Iran Nezam Civil Design Exam flashcards

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

Static determinacy condition

A plane frame is statically determinate when 3m + r = 3j + c, where m is members, r reactions, j joints, and c internal releases.

Virtual work deflection

External work by a unit load equals internal work: 1·Δ = Σ∫(M·m/EI)ds + Σ∫(N·n/EA)ds + Σ∫(V·v/GA)ds, summing bending, axial, and shear contributions.

Euler buckling load

Critical buckling load P_cr = π²EI/(KL)², where K depends on end conditions: 1.0 pinned-pinned, 0.5 fixed-fixed, 0.7 fixed-pinned, 2.0 cantilever.

Slope-deflection equation

M_AB = 2EI/L(2θ_A + θ_B − 3Δ/L) + FEM_AB; used to solve indeterminate frames by joint equilibrium with consistent sign conventions.

Balanced steel ratio

ρ_b = 0.85·β₁·(f'c/f_y)·(0.003/(0.003 + ε_y)); for Grade 60 steel ε_y ≈ 0.00207, giving ρ_b ≈ 0.85·β₁·(f'c/f_y)·0.59.

Nominal flexural strength

M_n = A_s·f_y·(d − a/2) with a = A_s·f_y/(0.85·f'c·b); a tension-controlled section requires net tensile strain ε_t ≥ 0.005.

One-way concrete shear capacity

V_c = 0.17·λ·√f'c·b_w·d in SI units (MPa, mm); design strength φV_n must equal or exceed the factored shear demand V_u.

Cracked effective moment of inertia

I_e = (M_cr/M_a)³·I_g + [1 − (M_cr/M_a)³]·I_cr, where M_cr = f_r·I_g/y_t; used for deflection calculations under service loads.

Shear lag factor U

A reduction factor applied to net area for tension members: A_e = U·A_n, accounting for nonuniform stress distribution across the connection.

Lateral-torsional buckling limit

Full plastic moment F_y·Z_x is available only when L_b ≤ L_p = 1.76·r_y·√(E/F_y); beyond L_p, strength reduces by LTB.

Beam-column interaction equation

If P_u/(φP_n) ≥ 0.2, use P_u/(φP_n) + (8/9)·M_u/(φM_n) ≤ 1.0; otherwise use P_u/(2φP_n) + M_u/(φM_n) ≤ 1.0.

Fillet weld throat

Effective throat equals 0.707 times the weld leg size w; nominal strength R_n = 0.6·F_EXX·(0.707·w)·L for a fillet weld of length L.

Terzaghi bearing capacity

For a strip footing: q_ult = c·N_c + q·N_q + 0.5·γ·B·N_γ, with N factors depending on the soil friction angle φ.

Effective stress principle

Effective stress σ' = σ − u, where u is pore water pressure; soil strength and settlement depend on effective, not total, stress.

Consolidation settlement

S_c = C_c·H/(1 + e_0)·log₁₀[(σ'_0 + Δσ)/σ'_0] for normally consolidated clay, where C_c is compression index and e_0 initial void ratio.

Rankine active coefficient

K_a = (1 − sin φ)/(1 + sin φ); total active thrust on a wall of height H is 0.5·γ·H²·K_a, acting at H/3 above the base.

Pile ultimate capacity

Q_ult = q_p·A_p + Σ f_s·A_s·ΔL, combining end-bearing q_p·A_p and skin friction f_s along the shaft; in clay f_s = α·c_u.

Seismic base shear

V = C_s·W, where C_s = S_DS/(R/I_e), with lower bound 0.044·S_DS·I_e and upper bound S_D1/(T·(R/I_e)).

Approximate fundamental period

T_a = C_t·h_n^x; for moment-resisting frames C_t = 0.0466 and x = 0.9 in SI units, where h_n is building height in meters.

Vertical seismic force distribution

F_i = (w_i·h_i^k / Σw_j·h_j^k)·V, with k = 1 for T ≤ 0.5 s and k = 2 for T ≥ 2.5 s, interpolated between.

Story drift limit

Design story drift Δ is limited to 0.02·h_sx for most structures in Risk Category I/II; drift is computed from amplified elastic displacements.

Abrams' law

Compressive strength relates to water-cement ratio as f_c = A/B^(w/c); lower w/c gives higher strength but reduced workability.

Entrained air content

Typically 5–8% by volume for 20–25 mm aggregate in freeze-thaw exposure; air voids relieve pressure from ice crystallization in capillary pores.

Concrete modulus of elasticity

For normal-weight concrete, E_c = 4700·√f'c MPa (λ = 1.0); unit weight is approximately 24 kN/m³ for normal-weight mixes.

Total float formula

TF = LS − ES = LF − EF; free float FF = ES_successor − EF_activity; critical activities have zero total float.

Earned value indices

CPI = EV/AC and SPI = EV/PV; CPI below 1 indicates cost overrun, SPI below 1 indicates schedule slippage.

PERT expected duration

t_e = (a + 4m + b)/6, with variance σ² = ((b − a)/6)²; project variance is the sum of critical-path activity variances.

Crash cost slope

Cost slope = (crash cost − normal cost)/(normal duration − crash duration); crash the critical activity with the lowest slope first.

Occupant load factor

For offices, 9.3 m² gross per person; required egress width for level components is 5 mm per person per exit.

Importance factor values

I_e = 1.0 for Risk Category I/II, 1.25 for Category III, and 1.5 for Category IV; it amplifies seismic design forces.

Differential leveling relation

ΔElevation = BS − FS; the height of instrument HI = benchmark elevation + backsight, and new point elevation = HI − foresight.

Horizontal curve tangent

T = R·tan(Δ/2), L = R·Δ_rad, E = R·(sec(Δ/2) − 1), M = R·(1 − cos(Δ/2)); Δ is the central deflection angle.

Manning's equation

Q = (1/n)·A·R^(2/3)·S^(1/2), where R = A/P is hydraulic radius and S is channel slope; n is Manning's roughness coefficient.

Rational method runoff

Q = C·i·A, where C is the runoff coefficient (0.9 pavement, 0.2 lawn), i is rainfall intensity, and A is drainage area.