8/12/2012

1

STEEL PLATE SHEAR WALLS (SPSW), TEBF, CFST, SF,

AND OTHER SHORT STORIES

Michel Bruneau, Ph.D., P.EngProfessor

Department of Civil, Structural, and Environmental Engineering

Introduction

Focus on SPSW (incl. P-SPSW, SC-SPSW), CFST, CFDST (and maybe a bit more)Broad overview (References provided in NASCC paper for more in-depth study of specific topics)Additional technical information can also be found at www.michelbruneau.com and in “Ductile Design of Steel Structures, 2nd Edition” (Bruneau et al. 2011)*.

* Subliminal message: This book will give you ultimate reading pleasure –buy 100 copies now!

Acknowledgments - 1Graduate students:

Samer El-Bahey (Stevenson & Associates)Jeffrey Berman (University of Washington, Seattle)Daniel Dowden (Ph.D. Candidate, University at Buffalo)Pierre Fouche (Ph.D. Candidate, University at Buffalo)Shuichi Fujikura (ARUP)Michael Pollino (Case Western Reserve University)Ronny Purba (Ph.D. Candidate, University at Buffalo)Bing Qu (California Polytechnic State University)Ramiro Vargas (Technological University of Panama)Darren Vian (Parsons Brinkerhoff)

Acknowledgments - 2Sponsors:

National Science Foundation (EERC and NEES Programs)New York StateFederal Highway Administration,American Institute of Steel ConstructionEngineer Research and Development Center (ERDC) of the U.S. Army Corps of EngineersMCEER, NCREE, Star Seismic, and Corus Steel.See others at www.michelbruneau.com

This support is sincerely appreciated. Opinions presented are those of the author.

Steel Plate Shear Walls Steel Plate Shear Walls (SPSW)(SPSW)( )( )

Example of Example of ImplementationImplementation(USA)(USA)

CourtesyTony Harasimowicz, KPFF, Oregon Beam (HBE)

Column (VBE)

Infill (Web)

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2

Examples of ImplementationExamples of Implementation(USA)(USA)

LA Live56 stories

Courtesy Lee Decker – Herrick Corporation, Stockton, CA

Examples of ImplementationExamples of Implementation(USA)(USA)

Courtesy of GFDS Engineers, San Francisco, and Matthew Eatherton, Virginia Tech

Analogy to TensionAnalogy to Tension--only only Braced FrameBraced Frame

Flat bar braceVery large brace

l d ( i

V

slenderness (e.g. in excess of 200)

Pinched hysteretic curvesIncreasing drift to dissipate further hysteretic energyNot permitted by Not permitted by AISC Seismic ProvisionsPermitted by CSA-S16 within specific limits of application

Analogy to TensionAnalogy to Tension--only only Braced FrameBraced Frame

Steps to “transform” into a SPSW1) Replace braces by

V) p y

infill plate (like adding braces)

Anchor Beam

Analogy to TensionAnalogy to Tension--only only Braced FrameBraced Frame

Steps to “transform” into a SPSW1) Replace braces by

V) p y

infill plate (like adding braces)2) For best seismic performance, fully welded beam-column connections

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3

EndEnd--ResultResult

Cyclic (Seismic) behavior of SPSWSum of

V

Fuller hysteresis provided by moment connectionsStiffness and redundancy provided by infill plate

Berman/Bruneau June 12 2002 TestBerman/Bruneau June 12 2002 Test

L/tw = 3740h/L = 0.5(centerline

dimensions)

Example of Structural FuseExample of Structural Fuse

-3 -2 -1 0 1 2 3Drift (%)

-600

-400

-200

0

200

400

600

Bas

e S

hear

(kN

)

Specimen F2Boundary Frame

600 Drift (%)

-3 -2 -1 0 1 2 3Drift (%)

-600

-400

-200

0

200

400

Base

She

ar (k

N)

Forces from Diagonal Tension FieldForces from Diagonal Tension FieldωV = σ t cos2(α)ωH = σ t sin(α) cos(α) = ½ σ t sin(2α)FH = ωH L = ½ σ L t sin(2α)

