The 5th Tongji-UBC Symposium on Earthquake Engineering
“Facing Earthquake Challenges Together” May 4-8 2015, Tongji University, Shanghai, China
Performance Assessment of Buckling
Restrained Knee Braced Truss Moment
Frame (BRKBTMF) System
Yuanjie Li
MASc | The University of British Columbia, Canada
Supervised by Tony Yang, Ph.D.
Introduction
Resilient long-span seismic system

Long-span truss

Buckling restrained brace (BRB)
2
Buckling restrained knee braced truss moment frame
(BRKBTMF)
3@13'=39'
14'
4 bays @ 30'=120'
Univ. of
Michigan
King Mongkut’s
Univ. of Tech.
IIT, Kanpur
3
Design procedure
Performance-based plastic design procedure
Wn
Wn
Wn
-
Pbrb : BRB com
+
forces
Pw -Pw PwPbrbPw: BRB
Pw compression
Fi = iVy
Wi
Pbrb : BRB tensi
+ compression forces
Pw Pwhn Pw Pw PPwbrb : BRB
Fi = iVy
Wi
Pbrb : BRB tension forces
+
PTr. : Trusses fo
Fi = iVy
hn Pw Pw Pw Pw Pw+
Wi
Pbrb : BRB tension forces
Pbrbforces
PTr. : Trusses
Pbrb
hi
hn
Pc : Concentra
+
PTr. P:brbTrusses
forces
p
Pbrb
hi +
Pc : Concentrated loads
from
orthogona
y
V
Pbrb Pc : Concentrated
p
Pbrb
hi
loadsgravity
from beams
orthogonal
Pw : Gravity lo
Vy
p
orthogonal gravity beams
(a)
(b)
Pw : Gravity loads
Vy
Fi : Equivalen
(a)
(b)
Pw : Gravity loads
Fi : Equivalent lateral forces
(a)
(b)
Fi : Equivalent lateral forces
Fi
Fi
Pc
Fi
Pc
PTr.
PTr.
+
brb
P
PTr.
PTr.
+
brb
P
Pc
PTr.
PTr.
Pc
PTr.
PTr.
PPc Tr.
PTr.
PTr.
PTr.
+
PTr.
PPbrbTr. Pbrb
- Int. Col.
+
Pbrb Pbrb
+
Pbrb
Pc
PTr.
PTr.
-
Pbrb
Ext. Col.
Int. Col.(c)
Ext. Col.
Int.
Ext. Col.
(c)Col.
(c)
4
P
Seismic performance evaluation
Prototype building

30 ft.
6 bays @ 9.1 m (30 ft.)

45 ft.
4 bays @ 13.7 m (45 ft.)

60 ft.
3 bays @ 18.3 m (60 ft.)
N
E
4 bays @ 9.1 m (30 ft.)
D
C
B
A
9.1 m (30 ft.)
Gravity Truss/Beam
13.7 m (45 ft.)
13.7 m (45 ft.)
9.1 m (30 ft.)
Gravity
Truss/Beam
BRKBTMF/MF
BRKBTMF/MF
Seismic force resisting system(BRKBTMF/MF)

18.3 m (60 ft.)
Gravity Truss
18.3 m (60 ft.)
BRKBTMF/MF
Plan view
5
Prototype building
6 bays @ 9.1 m (30 ft.)
6 bays @ 9.1 m (30 ft.)
4 bays @ 13.7 m (45 ft.)
4 bays @ 13.7 m (45 ft.)
4 bays @ 13.7 m (45 ft.)
3 bays @ 18.3 m (60 ft.)
3 bays @ 18.3 m (60 ft.)
6 bays @ 9.1 m (30 ft.)
4 bays @ 13.7 m (45 ft.)
4 bays @ 13.7 m (45 ft.)
3 bays @ 18.3 m (60 ft.)
3 bays @ 18.3 m (60 ft.)
60 ft.

