TNPSC AE Civil key terms

A design approach in which a structure is checked against defined failure conditions such as collapse or excessive deflection, using partial safety factors on loads and material strengths rather than a single working stress.

The strength value of a material below which not more than five percent of test results are expected to fall, taken as the basis for design in limit state codes.

A multiplier applied separately to loads or to material strengths to account for uncertainty, variability and the consequences of failure in limit state design.

For a compression member, the ratio of its effective length to its least radius of gyration; higher values mean the member buckles at a lower stress.

The theoretical axial load at which a long, slender, perfectly straight elastic column becomes unstable and deflects laterally, equal to pi squared EI divided by effective length squared.

The equivalent pin-ended length of a compression member that gives the same buckling load as the actual member with its real end restraints.

A geometric property of a cross-section equal to the square root of the second moment of area divided by area; it measures how far material sits from the axis.

The second moment of area of a section about a chosen axis, expressing its resistance to bending; larger values produce smaller curvature for the same applied moment.

The ratio of a section's moment of inertia to the distance from the neutral axis to its extreme fibre; it converts bending moment into maximum bending stress.

The line within a bending cross-section where longitudinal stress is zero and which separates the compression zone from the tension zone.

A plot showing how the internal transverse shear force varies along a beam; its slope at any point equals the applied distributed load there.

A plot of internal bending moment along a beam, whose slope equals the shear force; its maximum value locates the most heavily stressed section.

A beam fixed at one end and simply supported at the other, making it statically indeterminate to the first degree and requiring compatibility of deflection for analysis.

Describing a structure whose support reactions and internal forces cannot be found from equilibrium equations alone, so deformation compatibility conditions must also be used.

The bending moment that develops at a fully restrained beam end when the span carries load with no rotation permitted at that support.

A successive-approximation technique for indeterminate frames in which unbalanced joint moments are released and redistributed according to member stiffness until residual moments become negligible.

The ease with which fresh concrete can be mixed, transported, placed and compacted without segregation; commonly assessed by slump, compaction factor or vee-bee tests.

A simple field test in which a moulded concrete cone is lifted and the vertical drop of the concrete is measured to indicate consistency and workability.

The ratio of the mass of concrete partially compacted by free fall to the mass when fully compacted, used to quantify workability of drier mixes.

The separation of coarse aggregate from mortar or of water from solids in a concrete mix, usually caused by excess water, over-vibration or long transport.

The upward migration of mixing water to the surface of freshly placed concrete as solids settle, which can weaken the top layer and reduce bond.

The mass of water divided by the mass of cement in a mix; it governs strength and durability, with lower values generally giving stronger, less permeable concrete.

Keeping concrete moist and at a favourable temperature after placing so that cement hydration continues and the designed strength and durability develop.

The increase in apparent volume of moist sand caused by films of water pushing grains apart, which must be corrected when batching by volume.

A test in which an aggregate sample is shaken through a stack of standard sieves to determine the particle size distribution and grading of the material.

The ratio of the mass of a material to the mass of an equal volume of water, used for soils and aggregates in mix design and density calculations.

The volume of voids in a soil mass divided by the volume of solids; it indicates how loose or dense a soil is and influences compressibility and permeability.

The property of a porous material that describes how readily water flows through it under a hydraulic gradient, expressed by Darcy's coefficient of permeability.

The gradual reduction in volume of a saturated soil under sustained load as water is squeezed out of its pores, causing time-dependent settlement.

The water content at which a fine-grained soil passes from a plastic to a liquid state, determined by the Casagrande apparatus or cone penetrometer.

The difference between the liquid limit and the plastic limit of a soil, indicating the range of water content over which it behaves plastically.

The ratio of liquid limit minus natural water content to plasticity index, expressing how stiff a cohesive soil is relative to its plastic range.

The maximum pressure a soil or rock can safely carry at the base of a foundation without shear failure or excessive settlement.

The downward movement of a foundation or structure caused by compression of the supporting soil, either immediately, by consolidation, or by secondary creep.

A temporary watertight enclosure built in a river or wet ground so that construction can proceed in the dry inside it.

A deep foundation element sunk through soil or water to a bearing stratum, often using compressed air or open excavation, and later filled with concrete.

The controlled removal of groundwater from an excavation by pumping or wellpoints to keep the working area dry and stable.

A compulsory Tamil language paper in Tamil Nadu recruitment examinations that both qualifies candidates and adds marks to the total, testing grammar, comprehension and usage.

A classical Tamil work of 1330 couplets by Thiruvalluvar, arranged in three sections on virtue, wealth and love, frequently quoted in Tamil language papers.

The earliest body of classical Tamil poetry, composed roughly between 300 BCE and 300 CE, divided into akam themes of love and puram themes of war and public life.