Contents IS 800 2007 Example 001

User Manual: IS 800-2007 Example 001

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IS 800-2007 Example 001
WIDE FLANGE MEMBER UNDER COMPRESSION
EXAMPLE DESCRIPTION
The frame object axial strengths are tested in this example.
A continuous column is subjected to factored load N = 1 kN. This example was
tested using the Indian IS 800:2007 steel frame design code. The design
capacities are compared with independent hand calculated results.
GEOMETRY, PROPERTIES AND LOADING
L = 3m
TECHNICAL FEATURES TESTED
Section compactness check (column)
Member compression capacity
Material Properties
E = 200x103 MPa
v = 0.3
G = 76923 MPa
Loading
N = 1 kN
Design Properties
f
y
= 250 MPa
fu = 410 MPa
Section: ISMB 350
Ed
L
A
A
Section A-A
IS 800-2007 Example 001 - 1
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RESULTS COMPARISON
Independent results are taken from hand calculations based on the CSI steel
design documentation contained in the file “SFD-IS-800-2007.pdf,” which is
available through the program “Help” menu. The example was taken from
Example 9.2 on pp. 765-766 in “Design of Steel Structures” by N. Subramanian.
Output Parameter
ETABS
Independent
Percent
Difference
Compactness Plastic Plastic 0.00%
Design Axial Strength, Ncrd 733.85 734.07 -0.03%
COMPUTER FILE: IS 800-2007 EX001
CONCLUSION
The results show an acceptable comparison with the independent results.
IS 800-2007 Example 001 - 2
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HAND CALCULATION
Properties:
Material: Fe 250
E = 200,000 MPa
fy = 250 MPa
Section: ISMB 350
A = 6670 mm2
b = 140 mm, tf = 14.2 mm, d = 350 mm, tw = 8.1 mm, r = 1.8 mm
( )
( )
2 350 2 14.2 1.8 318mm
f
hd t r=− += − + =
ry = 28.4 mm, rz = 143 mm
Member:
KLy = KLz = 3,000 mm (unbraced length)
0
1.1
M
γ=
Loadings:
1kN
Ed
N=
Section Compactness:
250 250 1
250
y
f
ε= = =
Localized Buckling for Flange:
8.4 8.4 1 8.4
p
λ = ε= • =
70 4.93
14.2
e
f
b
t
λ= = =
4.93 8.40
ep
λ = <λ =
So Flange is Plastic in compression
IS 800-2007 Example 001 - 3
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Localized Buckling for Web:
/ & 42 42
ps
NAλ = λ = ε=
for compression
318 39.26
8.1
e
w
d
t
λ= = =
39.26 42
es
λ= <λ=
So Web is Plastic in compression
Since Flange & Web are Plastic, Section is Plastic.
Member Compression Capacity:
Non-Dimensional Slenderness Ratio:
350 2.5 1.2
140
f
h
b= = >
and
14.2mm 40mm
f
t= <
So we should use the Buckling Curve ‘a’ for the z-z axis and Buckling Curve ‘b’
for the y-y axis (IS 7.1.1, 7.1.2.1, Table 7).
Z-Z Axis Parameters:
For buckling curve a,
0.21α=
(IS 7.1.1, 7.1.2.1, Table 7)
Euler Buckling Stress:
22
22
200,000 4485MPa
3,000
143
cc
zz
z
E
fKL
r
ππ
= = =
 




250 0.2361
4485
y
z
cc
f
f
λ= = =
IS 800-2007 Example 001 - 4
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( ) ( )
22
0.5 1 0.2 0.5 1 0.21 0.2361 0.2 0.2361
 
φ= +α λ− +λ = + − +
 
0.532φ=
Stress Reduction Factor:
22 2 2
11
0.9920
0.532 0.532 0.2361
χ= = =
φ+ φ −λ + −
,
0
250
0.992 255.5MPa
1.1
y
cd z
M
f
f=χ= •=
γ
Y-Y Axis Parameters:
For buckling curve b,
0.34α=
(IS 7.1.1, 7.1.2.1, Table 7)
Euler Buckling Stress:
22
22
200,000 177MPa
3,000
28.4
cc
zz
z
E
fKL
r
ππ
= = =
 




250 1.189
177
y
y
cc
f
f
λ= = =
( ) ( )
22
0.5 1 0.2 0.5 1 0.34 1.189 0.2 1.189
 
φ= +α λ− +λ = + − +
 
1.375
φ=
Stress Reduction Factor:
22 2 2
11
0.4842
1.375 1.375 1.189
χ= = =
φ+ φ −λ + −
,
0
250
0.4842 110.1MPa
1.1
y
cd y
M
f
f=χ= •=
γ
Governs
,
6670 110.1
d cd y
P Af= = •
734.07kN
d
P=
IS 800-2007 Example 001 - 5

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