σ ·t

α P = σ · t · ds ·cos

α

PANEL TENSION FIELD STRESS ACROSS UNIT

DIAGONAL WIDTH, σ

Knowing L, σy, and α,Can calculate needed thickness (t)

α

dx UNIT LENGTH ALONG BEAM

UNIT PANEL WIDTH ALONG DIAGONAL

P = σ · t · ds

V =

P·

ωH =H /dx

ωV =V /dx

SPSW HBE

ds

H =P·sin α

RESULTANT TENSION FIELD FORCE, P AND COMPONENTS

SPSW WEB PLATE

HORIZONTAL, ωH, AND

VERTICAL, ωV, DISTRIBUTED LOADING

θ

α

Brace and Strip ModelsBrace and Strip Models

Equivalent Brace Model (Optional)

hs

L

hs

L

Strip Model

i

iiiiw L

Atα

θθ=

2sin2sinsin2

2

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Strip ModelStrip ModelDeveloped by Thorburn, Kulak, and Montgomery (1983), refined by Timler and Kulak (1983))V ifi d i t ll b Verified experimentally by

Elgaaly et al. (1993)Driver et al. (1997)Many others

Strips models Strips models in in retrofit project retrofit project using steel plate shear wallsusing steel plate shear walls

Courtesy of Jay Love, Degenkolb Engineers

AISC Guide Design of SPSWAISC Guide Design of SPSW(Sabelli and Bruneau (Sabelli and Bruneau 20062006))

Review of implementations to dateReview of research resultsDesign requirements and processDesign examples

Region of moderate seismicityRegion of high seismicity

Other design considerations (openings, etc.)

Recent Observations on SPSWRecent Observations on SPSW((BruneauBruneau et al. 2011)et al. 2011)

Capacity design from Plastic Analysis

Demands on VBEsFlexibility Factor’s purposeFlexibility Factor s purpose

Demands on HBEsHBE in-span yieldingRBS connections in HBEs

P-SPSW (reduced demands)Repair and drift demands

Plastic Analysis ApproachPlastic Analysis Approach

Yielding stripsPlastic Hinges

For designstrength, neglectplastic hingescontribution

hM

LtFV py

⋅+⋅⋅⋅⋅=

42sin

21 α

Used to develop Free Body Diagrams of VBEs and HBEsof VBEs and HBEs

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Capacity Design of VBECapacity Design of VBE Capacity Design of VBECapacity Design of VBE

Importance of Importance of Capacity DesignCapacity Design

SPSW-4 UBC Test (Lubell et al. 2000)

Lubell et al. (2000) observed poor behavior of some SPSWs (pull-in of columns)Others suggested

Flexibility Limit IssueFlexibility Limit Issue

Others suggested flexibility limit desirable to prevent slender VBEs

SPSW-2 UBC Test (Lubell et al. 2000)

Plate girder analogy

δ

L

o

ηu

ηo

u

o

xα

Flexibility factor

Infill PanelStiffner

Flexibility Limit (cont’d)Flexibility Limit (cont’d)

hsxu V

Flange can be modeled as a continuous beam on elastic foundation

40.72

wit si

c

thI L

ω =

( ) 2max

sin cosh cos sinh2 2 2 21

sin sin cos sinh cosh2 2 2 2

t t t t

gu o

t t t t

Lω ω ω ω

εη η

ω ω ω ωα

⎛ ⎞⎛ ⎞ ⎛ ⎞ ⎛ ⎞ ⎛ ⎞+⎜ ⎟ ⎜ ⎟ ⎜ ⎟ ⎜ ⎟⎜ ⎟⎝ ⎠ ⎝ ⎠ ⎝ ⎠ ⎝ ⎠⎜ ⎟− = −⎛ ⎞ ⎛ ⎞ ⎛ ⎞ ⎛ ⎞⎜ ⎟+⎜ ⎟ ⎜ ⎟ ⎜ ⎟ ⎜ ⎟⎜ ⎟⎝ ⎠ ⎝ ⎠ ⎝ ⎠ ⎝ ⎠⎝ ⎠

where

Infill Panel

Steel Plate Shear Wall Plate Girder

I-Beam Plate Girder

Flange

UBC SPSW-2 and SPSW-4: 3.35tω =Other specimens that behaved well:

