ANSWER THE FOLLOING. BE AS CONCISE AS POSSIBLE. USE DIAGRAMS WHEN NEEDED TO EXPLAIN YOUR IDEAS.

$(20$ PTS$.)$

a$.$ Name four $(4)$ types of loads to which a structure may be subject and briefly explain them. $(41pts.)$

b$.$ Draw the concrete stress$-$strain curve $($assume a maximum stress of $4,000$ psi in compression and a unit weight of

$150$ pcf$).(5$ pts$.)$

c$.$ Explain what a compression$-$controlled section, a balanced section, a transition section, and a tension$-$controlled

section are. $(41$ pts$.)$ HINT $-$ Use a drawing.

d$.$ Mention and briefly explain the two $(2)$ main limit states used in reinforced concrete structural analyses and their

associated design philosophies. pts$.)$

e$.$ List three $(3)$ of the assumptions made in formulating the theory of bending resistance of concrete sections.

pts$.$