HW $9-$ CONCRETE

MULTIPLE CHOICE $(6\mathrm{.}25$PT EACH$)$

Which of the following materials are NOT included in the main mixture that makes up Concrete?

a$.$ Water

b$.$ Cement

c$.$ Aggregates

d$.$ Steel fibers

e$.$ All of the above

How long does it take for Concrete to reach its design strength?

a$.3$ days

b$.7$ days

c$.14$ days

d$.28$ days

Concrete is naturally very strong in which type of stress:

a$.$ Compression

b$.$ Tension

c$.$ Shear

d$.$ Torsion

e$.$ All of the above

Concrete is naturally very weak in which type of stress:

a$.$ Compression

b$.$ Tension

c$.$ Shear

d$.$ Torsion

e$.$ All of the above

Steel reinforcing bars $($rebar$)$ are typically placed where in a reinforced concrete beam to resist tension?

a$.$ Along the top

b$.$ Along the middle

c$.$ Along the bottom

d$.$ Even distributed all around

e$.$ All of the above

Which type of reinforcement in a beam is used to resist Shear?

a$.$ Top bars

b$.$ Bottom bars

c$.$ Stirrups

d$.$ Reinforced concrete beams don't typically have shear reinforcement

In which direction does cracking in a concrete beam indicate a shear failure?

a$.$ Vertical

b$.$ Diagonal

c$.$ Horizontal

d$.$ All of the above

What is the correct LRFD Load Combination for Dead Load $+$ Live Load?

a$.DL+LL$

b$.1\mathrm{.}2DL+LL$

c$.1\mathrm{.}4DL+1\mathrm{.}2LL$

d$.1\mathrm{.}2DL+1\mathrm{.}6LL$