Structural Engineering — Quiz 5

Questions in this quiz (10)

1. A short, square tied column has a minimum area of reinforcing steel of $$3.24\ \mathrm{in}^2$$ and a gross area of $$18\ \mathrm{in}^2$$. The compressive strength of the concrete is $$4000\ \mathrm{lbf/in}^2$$, and the yield strength of the concrete is $$60{,}000\ \mathrm{lbf/in}^2$$. What is most nearly the design axial compressive load capacity?

   • $$130\ \mathrm{kips}$$
   • $$140\ \mathrm{kips}$$
   • $$400\ \mathrm{kips}$$
   • $$668\ \mathrm{kips}$$

2. Determine the stability and determinacy of the beam shown.

   • Unstable
   • Stable and determinate
   • Stable and indeterminate, first degree
   • Stable and indeterminate, second degree

3. A reinforced concrete beam of normal weight concrete with an effective depth of $$16\ \mathrm{in}$$ and a width of $$12\ \mathrm{in}$$ is reinforced with grade $$60$$ bars and has a concrete compressive strength of $$3000\ \mathrm{lbf/in}^2$$. The factored shear force is $$V_u=7\ \mathrm{kips}$$, the factored moment is $$M_u=20\ \mathrm{ft\text{-}kips}$$, and the reinforcement ratio is $$\rho_w=0.015$$. What is most nearly the nominal shear reinforcement capacity required?

   • $$0\ \mathrm{kips}$$
   • $$0.9\ \mathrm{kips}$$
   • $$1.1\ \mathrm{kips}$$
   • $$1.6\ \mathrm{kips}$$

4. A steel compression member has a yield strength of $$50\ \mathrm{kips/in}^2$$ and a controlling slenderness ratio of $$31.8$$. The critical column design stress is most nearly:

   • $$40\ \mathrm{kips/in}^2$$
   • $$42\ \mathrm{kips/in}^2$$
   • $$46\ \mathrm{kips/in}^2$$
   • $$50\ \mathrm{kips/in}^2$$

5. The cross section of a beam is reinforced with $$3\ \mathrm{in}^2$$ of steel, $$f'_c=4000\ \mathrm{lbf/in}^2$$, and $$f_y=60{,}000\ \mathrm{lbf/in}^2$$. Assume that the tension steel yields at maximum moment. Most nearly, what is the area of concrete required to balance the steel force when the steel yields?

   • $$15\ \mathrm{in}^2$$
   • $$18\ \mathrm{in}^2$$
   • $$45\ \mathrm{in}^2$$
   • $$53\ \mathrm{in}^2$$

6. A reinforced concrete tied column is subjected to a design axial compression force of $$875\ \mathrm{kips}$$ and a design bending moment about its strong axis of $$740\ \mathrm{ft\text{-}kips}$$. The column cross section measures $$30\ \mathrm{in}\times 18\ \mathrm{in}$$, and the distance from the edge of the column to the center of steel in each face is $$3\ \mathrm{in}$$. The concrete's specified compressive strength is $$4000\ \mathrm{psi}$$, and the reinforcing steel is grade $$60$$. The required area of longitudinal steel is most nearly:

   • $$4.0\ \mathrm{in}^2$$
   • $$8.0\ \mathrm{in}^2$$
   • $$12\ \mathrm{in}^2$$
   • $$14\ \mathrm{in}^2$$

7. For the plane truss shown below, what is most nearly the axial force in member $$CG$$?

   • $$45.3\ \mathrm{kip}$$ compression
   • $$45.3\ \mathrm{kip}$$ tension
   • $$90.5\ \mathrm{kip}$$ compression
   • $$90.5\ \mathrm{kip}$$ tension

8. For the beam shown below, what is most nearly the largest magnitude of bending moment due to the applied loads?

   • $$0\ \mathrm{ft\text{-}kip}$$
   • $$49\ \mathrm{ft\text{-}kip}$$
   • $$72\ \mathrm{ft\text{-}kip}$$
   • $$108\ \mathrm{ft\text{-}kip}$$

9. For the plane truss shown below, what is most nearly the horizontal deflection at joint $$B$$? All members in the truss are mild carbon steel with $$E=29000\ \mathrm{ksi}$$ and cross-sectional area $$2.0\ \mathrm{in}^2$$.

   • $$0\ \mathrm{in}$$
   • $$0.97\ \mathrm{in}$$ to the right
   • $$1.46\ \mathrm{in}$$ to the right
   • $$2.61\ \mathrm{in}$$ to the right

10. For the beam shown below, what is most nearly the vertical deflection at midspan? The beam is comprised of normal-weight concrete with $$E=4000\ \mathrm{ksi}$$ and has a moment of inertia of $$1000\ \mathrm{in}^4$$.

    • $$0.01\ \mathrm{in}$$ downward
    • $$2.58\ \mathrm{in}$$ downward
    • $$4.93\ \mathrm{in}$$ downward
    • $$6.12\ \mathrm{in}$$ downward