4 bays @ 13.7 m (45 ft.)
45 ft.

6 bays @ 9.1 m (30 ft.)
3 bays @ 18.3 m (60 ft.)
3 bays @ 18.3 m (60 ft.)
6
Moment frame (MF)
3.96 m 4.27 m
3 @m
3 @ 3.96
m
4.11
@
3
m 4.57 m
4.23
@
3
m
4.11
@
3
m
4.27
m
m
4.23
@
3
4.57
m
3 @m3.964.27
m
4.42
m
4.42
m
4.11
@
3
m
4.23
@
3
4.57
m
4.42
ft.) ft.)
ft.) ft.) (14
ft.)(14
(14(13
(13 ft.)(13 ft.)
ft.) ft.)(14.5 (14
(13.5
ft.)ft.) (15 ft.)
(13.5
ft.)(15
(15(14
ft.) ft.)(14 ft.)
ft.)
(14.5
(13.5 ft.)
(14.5
6 bays @ 9.1 m (30 ft.)
6 bays @ 9.1 m (30 ft.)
m
m
m m 4.88 m
3.96
@m
@ 4.34
@ 4.72
3m
m4.65mm 34.65
m4.88
4.88
@ 4.34
@ 4.72
3 @ 3.96
4.27mm 34.27
m
3 @m3.964.27
3 @m4.3434.65
3 @m4.723m
ft.)(14.25
(15.25
ft.)
ft.) ft.) (14
(14.25
ft.)ft.) ft.)
ft.)(14
(14(13
(16 ft.)
ft.) (15.25
ft.)
(13 ft.)(13 ft.)
(14.25
(15.5ft.)
(15.25
(16 ft.) (16 ft.)
ft.)
(15.5 ft.)(15.5
MF
BRKBTMF

BRKBTMF

MF
BRKBTMF
MF
30 ft.

BRKBTMF
Seismic performance evaluation
Initial cost comparison
$6,000,000

MF
$5,000,000
$4,000,000
$3,000,000
$2,000,000

BRKBTMF
Deck
Gravity Columns
Gravity Truss/Beam
$1,000,000
Seismic Columns
Seismic Truss/Beam
$0
BRB
7
Seismic performance evaluation
Ground motion and experimental calibration
(a) Target spectra
for three hazard
(b) Ground motions
scaling for 2%/50 years
2.5
1.5
Normalized Moment M/My [-]
Normalized Stress  / y [-]
2
1.5
1
0.5
0
-0.5
1
0.5
0
-0.5
-1
-1.5
Experimental
Simulation
-2
-2.5
-2.5 -2 -1.5 -1 -0.5
0
0.5
1
1.5
2
2.5
Brace Strain [%]
(c) Normalized BRB
stress-strain response
-1
-1.5
-0.06
Experimental
Simulation
-0.04
-0.02
0
0.02
0.04
0.06
Total Rotation [rad]
(d) Moment-rotation response
8
Element removal procedure
9
Seismic performance evaluation
Dynamic performance study
10
Dynamic performance study
Median inter-story drift response
11
Dynamic performance study
Median floor acceleration response
12
Seismic performance evaluation
Earthquake financial impact study
Building Services
Architect. Comp.
Structural Comp.
Occupants
Contents
13
Building performance groups
14
Component fragility data
15
Cumulative distribution function
16
Conclusion
o Buckling Restrained Knee Brace Truss Moment Frame
(BRKBTMF):
o Lower initial cost:
o Not significantly affected by the architecture
layout.
o Higher structural performance:
o Lower structural demand (floor acceleration and
ISD).
o Lower repair cost and downtime.
17
Future research
Test setup
Specimen drawing
Acknowledgement to:
Tony Yang (University of British Columbia),
Subhash C. Goel (University of Michigan),
S. Leelataviwat (King Mongkut’s University of Technology).
18
Thank you!
Certificate of Structural
Engineering Program
19