Example $4\mathrm{.}5$:

Ideal spiral reinforcement required for spiral columns shown in Figure $4\mathrm{.}10($a$)$ and $($b$)$ will be calculated. Concrete is C$25,$ longitudinal reinforcement and spirals are B$420$C$.$

$($a$)$

$($b$)$

Figure $4\mathrm{.}10$: