Question

Two ISMC 350 channel section are placed back to back to form a built-up section for the column as shown in the figure below.


The minimum spacing 's' so that it can carry maximum compressive load will be ________ mm.

The properties of ISMC 350 are as follows:

$\text{Cross - sectional area (A)}=5366m{m}^2$
$C_{yy}=24.4mm$
$I_{zz}=10008c{m}^4$
$I_{yy}=430.6c{m}^4$

• A. 172.53
• B. 140.14
• C. 262.70
• D. 218.4

Answer 1

The correct option is D 218.4

Maximum compressive load will be carried by build -up section when
$I_{zz}^{\prime }={I_{yy}}^{\prime }$
$2I_{zz}=2I_{yy}+2A{(\frac{s}{2}+C_{yy})}^2$
$2\times 10008\times {10}^4=2\times 430.6\times {10}^4+2\times 5366{(\frac{s}{2}+24.4)}^2$
$s=218.395mm\simeq 218.4mm$