u u Anal sis and Des Desii n of Com ress ession ion Mem Member berss (AISC 360-2005) developed by
Djoni Simanta
Bandung, 2008
Text Books: 1. Aghayere, A and Vigil, Jason. “Structural Steel Design A Practice- Oriented Approach” , Pearson International Edition, 2009
uc
ng n
om ompress on
. a. Flexural Buckling b. Torsional Buckling c. Flexural-Torsional Buckling 2. Element Local Buckling: a. Flange Local Buckling b. Web Local Buckling
em ers
1. Buckling in Compression Elements
If Boundary Conditions are known
Braced and Unbraced Frame
Assumptions
Braced Frame
Unbraced Frame
Notes
2. Local Buckling
Section B4 of the LRFD specification provide limiting values of Width-thickness ratios (denoted λ ) where shapes are classified as
o Noncompact o Slender
Slender Element Limits, λ r
b/t 0.56 E/Fy h/t w
1.49 E/Fy
b/t
0.56 E/Fy
b/t 0.56 E/Fy
b/t 0.45 E/Fy
d/t
b/t
h/t w
b/t
h/t w
1.40 E/Fy
1.49 E/Fy
b/t
1.40 E/Fy
0.75 E/Fy
0.56 E/Fy
1.49 E/Fy
t .
y
Slender Element Limits, λ r E
BJ34 BJ37 BJ41 BJ50 BJ55
Fy
Fy=210 MPa
Fy=240 MPa
Fy=250 MPa
Fy=290 MPa
Fy=410 MPa
0.45
13.89
12.99
12.73
11.82
9.94
0.56
17.28
16.17
15.84
14.71
12.37
.
.
.
.
.
.
1.40
43.20
40.41
39.60
36.77
30.92
1.49
45.98
43.01
42.14
39.13
32.91
BU KLIN
A E
Pro ile hape
Flexural Buckling
Any shape
Torsional Buckling
Double Symetric
Flexural-Torsional Buckling
Single Symetric, nsyme r c
Column Checking Procedure
Flexural Buckling
Torsional Buckling and Fl x r l-T r i n l B klin
Double Angle and Tee shape Compression Member Capacity Procedure
For Single Symetric Double Angle and Tee Shape Members : * Calculate critical flexural buckling stress due to non-symetrical axis,x, Fcrx. * Calculate Flexural buckling stress due to symetrical axis, y, Fcry from , * Calculate Flexural-torsional buckling stress due to symetrical axis, y, Fcr as function of (Fcry & Fcrz) * Choose Fcr=min(Fcrx, Fcr)
For All Other Cases Compression Member Capacity Outline Procedure 1. For Double Symetric Members : * Calculate critical flexural bucklin stress due to s metrical axis based on max. slenderness, Fcr1 * Calculate Torsional Buckling Stress, Fcr2 2. For Sin le S metric Members : * Calculate critical flexural buckling stress due to non-symetrical axis,x, Fcr1. * Calculate Flexural-torsional buckling stress due to symetrical axis, y, cr . 3. For Unsymetric Members : * Calculate flexural buckling stress due to principal axis, Fcr1. * Calculate flexural-torsional buckling stress, Fcr2.
