NASCC/ASCE Thursday May 13, 2010 Transforming Seismic Design in Low to Moderate Seismic Regions PDH #BN81C Session Chairs: Eric HinesCharlie Carter LeMessurierAISC.

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