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NASCC/ASCE
Thursday May 13, 2010
Transforming Seismic Design
in Low to Moderate
Seismic Regions
PDH #BN81C
Session Chairs:
Eric Hines Charlie CarterLeMessurier AISC
Tufts University
988 km
Design Philosophy for Moderate Seismic Regions
Reserve Capacity – CBF
Ductility – EBF
Elastic Flexibility – MRF
Elastic Strength 988 km
Design Philosophy for Moderate Seismic Regions
Reserve Capacity – CBF
Ductility – EBF
Elastic Flexibility – MRF
Elastic Strength
Flexible reserve LFRSstabilizes structure(moderate ductility)
(b) Reserve capacity creates system ductility. Acceptable strength loss and required reserve ductility currently unknown.
3
1
2
(key parametersfor fundamentalunderstanding)
System Ductility
CBF
Stiff primary LFRS (CBF)fractures under MCE(no ductility)
(a) Whittaker et al. 1990
MRF as dualsystem
Design Philosophy for Moderate Seismic Regions
Reserve Capacity – CBF
Ductility – EBF
Elastic Flexibility – MRF
Elastic Strength
Design Philosophy for Moderate Seismic Regions
Reserve Capacity – CBF
Ductility – EBF
Elastic Flexibility – MRF
Elastic Strength
Design Philosophy for Moderate Seismic Regions
Reserve Capacity – CBF
Ductility – EBF
Elastic Flexibility – MRF
Elastic Strength
0 1 2 3Period, T (sec)
0.0
0.5
1.0
1.5
2.0
Spe
ctra
lAcc
eler
atio
n,S
a(g
)Atkinson & Boore (1995): 40 Motions
Median
2% in 50 UHS (2002)
Epistemic Bounds: COV = 0.5, +/- 1 SD
Bounds of 0.5 and 2.0
NASCC/ASCE
Thursday May 20, 2010
Eccentric Braced Frame
System Performance
Eric Hines Carlo JacobLeMessurier Tufts University
Tufts University
988 km
OCBF: V = 531k
EBF: V = 162 k (266k)
0.06
IBC 2006 (USGS 2002); MSBC 20082% in 50 year, Sa for T = 1.0s
988 km
OCBF: V = 531k
EBF: V = 162 k (266k)
0.06
IBC 2006 (USGS 2002); MSBC 20082% in 50 year, Sa for T = 1.0s
Category C:R = 3 NP for h > 65 ft
Category B:R = 3 NP for h > 100 ft
0 3 6 9 12 15 18 21Stories
0
300
600
900
1200
1500
1800
2100
2400
2700
Bas
eS
hear
(kip
s)
7th Edition, Massachusetts State Building Code(Based on ASCE 7-02 and -05)
1.6 Wind
1.0 EQ (R = 3, CBF, T = Ta)
1.0 EQ (R = 3, CBF, T = 1.7Ta)
1.0 EQ (R = 7, EBF, T = 1.7Ta)
Category C:R = 3 NP for h > 65 ft
Category B:R = 3 NP for h > 100 ft
0 3 6 9 12 15 18 21Stories
0
300
600
900
1200
1500
1800
2100
2400
2700
Bas
eS
hear
(kip
s)
7th Edition, Massachusetts State Building Code(Based on ASCE 7-02 and -05)
1.6 Wind
1.0 EQ (R = 3, CBF, T = Ta)
1.0 EQ (R = 3, CBF, T = 1.7Ta)
1.0 EQ (R = 7, EBF, T = 1.7Ta) System ATC 3-06(1984)
UCBRec.
UCBU.B.
BSSC(1988)
EBF R-Factors
System ATC 3-06(1984)
UCBRec.
UCBU.B.
BSSC(1988)
EBF R-Factors
Whittaker, Uang, Bertero (1987)Univ. California at Berkeley
EBF shake table test6-story 1/3 scale
4 6 8 10T im e (seconds)
-2.0
-1.0
0.0
1.0
2.0
Leve
l 2
-2.0
-1.0
0.0
1.0
2.0
Leve
l 3
-2.0
-1.0
0.0
1.0
2.0
Leve
l 4
-2.0
-1.0
0.0
1.0
2.0
Leve
l 5
-2.0
-1.0
0.0
1.0
2.0
Leve
l 6
-2.0
-1.0
0.0
1.0
2.0
Roo
f
U C B TestU C B M odel
UCB TestJacob Model
Hysteresis at Level 2 Link
4 6 8 10T im e (seconds)
-2.0
-1.0
0.0
1.0
2.0
Leve
l 2
-2.0
-1.0
0.0
1.0
2.0
Leve
l 3
-2.0
-1.0
0.0
1.0
2.0
Leve
l 4
-2.0
-1.0
0.0
1.0
2.0
Leve
l 5
-2.0
-1.0
0.0
1.0
2.0
Leve
l 6
-2.0
-1.0
0.0
1.0
2.0
Roo
f
U C B TestU C B M odel
UCB TestJacob Model
-0 .10 -0.05 0.00 0.05 0.10
Shear S tra in (radians)
-40
-20
0
20
40
Bra
ce V
ertic
al F
orce
(ki
ps)
-0 .10 -0.05 0.00 0.05 0.10
Hysteresis at Level 2 Link
Jacob UCB ModelJacob ASCE Model
-0 .10 -0.05 0.00 0.05 0.10
Shear S tra in (radians)
-40
-20
0
20
40
Bra
ce V
ertic
al F
orce
(ki
ps)
-0 .10 -0.05 0.00 0.05 0.10
4 6 8 10T im e (seconds)
-2.0
