Experiments and Simulations of an
Innovative Performance
Enhancement Technique for Steel
Building Beam-Column Connections
Machel Morrison
Doug Schweizer
Tasnim Hassan (PI)
Post Northridge Research
Bolted Extended Endplate
Bolted Flange Plate
AISC 341 Performance Criteria
θd =0.04 Radians
Kaiser Bolted Bracket
Figures from Hamburger et. al 2009
WUF-W
Reduced Beam Section
Heat Treated Beam Section (HBS)
Mf ∝ MRBS
Mf ∝ MHBS
Heat Treated Beam Section (HBS)
80
Uniaxial Tension Stress-Strain Response (A992)
σx (ksi)
70
Slow Cool
60
50
700 C
Temp ˚C
Unconditioned
40
30
Air Cool
800 C
20
1050 C
1050 C Slower cooling
rate
10
Figure from :http://textbooks.elsevier.com
0
0%
10%
Time (min)
20%
30%
εx (%)
40%
50%
60%
Induction Heating
- Eddy currents “induced”
by alternating magnetic
field
Advantages:
•Lower energy Input
than traditional heating
sources
Induction heating provided by Ameritherm Inc.
•Easy to localize heat
input
Induction Heating
Challenges:
-Difficult to control
temperature uniformity
-Prescribed slow
cooling rate was not
achieved
Experimental Program
-4 Full Scale WUF-W
-3 HBS and 1 Unconditioned
-Sub assemblage similar
to Engelhardt et al 1998DB5
Experiment Results
HBS -Cyclic
Response
Cyclic Response
of HBS
& WUF-W
40 40000
M
(x 1000 in-Kip)
Moment (in-Kip)
30 20000
0
20
WUF-W
HBS
-20000
10
-40000
-0.06
0
0
-0.04
-0.02
5E-17
0
0.02
Interstory
0.02
0.04
Drift θ 0.04
(radians)
Interstory Drift θ (radians)
0.06
0.06
Experiment Results
WUF-W
HBS
HBS
Experiment Results
WUF-W
HBS
Challenges
Uniaxial Tension Stress-Strain
Response (A992)
80
-Significant yielding spread
beyond HBS region and
higher moments than
expected
σx (ksi)
60
40
Unconditioned
Induction Heat treated
20
Furnace Heat treated
0
0
0.1
0.2
εx (in/in)
0.3
0.4
0.5
FE Simulations
ANSYS 12.1 Mechanical
ADPL
-Quadratic Shell Elements
-Finite Strain, Large Displacement Formulation
-Initial Geometric Imperfections (Flange thickness variation, out of
straightness)
FE Simulation- Constitutive Model
80
σx (ksi) (Chaboche 1986)
-Non Linear Kinematic Hardening Model
A572
Gr 50
A992
Beam
Flange
80
σx (ksi)
3
60
60
f ( s  a )  [ ( s  a )  ( s  a )]1 2   o  0
2
d
-0.05
-1.5
p
40
f
 d

-0.04
-1
-0.03
4
d a   d ai
i 1
-0.02
-0.5
20
Yield Surface
40
20
Flow Rule
0
-0.01
0
0
0
0.01
0.5
0.02
0.03
1
Chaboche Kinematic εx (%)
-40
Hardening
Rule
-20
-20
0.04
1.5
-40
2
p
p
d a i  Ci d    i ai d 
3
Experiment results from
-60
0.05
εx (in/in)
Experiment
Chaboche Model
Chaboche Model
-60
-80
-80
Kaufmann et. al 2001
Experiment
Validation of FE Simulation
Cyclic Response of HBS
WUF-W
40
40
M
M
(x1000 in-Kip)
(x 1000 in-Kip)
20
-0.05
-0.05
-0.03 -0.03
-0.01
0
-0.01
-20
20
0
0.01
-20
0.01
0.03
0.03 0.05
θ
0.05
θ
WUF-W Expt Response
HBS Experiment
Response
WUF-F
Simulation
(Chaboche)
HBS Simulation
-40
-40
Validation of FE Simulation
Strain Profiles
1500
WUF-W
εx (microstrain)
1000
Tension Flange
0.005 Rads
500
0.00375 Rads
Position along flange (in.)
