MEngC R.S.E Part-I Civil flashcards

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

Degree of static indeterminacy

For a planar frame, DSI = 3m + r - 3j, where m is number of members, r is number of reaction components, and j is number of joints.

Castigliano's second theorem

The deflection at a point in a structure equals the partial derivative of total strain energy with respect to a force applied at that point in the direction of deflection.

Euler buckling load

The critical buckling load for a pin-ended column is P_cr = π²EI/L², where E is modulus, I is moment of inertia, and L is effective length.

Moment distribution carry-over factor

The carry-over factor is 0.5 when the far end is fixed and 0 when the far end is pinned; it distributes unbalanced moment to adjacent members in proportion to stiffness.

Limit state of collapse in flexure

Per IS 456, design moment M_u = 0.36 f_ck b x_u (d - 0.42 x_u), with x_u limited to 0.53d for Fe415 steel to ensure ductile failure.

Development length

Development length L_d = φ σ_s / (4 τ_bd), where φ is bar diameter, σ_s is stress in steel, and τ_bd is design bond stress (1.6 MPa for plain bars in tension).

Minimum eccentricity in columns

For a column, minimum eccentricity e_min = L/500 + D/30, subject to a minimum of 20 mm, where L is unsupported length and D is lateral dimension.

Flat slab direct design method

Total design moment M_o = w L_n²/8; negative moment at column = 0.65 M_o and positive moment = 0.35 M_o for an interior panel.

Plastic section modulus

The plastic section modulus Z_p is the sum of the first moments of area of the section about the equal area axis; design bending strength M_d = β_b Z_p f_y / γ_m0.

Fillet weld design strength

Design strength f_wd = f_u / (√3 γ_mw), with γ_mw = 1.25 for shop welds and 1.50 for site welds; throat thickness = 0.7 × weld size.

Shear capacity of steel section

Shear capacity V_d = A_v f_yw / (√3 γ_m0), where A_v is shear area, f_yw is yield strength of web, and γ_m0 = 1.10.

Limiting width-to-thickness ratio

For plastic design, outstanding flange b/t_f ≤ 9.4ε and web d/t_w ≤ 84ε for a plastic section, where ε = √(250/f_y).

Terzaghi bearing capacity

For a strip footing, ultimate bearing capacity q_u = c N_c + q N_q + 0.5 γ B N_γ, where N_c, N_q, N_γ depend on the angle of internal friction φ.

Consolidation settlement

S_c = (C_c H / (1 + e_0)) log10((σ'_0 + Δσ)/σ'_0), where C_c is compression index, e_0 is initial void ratio, H is layer thickness, and Δσ is stress increase.

Liquefaction factor of safety

F_L = CRR / CSR, where CSR = 0.65 (σ_v/σ'_v) (a_max/g) r_d; F_L < 1 indicates liquefaction susceptibility.

Pile ultimate capacity

Q_u = Q_p + Q_s = q_p A_p + Σ f_s A_s, where q_p is unit end bearing, A_p is pile tip area, f_s is unit skin friction, and A_s is shaft area.

Natural frequency of SDOF system

ω_n = √(k/m) and period T = 2π√(m/k), where k is stiffness and m is mass of the single-degree-of-freedom system.

IS 1893 zone factor

Seismic zone factor Z: Zone II = 0.10, Zone III = 0.16, Zone IV = 0.24, Zone V = 0.36; used in base shear calculation V_b = A_h W.

Response reduction factor

R = 5.0 for special moment resisting RC frames, 3.0 for ordinary RC frames, and 4.0 for steel special moment frames, reducing design seismic force.

Critical damping

Critical damping c_c = 2√(km) = 2mω_n; typical damping ratios: steel 2%, reinforced concrete 5%, masonry 10%.

Target mean strength of concrete

Per IS 10262, f'_ck = f_ck + 1.65 s, where f_ck is characteristic strength and s is standard deviation (e.g., 4 MPa for M20).

Water-cement ratio limits

IS 456 limits: 0.50 for mild exposure, 0.45 for moderate, 0.40 for severe, 0.35 for very severe, and 0.30 for extreme exposure.

Ultrasonic pulse velocity

UPV > 4.5 km/s indicates good quality concrete, 3.5–4.5 km/s medium, and < 3.5 km/s doubtful; used for non-destructive quality assessment.

Curing duration

Minimum curing: 7 days for ordinary Portland cement concrete, 10 days with mineral admixtures, and 14 days for concrete with pozzolana (IS 456).

Total float

Total float = LS - ES = LF - EF; critical activities have zero total float and determine the project duration in CPM.

PERT expected time

Expected time t_e = (t_o + 4t_m + t_p)/6; variance σ² = ((t_p - t_o)/6)²; used for probabilistic project scheduling.

Cost Performance Index

CPI = EV/AC, where EV is earned value and AC is actual cost; CPI < 1 indicates the project is over budget.

Centre line method

Estimation method where total length is the sum of centre line lengths of all walls; quantity = total length × width × height, suitable for same-thickness walls.

Prismoidal rule

Volume V = (L/6)(A_1 + 4A_m + A_2), where A_m is mid-section area; more accurate than trapezoidal rule for varying cross-sections.

IS 456:2000

Indian Standard code of practice for plain and reinforced concrete design, covering materials, workmanship, design methods, and detailing requirements.

Height of instrument

HI = RL of benchmark + backsight; RL of new point = HI - foresight; arithmetic check: ΣBS - ΣFS = last RL - first RL.

Total station coordinates

Coordinates computed as X = X_0 + D sinθ and Y = Y_0 + D cosθ, where D is horizontal distance and θ is azimuth angle.