1. A Compression member subjected to compresive force along it centroidal axis is called a column.
   1. different term used in a column depending upon it position in structure the compression member in roof truss of bracinf are term as strut They are normally provided as small span & may be vertical or inclined
   2. effective length of compression member if length measure between two point of contraflexure of buckled load
   3. Slenderness ratio $\lambda$ is define as ratio of effective length (leff)or compression member should be as small as possible so that material can stressed to it maximum limit $\lambda=\frac{kl}{r}$ fcd
   4. effective cross section area of column is grass cross section area because bolt replaced the material remove from the hales
   5. design strength of compression member pd=Ae$\times$fcd

Note

1. Assume design stress gompa from single & double
2. from I section $\lambda$=100 that is design stress =118mpa about y axis of class B
3. design stress 150 mpa for compound section

Design strength of compression member

pd=Ae$\times$fcd

fcd =$\frac{fy/\gamma ma}{\phi [\phi^{2}-\lambda^{2}]^{0.5}}$=$\chi \frac{fy}{\lambda mo}\leq \frac{fy}{\gamma mo}$

$\phi=0.5[1-\alpha(\lambda-0.2)+\lambda^{2}]$

$\lambda=\sqrt{\frac{fy\times(\frac{Kl}{x})^{2}}{\Pi^{2}\epsilon}}$

Angle

$\lambda e=\sqrt{k1+k2\lambda v^{2}+k3\lambda\phi^{2}}$

$\lambda vv=\frac{l/rvv}{\epsilon\sqrt{\frac{\Pi^{2}E}{250}}}$

$\lambda=\frac{(b1+b2)/2t}{\sqrt{\frac{Pi E}{250}}}$