written 5.7 years ago by |
Given
ISMB 250
bf=125m tf=12.5m tw=6.9
$\gamma$1=13m
ISHB 200 at 37.92 bf=200mm tf=9mm
tw=6.1mm
R=85kN(factored load)
$\phi$ of bolt=16mm
Anb=157mm$^{2}$
fub=4$\times$100=400N/mm$^{2}$
fy=250N/mm$^{2}$
fu=410N/mm$^{2}$
required no of bolts
shearing capacity of bolt =$\frac{fub\times Anb\times nn}{\sqrt{3}\times\gamma mb}$
=$\frac{400\times 157\times 1}{\sqrt{3}\times 1.25}$
Vdsb=29kN
bearing capacity of bolt=2$\times$K$\times$t$\times$d$\times$fu
Kb=$(\frac{e}{3d0},\frac{p}{3d0}-1, \frac{fyb}{fu},1)$ min value
Vdpb=2$\times0.56\times9\times16\times 410$
Vdps=66.129kN
No .of bolts=$\frac{factored \ load}{bolt \ value}$ (min value Vdsb & Vdpb)
=$\frac{85}{29}$=2.39$\approx$4Nos
Shear capacity of seat angle
=$\frac{bf}{\sqrt{3}\times ymo}$
=$\frac{125\times 10\times 250}{\sqrt{3}\times 1.1}$
=164$\gt$35
Step II length of angle supporting beam(b)=125mm
Step III bearing length of route line of beam(b)
(b)=$\frac{R}{\frac{tw\times fyh}{ymo}}$==$\frac{80}{\frac{6.9\times250}{1.1}}$=54.2mm
b=54.2mm
Step IV length of out standing leg=54.2+10=64.2
Assume 75mm
provide 150$\times75\times$10
b1=b-(tf-$\gamma$1)
=54.2-(12.5+13)
b1=28.7mm
b2=(b1+10)-ta-$\gamma$2
=(28.7+10)-10-10
b2=18.7mm
Step V bending moment of root angle =$\frac{R}{b1}\times b2\times\frac{b2}{2}$
=$\frac{85}{28.7}\times18.7\times \frac{18.7}{2}$
mu=517.83kN/mm
Step VI
moment resisting capacity
md=1.2$\times\frac{250}{1.1}\times \frac{12.5\times10^{3}}{6}$
md=568.18kN.mm
md$\gt$mu hence safe
Step VIII Shear strength of beam
Vd=$\frac{aw\times fyw}{\sqrt{3}\times ymo}$=$\frac{250\times6.9)\times 250}{\sqrt{3}\times1.1}$
Vd=226.35