-1.0
0.0
1.0
2.0
Leve
l 2
-2.0
-1.0
0.0
1.0
2.0
Leve
l 3
-2.0
-1.0
0.0
1.0
2.0
Leve
l 4
-2.0
-1.0
0.0
1.0
2.0
Leve
l 5
-2.0
-1.0
0.0
1.0
2.0
Leve
l 6
-2.0
-1.0
0.0
1.0
2.0
Roo
f
ASC E m ode l
U C B M odel
-0 .10 -0.05 0.00 0.05 0.10
Ine lastic R ota tion (rad ians)
-40
-20
0
20
40
Leve
l 2
-0 .10 -0.05 0.00 0.05 0.10-40
-20
0
20
40-40
-20
0
20
40
Leve
l 3
-40
-20
0
20
40
Leve
l 4
-40
-20
0
20
40
Leve
l 5
-40
-20
0
20
40
Leve
l 6
-40
-20
0
20
40
Roo
f
-40
-20
0
20
40-40
-20
0
20
40-40
-20
0
20
40
Link
She
ar F
orce
(ki
ps)
-40
-20
0
20
40-40
-20
0
20
40A SC E M odelU C B M odel
Jacob UCB ModelJacob ASCE Model
4 6 8 10T im e (seconds)
-2.0
-1.0
0.0
1.0
2.0
Leve
l 2
-2.0
-1.0
0.0
1.0
2.0
Leve
l 3
-2.0
-1.0
0.0
1.0
2.0
Leve
l 4
-2.0
-1.0
0.0
1.0
2.0
Leve
l 5
-2.0
-1.0
0.0
1.0
2.0
Leve
l 6
-2.0
-1.0
0.0
1.0
2.0
Roo
f
ASC E m ode l
U C B M odel
-0 .10 -0.05 0.00 0.05 0.10
Ine lastic R ota tion (rad ians)
-40
-20
0
20
40
Leve
l 2
-0 .10 -0.05 0.00 0.05 0.10-40
-20
0
20
40-40
-20
0
20
40
Leve
l 3
-40
-20
0
20
40
Leve
l 4
-40
-20
0
20
40
Leve
l 5
-40
-20
0
20
40
Leve
l 6
-40
-20
0
20
40
Roo
f
-40
-20
0
20
40-40
-20
0
20
40-40
-20
0
20
40
Link
She
ar F
orce
(ki
ps)
-40
-20
0
20
40-40
-20
0
20
40A SC E M odelU C B M odel
5 @ 30’-0” = 150’-0”
Design loadwith 0%Eccentricity
1’ slab overhangin each direction
13’Ty
p.
18’
30’-0” 30’-0” 30’-0”
5 @
30’-0” =
15
0’-0”
Chevron Bracing (Typ.)CBF (left) or EBF (right)
W16x26 (Typ.)
W21x44 (Typ.)
W16x36 (Typ.)
W21x44 (Typ.)
9-Story Prototype
5 @ 30’-0” = 150’-0”
Design loadwith 0%Eccentricity
1’ slab overhangin each direction
13’Ty
p.
18’
30’-0” 30’-0” 30’-0”
5 @
30’-0” =
15
0’-0”
Chevron Bracing (Typ.)CBF (left) or EBF (right)
W16x26 (Typ.)
W21x44 (Typ.)
W16x36 (Typ.)
W21x44 (Typ.)
0 1 2 3 4 5 6 7 8 9 10
Scale Factor
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0P
rob
abili
ty
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
Pro
bab
ility
0 1 2 3 4 5 6 7 8 9 10
Scale Factor
Up to 72” Linksmax = 0.02 rad
Up to 72” Linksmax = 0.41 rad
9-Story Prototype
0 1 2 3 4 5 6 7 8 9 10
Scale Factor
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0P
rob
abili
ty
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
Pro
bab
ility
0 1 2 3 4 5 6 7 8 9 10
Scale Factor
Up to 72” Linksmax = 0.02 rad
Up to 72” Linksmax = 0.41 rad
0 1 2 3 4 5 6 7 8 9 10
Scale Factor
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
Pro
bab
ility
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
Pro
bab
ility
0 1 2 3 4 5 6 7 8 9 10
Scale Factor
Up to 48” Linksmax = 0.02 rad
Up to 48” Linksmax = 0.41 rad
0 1 2 3 4 5 6 7 8 9 10
Scale Factor
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
Pro
bab
ility
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
Pro
bab
ility
0 1 2 3 4 5 6 7 8 9 10
Scale Factor
Up to 24” Linksmax = 0.80 rad
Up to 24” Linksmax = 0.81 rad
0 1 2 3 4 5 6 7 8 9 10
Scale Factor
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
Pro
bab
ility
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
Pro
bab
ility
0 1 2 3 4 5 6 7 8 9 10
Scale Factor
Up to 48” Linksmax = 0.02 rad
Up to 48” Linksmax = 0.41 rad
0 1 2 3 4 5 6 7 8 9 10
Scale Factor
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
Pro
bab
ility
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
Pro
bab
ility
0 1 2 3 4 5 6 7 8 9 10
Scale Factor
Up to 24” Linksmax = 0.80 rad
Up to 24” Linksmax = 0.81 rad
72” 48” 24”
Pu/Pn 0.89 0.89 1.05
GM 7 8 10
Scale 2.7 2.7 3.7
0.73
Column Axial Loads1.2D + 0.5L + 1.0E
72” 48” 24”
Pu/Pn 0.89 0.89 1.05
GM 7 8 10
Scale 2.7 2.7 3.7
0.73
Column Axial Loads1.2D + 0.5L + 1.0E
0.73
0.73
0.73