Civil Engineering PE Steel Structure Design Methods 3

Question 1

A steel column with KL/r = 80 and Fy = 50 ksi falls into which AISC buckling category?

Accepted Answer

Inelastic buckling (KL/r < 4.71√(E/Fy) ≈ 113)

Answer

Elastic buckling (KL/r > 113)

Answer

No buckling concern (KL/r < 25)

Answer

Post-buckling reserve applies

Question 2

Which effective length factor K applies to a column with both ends pinned (no rotational fixity)?

Accepted Answer

K = 1.0

Answer

K = 0.5

Answer

K = 0.7

Answer

K = 2.0

Question 3

What is the purpose of the Cb factor in AISC beam design?

Accepted Answer

It accounts for non-uniform moment along the unbraced length, allowing higher capacity

Answer

It reduces nominal strength for compact sections

Answer

It adjusts for weak-axis bending

Answer

It accounts for residual stresses in rolled shapes

Question 4

In AISC Chapter F, which condition defines a compact section regarding the compression flange?

Accepted Answer

λ ≤ λp where λ = bf/2tf ≤ 0.38√(E/Fy)

Answer

λ ≤ λr where λ = bf/2tf ≤ 1.0√(E/Fy)

Answer

λ ≤ λp where λ = h/tw ≤ 2.24√(E/Fy)

Answer

No flange slenderness limit applies to rolled W-shapes

Question 5

For a steel beam experiencing lateral-torsional buckling in the elastic range, nominal moment Mn is proportional to:

Accepted Answer

1/Lb² (inversely proportional to unbraced length squared)

Answer

Lb (proportional to unbraced length)

Answer

Lb⁰·⁵ (square root of unbraced length)

Answer

Constant (independent of unbraced length)

Question 6

Which AISC design method uses Ω (omega) as the safety factor applied to nominal strength?

Accepted Answer

ASD (Allowable Strength Design)

Answer

LRFD (Load and Resistance Factor Design)

Answer

Both methods equally

Answer

Neither; both use φ factors

Question 7

A W14×82 steel column (A = 24.0 in²) with Fy = 50 ksi and φcFcr = 38.2 ksi has a design axial strength of:

Accepted Answer

917 kips

Answer

1,200 kips

Answer

760 kips

Answer

1,000 kips