MEngC R.S.E Part-I Civil key terms

A design philosophy that checks a structure against two conditions: the ultimate limit state, where collapse or loss of equilibrium is possible, and the serviceability limit state, where deflection, cracking or vibration makes the structure unfit for normal use.

The strength value below which no more than a stated small percentage, usually 5 percent, of test results are expected to fall. It forms the statistical basis for material grades such as M25 concrete or Fe500 steel.

A multiplier applied separately to loads and to material strengths so that design accounts for uncertainty in loading, workmanship and material variability. Load factors exceed one while material factors reduce nominal strength.

A reinforced concrete section proportioned so that concrete crushing and steel yielding occur simultaneously at ultimate load. Its steel percentage marks the boundary between under-reinforced ductile behaviour and over-reinforced brittle behaviour.

A section with steel content below the balanced value, so the tension steel yields before the concrete crushes. Failure is gradual and gives visible warning, which is why codes require ductile behaviour in flexure.

Deliberate introduction of compressive stress into concrete, usually by tensioned high-strength tendons, to counteract tensile stresses from loads. It permits longer spans and controls cracking by keeping the section largely in compression.

A prestressing method in which tendons are stressed after the concrete has hardened, then anchored against the member ends and the ducts grouted. It allows curved tendon profiles and site assembly of long spans.

Time-dependent increase in strain of concrete under sustained stress, caused by gradual movement of water within the cement paste. It increases long-term deflection and relieves some prestress force over the life of a member.

Volume reduction of concrete as it dries and as cement hydrates, occurring without applied load. Restrained shrinkage generates tensile stress and is a common cause of cracking in slabs and long walls.

The capacity of a member or material to undergo large inelastic deformation before failure while still resisting load. In seismic design, ductility allows energy dissipation and prevents sudden brittle collapse.

A vertical reinforced concrete wall designed to resist lateral forces from wind or earthquakes. Its high in-plane stiffness limits storey drift and attracts a large share of the base shear in tall buildings.

The total design lateral force at the building base produced by an equivalent static or dynamic seismic analysis. It is distributed over the height of the structure to obtain design storey forces.

A code factor that divides the elastic seismic demand to account for the structure's ability to dissipate energy through controlled inelastic behaviour. Higher values apply to detailed ductile framing systems.

The relative lateral displacement between two consecutive floors, often expressed as a ratio of the storey height. Excessive drift damages non-structural elements and indicates loss of stiffness.

The time a structure takes to complete one free oscillation in a given mode. It governs where the building sits on the response spectrum and therefore how much seismic force it attracts.

The number of redundant reactions or internal forces exceeding those needed for equilibrium. It equals the number of extra compatibility conditions required to solve the structure.

A diagram showing how a particular response, such as a reaction, shear or moment, varies as a unit load moves across the structure. It is used to place moving loads at the position giving the worst effect.

A successive-approximation technique for analysing continuous frames. Fixed-end moments are released at joints and redistributed in proportion to member stiffness until unbalanced moments become negligible.

Sudden lateral deflection of a slender member under compressive load when it reaches a critical value. The Euler load depends on effective length, flexural rigidity and end restraint, not on material strength alone.

The equivalent pin-ended length of a compression member that gives the same buckling load as the actual member with its real end conditions. It is the actual length multiplied by a factor depending on restraint.

A built-up steel beam formed from a deep web plate with flange plates welded or bolted to its edges. It is used for spans and loads beyond the range of rolled sections and requires web stiffeners against shear buckling.

The maximum pressure the soil beneath a foundation can sustain without shear failure or excessive settlement. It is computed from shear strength parameters, footing geometry and depth using a recognised theory.

An in-situ test in which a split sampler is driven into the ground by a standard drop hammer, and the blow count for the final 300 mm is recorded. The N value is used to estimate soil density and strength.

Loss of shear strength in saturated loose sand during earthquake shaking when pore water pressure rises until effective stress approaches zero. The ground then behaves like a fluid, causing settlement and foundation failure.

The ease with which freshly mixed concrete can be placed, compacted and finished without segregation. It is commonly assessed by the slump test, and the required value depends on member shape and placing method.

Maintaining adequate moisture and temperature in concrete after placing so that cement hydration can continue. Proper curing develops strength, reduces permeability and limits shrinkage cracking at early ages.

A field test in which freshly mixed concrete is placed in a standard cone, the cone is lifted, and the vertical drop of the concrete is measured. It gives a simple indication of consistency and workability.

A scheduling technique that models activities and dependencies as a network, then identifies the longest path through it. Activities on that path have zero float and any delay there delays project completion.

The amount of time an activity can be delayed without affecting the project completion date or a successor activity. Total float is measured along the network, while free float relates only to immediate successors.

A project control method comparing planned value, earned value and actual cost to measure schedule and cost performance. Cost and schedule performance indices below one indicate overrun or delay.

The process of building up a unit rate for a construction item from material quantities, labour, plant, overheads and contractor profit. It produces the rate used to price measured work in a bill of quantities.

A tender document listing measured quantities of work items against descriptions, against which bidders insert rates and amounts. It provides a common basis for comparing tenders and for interim payment valuation.

A sum reserved in an estimate or project budget for unforeseen work, price variation or risk events. It is not allocated to specific items and is released only with proper authorisation.

The surveying operation of determining the elevation of points relative to a datum using a level instrument and staff. Height differences are found from backsight and foresight readings and reduced to levels.

A permanently fixed point of known reduced level, used as the reference for levelling and setting out. Temporary bench marks are established on site for convenience during construction.

A line on a map joining points of equal elevation. Contour spacing indicates ground steepness and is used for site selection, drainage planning and earthwork estimation.

A digital, object-based representation of a building in which geometry, materials and properties are linked. It supports clash detection, quantity extraction and coordinated drawing production across disciplines.

A tabulated statement giving the mark, size, shape, cutting length and number of each reinforcing bar in a member. It is used to order steel and to compute reinforcement quantities for payment.

The legal exposure of an engineer for loss caused by negligent design, advice or certification within the scope of professional duty. It is commonly managed through insurance and clear terms of engagement.

A formal offer submitted by a contractor to execute specified work at stated rates within a stated period. Tenders are invited against drawings, specifications and a bill of quantities and evaluated before award.