$3\mathrm{.}9$ PROBLEMS

Repeat the example in Section $3\mathrm{.}4\mathrm{.}6$ with the equivalent stress block, assuming an

intensity of $0\mathrm{.}85f_c^{\text{'}}$ where $f_c^{\text{'}}=65$MPa. Draw the $M^{\text{'}}$ versus $p_t$ curves for the two values

of equivalent stress block intensities on the same diagram $($similar to Figure $3\mathrm{.}4(4))$ and

discuss the significance of using ${}_2$ in place of $0\mathrm{.}85$ in the new Standard.

A singly reinforced rectangular section having a cross$-$section $b=300mm$ and

$d=600mm$ is reinforced by $10$ N $32$ bars. Assuming $f_c^{\text{'}}=32$MPa, compute the reliable

moment capacity of the section $($i$.$e$.M_u).$

Details of a one$-$way slab are illustrated in Figure $3\mathrm{.}9(1).$ Based on the load combination

formula, ultimate load $=1\mathrm{.}2g+1\mathrm{.}5q,$ compute the uniformly distributed live load $(q)$

that may be carried by the slab. Take $f_c^{\text{'}}=25$MPa and ${}_w=24k\frac{N}{m^3}.($Hint: take a

typical strip $1000$ mm wide and analyse it as a simply supported beam.$)$