0
-5
-3
-1
1
Compression Flange
-500
3
5
0.00375 Rads
Experiment
Simulation
-1000
0.005 Rads
0.0075 Rads
-1500
FE Simulation Results
0.05
εpx (%)
0.01 Rads
Position along Flange (in)
0.00
-6
-4
0.02 Rads
-2
0
2
4
-0.05
-0.10
-0.15
0.03 Rads
Furnace HT Properties
Induction HT Properties
-0.20
-0.25
Compression Flange
-0.30
6
Expt Results- Flange Buckling
HBS
WUF-W
Validation of FE Simulation
FE Results- Flange Buckling
1.5
Local Flange Buckling WUF-W
δ (in)
1.0
0.5
0.0
0
5
10
15
20
25
30
Distance from Column Face (in)
-0.5
-1.0
WUF-W Simulation
WUF-W Experiment Results
-1.5
-2.0
FE Results- Flange Buckling
Shear tab w/Supplemental Weld
No Shear
tab/Supplement weld
FE Results- Flange Buckling
1.5
Local Flange Buckling WUF-W
δ (in)
1.0
0.5
0.0
0
5
10
15
20
25
30
Distance from Column Face (in)
-0.5
-1.0
WUF-W Simulation
-1.5
WUF-W Experiment Results
-2.0
WUF-W Simulation (No Shear Tab/
Supplemental Weld)
FE Results –Flange Buckling
Shear tab w/Supplemental Weld
10
No shear tab/Supplemental weld
ε
10
ε
px (%)
px (%)
5
0.04 rads
5
Position along
flange (in.)
0
0
-6
-4
-2
0
2
4
0.02 rads
0.03 rads
Position along
flange (in.)
-5
6 -6
0.02
rads
-4
-2
0.03
rads
0
-5
2
4
6
0.035
rads
-10
-10
Compression Flange
Compression Flange
-15
-15
WUF-W
WUF-W
-20
-20
-25
-25
Ricles et. al 2002
0.04
rads
Summary
-Heat treatment of beam flanges reduces strength of steel and
initiates yielding in the heat treated regions
-Uniform heat pattern difficult to achieve with Induction
heating, σ-ε response varied from furnace heat
treatment
-Heavy shear w/supplemental fillet weld to beam web influences
local flange buckling
-Future experiments are being planned with new heat treatment
technique
Acknowledgments
-National Science Foundation (NSF)
-Network for Earthquake Engineering Simulation (NEES)
-MAST LAB @ U of Minnesota
-Lejune Steel Company
-Ameritherm Inc.
New Heat treatment Technique
Uniaxial Tension Stress-Strain Response (A992)
80
σx (ksi)
60
40
Unconditioned
Induction Heat treated
20
New Heat treatment Method
0
0
0.1
0.2
εx (in/in)
0.3
0.4
0.5
0.6
COMPARISON WUF-W, HBS & RBS
WUF-W No Shear
tab/Supplemental
weld
HBS No Shear
tab/Supplemental
weld
RBS No Shear
tab/Supplemental
weld
COMPARISON WUF-W, HBS & RBS
WUF-W
From Hassan and Syed 2009
Moment Response
Cyclic Response of WUF-W
40
M
(x 1000 in-kip)
20
0
-0.05
-0.03
-0.01
0.01
0.03
θ
0.05
WUF-W
-20
WUF-W Simulation
(Multilinear)
-40
Moment Response
Cyclic Response of HBS & WUF-W
40
M
(x 1000 in-Kip)
30
WUF-W Expt
20
WUF-W Simulation
HBS Expt
HBS Simualtion Induction HT
10
HBS Simulation Improved HT
0
0
0.02
0.04
Interstory Drift θ (rad)
0.06