What does LRFD stand for in steel design?

Load and Resistance Factor Design

True or False: In LRFD, resistance factors (φ) are always less than 1.0.

True. Resistance factors are always less than 1.0 to provide safety margin.

The fundamental LRFD inequality is φRₙ ≥ _____.

ΣγᵢQᵢ (sum of factored loads)

Which limit state involves complete failure or fracture of steel members?
A) Yielding
B) Buckling
C) Rupture
D) Serviceability

C) Rupture

What is the typical relationship between LRFD and ASD factors?

Φ × Ω ≈ 1.5

For tension member gross section yielding, what is the LRFD resistance factor φₜ?

0.90

True or False: Net area accounts for material removed by bolt holes.

True. Net area subtracts hole area from gross area.

The effective net area Aₑ equals Aₙ times _____.

U (shear lag factor)

What does the shear lag factor U account for in tension members?
A) Stress concentration
B) Material properties
C) Non-uniform stress distribution
D) Temperature effects

C) Non-uniform stress distribution

Why is block shear rupture checked in bolted connections?

It combines tension rupture and shear failure on perpendicular planes.

The slenderness ratio for compression members is _____.

KL/r

True or False: A column with both ends pinned has an effective length factor K = 0.5.

False. Both ends pinned gives K = 1.0.

What happens when KL/r exceeds 4.71√(E/Fᵧ)?
A) Inelastic buckling
B) Elastic buckling
C) Local buckling
D) No buckling

B) Elastic buckling

Compact cross-sections can reach _____ capacity before buckling.

Full plastic

How are steel cross-sections classified based on width-thickness ratios?

Compact, non-compact, or slender based on λₚ and λᵣ limits.

The plastic moment capacity Mₚ equals _____.

FᵧZ (yield stress times plastic section modulus)

True or False: Lateral-torsional buckling only affects compression members.

False. It affects beams when compression flanges buckle laterally.

For beams with Lb ≤ Lₚ, what is the moment capacity?
A) 0.7FᵧSₓ
B) Mₚ
C) FcrSₓ
D) CbMₚ

B) Mₚ (full plastic moment)

What does Cb represent in lateral-torsional buckling equations?

Lateral-torsional buckling modification factor for non-uniform moments.

When does a beam experience elastic lateral-torsional buckling?

When unbraced length Lb exceeds Lr (limiting unbraced length).

The nominal shear strength formula Vₙ = 0.6FᵧAw applies when _____.

Cv = 1.0 (for stocky webs)

True or False: Typical deflection limit for floor beams under live load is L/360.

True. L/360 is the common serviceability limit.

For beam-columns with Pr/Pc ≥ 0.2, the interaction equation uses coefficient _____.

8/9 (for moment terms)

What causes P-δ effects in beam-columns?
A) Story drift
B) Member deflection
C) Material yielding
D) Connection slip

B) Member deflection

Second-order moment amplification uses factors B₁ and _____.

B₂

For A325 bolts with threads included, the nominal shear stress Fₙᵥ is _____ ksi.

54

True or False: Bolt bearing strength depends on edge distance and material thickness.

True. Both Lc (edge distance) and t (thickness) affect bearing.

The maximum bearing stress formula includes the limit 2.4db times _____.
A) Fu
B) Fy
C) t
D) Lc

C) t (material thickness)

In slip-critical connections, what does the slip coefficient μ represent?

Friction between faying surfaces (0.30 Class A, 0.50 Class B).

When bolts experience combined shear and tension, which interaction applies?

F'ₙᵥ = Fₙᵥ(1 - fᵣₜ/1.3Fₙₜ) or elliptical interaction equation.

For E70 electrodes, the weld strength coefficient 0.60FEXX equals _____ ksi.

42

True or False: Effective throat area per unit length for fillet welds is 0.707w.

True. The 0.707 factor accounts for weld throat geometry.

Minimum fillet weld size for 1/2 inch thick material is _____.
A) 1/8 in
B) 3/16 in
C) 1/4 in
D) 5/16 in

B) 3/16 in

Why must fillet weld effective length be at least four times weld size?

To ensure adequate load transfer and prevent premature weld failure.

In eccentric bolt groups, torsional shear on a bolt equals _____.

Tρ/Ip (moment times distance divided by polar moment)

True or False: The instantaneous center method is more accurate than elastic method for eccentric loading.

True. It better represents actual bolt group behavior under eccentric loads.