written 5.7 years ago by |
ISMB 350
Area A=$6671mm^{2}$ bd140 tf=142 tw=81
rxx=r28=142.9
ryy=28.4
length of column =3000mm
leff=$k\times L=1\times 3000=3000m$
fy=250N/mm$^{2}$
fa=410N/mm$^{2}$
E=2$\times10^{5}N/mm^{2}$
Design strength of comp member
Pd=$Ae\times fcd$
buckling class(Is pg 44)Is pg 35 table 7
$\frac{h}{bf}=\frac{350}{140}=2.5$
${h}{bf}=2.5\geq1.2$
tf=1.42$\lt 40$
huckling about zz axis class a
buckling about yy axis class b
$\alpha=0.21$ class a
$\alpha=0.34$ class b
buckling about z axis a
$\alpha$=0.21
$\lambda_{z}=\sqrt{\frac{fy\times(\frac{kl}{\gamma zz)^{2}})}{\Pi^{2} E}}$
=$\sqrt{\frac{250\times(2000/28.4)^{2}}{\Pi^{2}\times2\times 10^{5}}}$
$\lambda y=1.189$
$\phi =0.5[1+0.34(1.189-0.2)+(1.189)^{2}]$
$\phi$=1.375
fcd=$\frac{250/1.1}{0.53+[0.53^{2}-0.2362^{2}]^{0.5}}$
fcd=225.2N/mm$^{2}$
pd=Ae$\times$fcd
6671$\times225.3$
=1.502$\times10^{6}$
=15.03$\times10^{3}N$
=1503KN
buckling about class b
$\lambda=0.34$
$\lambda y=\sqrt{\frac{fy\times(\frac{kl}{rmm})^{2}}{\Pi^{2}E}}$
$=\sqrt{\frac{250\times(2000/rmm)^{2}}{\Pi^{2}\times2\times10^{5}}}$
$\lambda y$=1.189
$\phi=0.5[1+0.34(1.189-0.2)+(1.189)^{2}]$
$\phi$=1.375
fcd=$\frac{250/11}{1.375+(1.375^{2}-1.189^{2})^{0.5}}$
fcd=110N/mm$^{2}$
pd=110$\times$6671
pd=733.7 KN
design load of column is 733.7 KN
$buckling \ \ z \ \ \ Class \ a$
$\alpha=0.21 \ \ \ \ class \ \ a$
$\frac{kl}{rxx} \ \ \ \ fcd$
20 $ \ \ \ \ $ 226
21$ \ \ \ \ $fcd
30$ \ \ \ \ $220
$\frac{30-20}{30-21}=\frac{220-223}{220-fcd}$
fcd=225.3 N/mm$^{2}$
buckling yy $ \ \ \ $ class b
$\frac{KL}{ryy} \ \ \ \ \ fcd$
100 $ \ \ \ \ $ 118
106 $ \ \ \ \ $ fcd
110 $ \ \ \ \ $ 104
fcd=110N/mm$^{2}$