b) bearing strength of concrete =0.6$\times$fck =0.6$\times$15=9mpa

M15-fck=15

Required-welded gusseted base

1) AP=$\frac{pu}{0.6\times15}=\frac{1700\times10^{3}}{0.6\times 15}$

Ap=183.89$\times 10^{3}mm^{2}$

2) width of base plate(Bp)=350+2(16)

Bp=382mm

Assume gusset plate 16mm$\gt$tf

16mm$\gt$11.6 safe

overhange=$\frac{450-382}{2}$=34mm

Bp=350+2(16)+2(34)

Bp=450mm

3) Lb=$\frac{Ap}{Bp}=\frac{188.89\times10^{3}}{450}$=419.76mm

Lp=430mm

Step II. Thickness of base plate

Bmxx=$\frac{wl^{2}}{2}$ L=50 w= $\frac{pu}{AD}=\frac{1700\times 10^{3}}{450\times 436}$

W=8.885mpa

8.87$\lt0.6\times $fck

$\lt0.6\times$15

8.78$\lt 9$

MD=$zp\ast\frac{fy}{\gamma mo}$

$S\ast(Ze)\ast\frac{250}{3.1}$

10.98$\times 10^{3}=1.1085\ast(\frac{1\times t^{2}}{6})\ast\frac{250}{1.1}$t=16.18

t=16.18

t=18mm

Bm$\frac{wl^{2}}{8}=\frac{wl^{2}}{2}$

=$\frac{8.785\ast 350^{2}}{8}-\frac{8.785\ast50^{2}}{2}$

BM=183.85$\times10^{3}$Nmm

MD=S$\ast (\frac{1\ast t^{2}}{2}\ast\frac{250}{1.1})$

123.53$\times10^{3}=1.1085\times 1\times \frac{t^{2}}{6}\ast\frac{260}{1.1}$

t=54.74

Central partial has Bm in two section t=$\frac{54.25}{2}$-27.19

t=28mm

base plate=460$\times430\times18$

Connection assume 6mm fillet weld

Pd=(Lw)$\ast (E.T.T)+\frac{fu}{\sqrt{3}\ast \gamma me}$

$\frac{1700\times10^{3}}{2}=(Lw)+(0.7\times 16)\ast\frac{410}{\sqrt{3}\times1.25}$. Shop weld

Let=1068.70mm

Connection length of column flange with gusset plate available length of connection between column flange to gusset plate

(2$\times250)$+4(150)

=100mm

110$\gt$Lwreeq. Safe

Slant height of gusset plate

So=$\sqrt{90^{2}+90^{2}}$So=127.27

Permissible =o/s=13.6$\ast\epsilon\ast tg$

=217.6mm

Permissible o/s 2176$\gt$So. Provide

Safe