed-density relationship predicting zero flow at jam density and maximum flow at half free-flow speed and half jam density.
- Structural number
- Pavement design value summing layer thickness times layer coefficient and drainage modifier. It represents required structural capacity for traffic loads.
- Passenger car equivalent
- Factor converting heavy vehicles to equivalent passenger cars for capacity analysis. Trucks and buses reduce capacity on grades and in traffic streams.
- Rational method
- Peak runoff equals runoff coefficient times rainfall intensity times area. Intensity duration equals time of concentration. Suitable for small urban drainage areas.
- Manning equation
- Open channel velocity equals roughness reciprocal times hydraulic radius to the two-thirds power times slope to the one-half power. Flow is velocity times area.
- Curve number method
- Estimates direct runoff depth from rainfall using a curve number based on land use, soil group, and antecedent moisture. Higher numbers mean more runoff.
- CT disinfection value
- Product of disinfectant residual concentration and contact time. Required values rise with pH and fall with warmer water temperature for a given organism inactivation.
- Froude number
- Ratio of flow velocity to the square root of gravity times hydraulic depth. Below one is subcritical, above one supercritical, and one is critical flow.
- Water hardness
- Sum of calcium and magnesium concentrations expressed as calcium carbonate equivalent, computed as 2.5 times calcium plus 4.1 times magnesium in mg/L.