written 5.7 years ago by |
20kN/m$^{3}$
2) thickness of Rcc slab is 120mm and top flang embedded in concrete having unit weight 25kN//m$^{3}$
3) L.L =3kN/m$^{2}$ and F.F.L=0.75kN/m$^{2}$
Given
1) thickness of brick wall=150mm
=0.15m
H=3m
$\int$ m=20kN/m$^{3}$
2) thickness of slab=120mm=0.120m
$\int c$=25kN/M$^{3}$
3) L.L =3kN/m$^{3}$
F.L=0.75kN/m$^{2}$
Assume weight of beam=1kN/m
load on beam b$_{1}$
Slab load
1) concrete load=25$\times$2$\times$0.12=6kN/m
2) F.F.L=0.75$\times$2=1.5kN/m
3) L.L=3$\times$2=6kN/m
Total slab load=13.5kN/m
factored slab load=13.5$\times1.5$=20.25kN/m
Wall load
Wall load=20$\times$3$\times0.15$ kN/m=6kN/m
factored load=9$\times$1.5=13.5kN/m
weight of beam $b_{1}$=1kN/m
factored weight of beam=1.5kN/m
Total load on beam b$_{1}$=20.25+13.5+1.5
=35.25kN/m
load on beam b1
load on beam b$_{2}$
load on beam b$_{2}$=13.5+1.5=15kN/m
1) V=$\frac{wl}{2}+\frac{2w}{2}$
=$\frac{15\times 6}{2}+\frac{2\times 10.5}{2}$
v=115.5kN
m=m max=208.5kN.m
2) Trial section
Zreq=$\frac{m.\gamma ma}{fy}$
=$\frac{208.5\times 10^{6}\times 1.1}{250}$
=917.4$\times$10$^{3}mm^{3}$
select ISWB 350 having Zp= 995.49$\times 10^{3}mm^{3}$
D=350 bf=200mm tf=114.4 mm
tw=8mm $\gamma_{1}$=12mm
Ze=887$\times 10^{3}mm^{3}$
Iz=15521.7$\times10^{4}mm^{4}$
d=D-2tf-2R1
=350-(2$\times 11.4)-(2\times 12)$
=303.2mm
3)selection classification
$\frac{b}{tf}=\frac{bfl2}{tf}=\frac{100}{11.4}$=8.77$\lt$9.4$\epsilon$
$\frac{d}{tw}=\frac{3036}{8}$=37.9$\lt$ 846
section is plastic
4) Vd=$\frac{Av\times fy}{\sqrt{3}\times \gamma mo}$
=$\frac{(350\times 8)\times 250)}{\sqrt{3}\times 1.1}$
Vd=367.41$\gt$ 113.5 safe
5) 0.6Vd=0.6$\times$ 367.41
=220.44v(115.5)$\lt$ Vd(220.44) low shear
Md=$\frac{Bd\ast ZP\ast fy}{\gamma mo}$ $\frac{1\times (99.549\times 10^{3})\times 250}{1.1}$
=226.25kN $\gt$ 208.5kN.m safe
$\lt$ 1.2$\times ze\ast \frac{fy}{\gamma mo}$
$\lt(1.2\times 887\times 10^{3})\ast \frac{250}{1.1}$
$\lt$ 241.91kN.m
(Ze=887$\times10^{3}mm^{3})$ safe
6) 1)$\frac{d}{tw}$=37.9$\lt $ 67$\epsilon$ no need to check shear buckling
2) web crippling
fwc=$\frac{(b_{!}+n_{2})+w\ast fy}{\gamma mo}$
b$_{1}$=75
n$_{2}$=2.5(tf+$\gamma _{!})$ =2.5(11.4+12)
=58.5
fwc=$\frac{(75+58.5)\ast 8\times 250}{1.1}$
=242.75kN $\gt$ 115.5kN safe
3) Deflection
Permissible =$\frac{span}{300}=\frac{6000}{300}$=20mm
$\int$act =$\frac{5}{384}$ $\frac{wl^{4}}{EI}+\frac{w_{2}\times a(3l^{2}-4a^{2})}{24EI}$
=$\frac{5(15/1.5)\times 6^{4}}{384(2\times 10^{5})\times (15521.7\times 10^{4})}$
=5.44mm
$\int $ act $\lt$ permissible safe again deflection