AMIE Section B Civil flashcards
AMIE Section B Civil · 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.
- Lever arm in RC beam
- The distance between the centroid of compressive force in concrete and tensile force in steel, equal to d minus 0.42 times the neutral axis depth xu.
- Under-reinforced section
- A reinforced concrete section in which steel yields before concrete crushes, giving ductile warning of failure; ensured by limiting xu/d to 0.48 for Fe415.
- Nominal shear stress
- Shear force divided by the product of beam width and effective depth; compared with design shear strength tc of concrete to decide whether stirrups are required.
- Terzaghi bearing capacity
- Ultimate soil pressure under a footing expressed as a sum of cohesion, surcharge, and unit-weight terms, each multiplied by a bearing capacity factor depending on friction angle.
- Plasticity index
- The numerical difference between liquid limit and plastic limit, indicating the range of water content over which a soil remains plastic.
- Liquid limit
- The water content at which soil changes from plastic to liquid behaviour, determined by the Casagrande cup or cone penetrometer test at 25 blows.
- Standard Proctor test
- A laboratory compaction test using a 2.6 kg rammer dropped 310 mm onto soil in three layers, giving the maximum dry density and optimum moisture content.
- Initial setting time
- The period from adding water to cement paste until it begins to stiffen and lose plasticity; must be at least 30 minutes for ordinary Portland cement.
- Le Chatelier test
- A soundness test measuring expansion of cement paste caused by free lime; expansion must not exceed 10 mm for ordinary Portland cement.
- Abrams' law
- The rule that concrete strength is inversely related to the water-cement ratio for a given set of materials and curing conditions.
- Slump test
- A workability test in which a standard cone of fresh concrete is lifted and the vertical settlement measured; typical values are 25 to 75 mm for normal reinforced concrete.
- Manning's equation
- An empirical formula for uniform open-channel velocity equalling one over roughness n, times hydraulic radius to the two-thirds power, times bed slope to the one-half power.
- Hydraulic radius
- The cross-sectional area of flow divided by the wetted perimeter; for a most efficient trapezoidal channel it equals half the flow depth.
- Most efficient channel section
- The channel geometry carrying maximum discharge for a given area and roughness; for a trapezoid this occurs when half the top width equals the side slope length.
- Rise and fall method
- A levelling reduction technique comparing consecutive staff readings to obtain rises or falls, then cumulatively adding them to the first reduced level.
- Prismoidal correction
- A volume adjustment subtracted from the trapezoidal end-area volume to account for curvature of the ground between cross-sections, improving earthwork accuracy.
- Effective depth
- The distance from the extreme compression fibre of a concrete section to the centroid of the tension reinforcement, used in flexural and shear design.
- Limit state of collapse
- A design criterion ensuring the structure resists bending, shear, compression, and torsion with adequate safety factors applied to loads and material strengths.
- Degree of saturation
- The ratio of volume of water to volume of voids in a soil mass, expressed as a percentage and ranging from zero for dry soil to 100 percent for saturated soil.
- Void ratio
- The ratio of volume of voids to volume of solids in a soil mass; for a typical dense sand it lies between 0.4 and 0.7.
- Coefficient of consolidation
- A parameter from the one-dimensional consolidation test describing the rate of pore pressure dissipation; determined from the time-settlement curve using the square root or log-time method.
- Effective stress
- Total stress minus pore water pressure in a saturated soil; it governs shear strength, compressibility, and settlement behaviour of the soil skeleton.
- Standard penetration test
- A field test driving a split spoon sampler 300 mm with a 63.5 kg hammer falling 750 mm, giving an N value correlated with soil density and friction angle.
- Active earth pressure
- The minimum lateral pressure exerted by soil when a retaining wall moves away from the backfill, given by Ka times vertical effective stress with Ka from Rankine theory.
- Critical hydraulic gradient
- The upward seepage gradient at which effective stress becomes zero and soil loses shear strength, equal to submerged unit weight divided by unit weight of water.
- Modulus of elasticity of concrete
- An estimate of concrete stiffness given by 5000 times the square root of characteristic cube strength in MPa, used in deflection calculations for reinforced concrete members.
- Development length
- The embedded length of reinforcement required to develop its design tensile stress in concrete through bond, computed from bar diameter, steel stress, and bond stress.
- Workability of concrete
- The ease with which fresh concrete can be mixed, placed, compacted, and finished without segregation; measured by slump, compaction factor, or Vee-Bee time.
- Curing of concrete
- Maintaining adequate moisture and temperature in young concrete so cement hydration continues, typically for 7 days for ordinary Portland cement and 14 days in hot weather.
- Specific gravity of soil solids
- The ratio of the mass of soil solids to the mass of an equal volume of water, typically 2.65 to 2.75 for most inorganic soils.
- Bernoulli's energy equation
- For steady incompressible flow along a streamline, pressure head plus velocity head plus elevation head remains constant, with losses added between two sections.
- Backwater curve
- The water surface profile upstream of an obstruction or downstream of a dam where depth increases gradually; computed by the direct step or standard step method.