Structural Engineering — Quiz 4

Questions in this quiz (10)

1. When analyzing a statically indeterminate truss using the flexibility method, the redundant member force is determined by:

   • Summing moments about all joints
   • Applying the compatibility condition that the displacement in the direction of the redundant equals zero (or a specified value)
   • Using the stiffness of the redundant member only
   • Ignoring the effects of the redundant member on other members

2. A composite beam (steel beam with concrete slab) has a transformed moment of inertia $$I_{tr}=3500\ \mathrm{in^4}$$. Under a bending moment of $$250\ \mathrm{kip\text{-}ft}$$, the distance from the neutral axis to the bottom of the steel beam is $$12$$ in. Determine the bending stress at the bottom of the steel.

   • 0.86 ksi
   • 5.14 ksi
   • 10.29 ksi
   • 20.57 ksi

3. A T-section has a flange $$12$$ in $$\times$$ $$3$$ in and a web $$3$$ in $$\times$$ $$12$$ in, with the web below the flange. The neutral axis is located $$9.75$$ in from the bottom. Calculate the first moment of area $$Q$$ about the neutral axis for the area above the neutral axis.

   • $$71.3 in^3$$
   • $$135.0 in^3$$
   • $$142.6 in^3$$
   • $$285.0 in^3$$

4. A $$10$$-ft steel cantilever carries an applied dead load of $$10$$ kips/ft and a live load of $$5$$ kips/ft over its span. The maximum moment at the ultimate load is nearly:

   • 150
   • 750
   • 1,000
   • 1,500

5. A $$16$$-ft steel cantilever is $$W16\times57$$ and carries a uniformly distributed dead load of $$1.0$$ kip/ft and a live load of $$0.8$$ kip/ft over its span. The maximum deflection at the ultimate load of the cantilever is nearly:

   • 0.001
   • 0.01
   • 1.0
   • 1.6

6. A W24×55 (Fy = 50 ksi) is used as a simply supported beam (span = 12 ft) to support a uniformly distributed load. Taking Cb = 1.0, determine the maximum design flexural capacity using LRFD when only the ends are laterally supported.

7. A fixed-fixed beam carries a 9 kN load located 5 m from support A and 10 m from support B. Determine the maximum vertical reaction at support A.

   • 503 ft-kip
   • 344 ft-kip
   • 299 ft-kip
   • 150 ft-kip

8. Determine the fixed-end moment for a fixed-fixed beam subjected to a uniform load of 2 kips/ft over a 15 ft span.

   • 3 kN
   • 6 kN
   • 7 kN
   • 8 kN

9. A steel column has slenderness ratio KL/r = 80 and modulus of elasticity E = 200,000 MPa. Determine Euler critical buckling stress.

   • 25.0
   • 37.5
   • 45.0
   • 60.0

10. For reinforced concrete with fc = 4000 psi, fy = 60000 psi, and β1 = 0.85, determine the balanced reinforcement ratio.

    • 98.2 MPa
    • 154.2 MPa
    • 246.7 MPa
    • 308.4 MPa