WBPSC AE Civil flashcards

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

Hooke's Law

Within the proportional limit, stress is directly proportional to strain: σ = E·ε, where E is Young's modulus (≈200 GPa for steel).

Euler Buckling Load

Critical axial load for a slender column: P_cr = π²EI/(L_e)², where L_e is the effective length depending on end conditions.

Static Indeterminacy

Number of redundant reactions or internal forces beyond those needed for equilibrium; for a plane frame D_s = 3m + r – 3j.

Müller-Breslau Principle

The influence line for a response function equals the deflected shape produced by releasing the corresponding restraint and imposing a unit displacement.

Limit State of Collapse

IS 456 design method ensuring the structure does not collapse under factored loads; uses partial safety factors 1.5 (dead + live) and 1.2 (dead + wind).

Development Length

Embedded length required to develop the design stress in a reinforcing bar: L_d = φ·σ_s/(4·τ_bd); τ_bd = 1.6 MPa for deformed bars in M25 concrete.

Reynolds Number

Dimensionless ratio Re = ρVD/μ = VD/ν; laminar pipe flow Re < 2000, transitional 2000–4000, turbulent Re > 4000.

Manning's Equation

Open-channel velocity formula V = (1/n)·R^(2/3)·S^(1/2), where n is roughness, R hydraulic radius, S bed slope.

Rational Method

Peak discharge estimate Q_p = C·i·A/3.6 (Q in m³/s, i in mm/h, A in km²), with C a runoff coefficient depending on land use.

Unit Hydrograph

Direct runoff hydrograph resulting from 1 cm of effective rainfall uniformly distributed over a catchment in a specified duration.

BOD₅

Biochemical oxygen demand exerted over five days at 20 °C; related to ultimate BOD by BOD₅ = BOD_u(1 – e^(–5k)), k ≈ 0.1–0.3/day.

Surface Overflow Rate

Settling tank design parameter SOR = Q/A, representing the settling velocity of the slowest particle completely removed; typical 15–30 m³/m²·d.

Terzaghi Bearing Capacity

Ultimate bearing capacity of a strip footing: q_u = c·N_c + q·N_q + 0.5·γ·B·N_γ, with N factors depending on the friction angle φ.

Coefficient of Consolidation

c_v = T_v·H_dr²/t; describes the rate of pore pressure dissipation in a clay layer, determined from oedometer test data.

Stopping Sight Distance

Minimum distance for a vehicle to stop safely: SSD = 0.278·V·t + V²/(254(f ± g)), with V in km/h, t reaction time (2.5 s), f friction coefficient.

Superelevation

Transverse slope on a horizontal curve to counter centrifugal force: e + f = V²/(127R); maximum e = 7% in plain terrain.

Bowditch's Rule

Traverse adjustment distributing closing error in proportion to line lengths: correction to latitude = –ΣL·(l/Σl), and similarly for departures.

Tacheometric Distance Formula

Horizontal distance D = K·s·cos²θ + C·cosθ, where K = 100, C = 0 for an anallatic lens, s staff intercept, θ vertical angle.

Le Chatelier Soundness Test

Cement expansion test; the distance between indicator needles after boiling must not exceed 10 mm for sound cement (IS 4031).

Abrams' Law

Concrete strength is inversely related to water-cement ratio: strength = A/B^(w/c), where A and B are empirical constants.

PERT Expected Time

t_e = (t_o + 4t_m + t_p)/6, where t_o, t_m and t_p are optimistic, most likely and pessimistic activity durations.

Earned Value CPI

Cost Performance Index = EV/AC; CPI > 1 indicates under budget, CPI < 1 over budget; used to forecast EAC = BAC/CPI.

Duty and Delta

Duty D (ha/cumec) and delta Δ (m) relate by Δ = 8.64·B/D, where B is the base period in days for the crop.

Lacey's Regime Equations

Stable canal design: V = (Q·f²/140)^(1/6) and R = 0.47(Q/f)^(1/3), with silt factor f = 1.76√d_mm.

Article 32

Constitutional right to move the Supreme Court for enforcement of Fundamental Rights through writs of habeas corpus, mandamus, prohibition, quo warranto and certiorari.

Damodar Valley Corporation

India's first multipurpose river valley project, established in 1948, modelled on the Tennessee Valley Authority, serving West Bengal and Jharkhand.

Whistle-Blowing

Disclosure of wrongdoing by an engineer when public safety, health or welfare is at risk; ethically justified after internal channels fail.

Conflict of Interest

Situation where personal or financial interests could bias professional judgement; must be disclosed and avoided in engineering decisions.

Principal Stresses

Normal stresses on planes of zero shear: σ₁,₂ = (σ_x + σ_y)/2 ± √[((σ_x – σ_y)/2)² + τ_xy²]; maximum shear = (σ₁ – σ₂)/2.

Three-Moment Equation

Continuity condition for continuous beams: M_A·L₁ + 2M_B(L₁ + L₂) + M_C·L₂ = –6(A₁x₁/L₁ + A₂x₂/L₂) for constant EI.

Shear Lag Effect

Non-uniform stress distribution across wide steel plates or box sections; effective width concept accounts for it in design of tension members.

Hydraulic Jump

Rapid transition from supercritical to subcritical flow; conjugate depths satisfy y₂/y₁ = ½(√(1 + 8F₁²) – 1), with energy loss.