2.5tω ≤

40.7 2.52

wit si

c

thI L

ω = ≤

Empirically based flexibility limit:

0 7

0.8

0.9

1.0

ess

Flexibility Limit (cont’d)Flexibility Limit (cont’d)

40.00307 wi sic

t hIL

≥

Introduced in the CAN/CSA S16-01 and 2005 AISC Seismic Provisions

Solving

0 0.5 1 1.5 2 2.5 3 3.5 4ωt

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

Incr

ease

in st

re

20%

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SPSWs tested by Tsai and Lee (2007) exceeded flexibility limit, yet performed comparably to SPSWs meeting limit

Flexibility Limit (cont’d)Flexibility Limit (cont’d)

SPSW S (ωt=3.01>2.5)SPSW N (ωt=2.53>2.5)

Column Design Issues (cont’d)Column Design Issues (cont’d)

Case Researcher Specimen

identificationNumber of

stories tω nV

(kN)

2000sapV

(kN)

u designV −

(kN) Shear Yielding

(i) single-story specimen 1 Lubell et al (2000) SPSW2 1 3.35 75 108 113 Yes 2 Berman and Bruneau (2005) F2 1 1.01 932 259 261 No

(ii) multi-story specimen-a 3 Driver et al (1998) b 4 1 73 766 1361 1458 Yes

Prevention of In-Plane Shear YieldingEvaluation of previous specimens

Driver et al, 1997, ωt=1.73 Park et al, 2007ωt=1.58

3 Driver et al (1998) - 4 1.73 766 1361 1458 Yes4 Park et al (2007) SC2T 3 1.24 999 676 1011 No 5 SC4T 3 1.44 999 984 1273 No 6 SC6T 3 1.58 999 1218 1469 Yes 7 WC4T 3 1.62 560 920 1210 Yes 8 WC6T 3 1.77 560 1151 1461 Yes 9 Qu and Bruneau (2007) -b 2 1.95 2881 1591 2341 No 10 Tsai and Lee (2007) SPSW N 2 2.53 968 776 955 No 11 SPSW S 2 3.01 752 675 705 No

a For multi-story specimens, VBEs at the first story are evaluated. b Not applicable.

Park et al, 2007, ωt=1.62

Lubell et al, 2000, ωt=3.35

Excessive flexibility exampleExcessive flexibility exampleTheoretically, with infinitely elastic beam/columns, could purposely assign high L/h ratio and low stiffness to the boundary elements (Bruneau and Bhagwadar 2002)Truss members 1 to 8 in compression as a result of beam and column deflections induced by the other strips in tension –entire tension field is taken by the last four truss members. yBehavior even worse if bottom beam free to bend.This extreme (not practical) example nonetheless illustrates how non-uniform yielding can occur

Tension FieldsTension Fields

2 0E+005

4.0E+005

6.0E+005

8.0E+005

1.0E+006

1.2E+006

Base

She

ar (N

)

Specimen: Two-story SPSW (SPSW S)Flexibility factor: ω =3 01

0.4

0.60.81.0

1.2

σ / f

y

1F Drift = 0.3%

0.0

0.20.4

0.60.81.0

1.2

σ / f

y

1F Drift = 0.2%

0.0

0.20.4

0.60.81.0

1.2

σ / f

y

1F Drift = 0.1%

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.51F Drift (%)

0.0E+000

5.0E+005

1.0E+006

1.5E+006

2.0E+006

2.5E+006

3.0E+006

3.5E+006

Bas

e Sh

ear (

N)

Specimen: Four-story SPSWFlexibility factor: ωt=1.73Researcher: Driver (1997)

0.0E+000

2.0E+005 Flexibility factor: ωt=3.01Researchers: Tsai and Lee (2007)

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0x/lα

0.00.2

0.40.60.8

1.01.2

σ / f

y

1F Drift = 2.0%

Lee and Tsai (2008)Driver (1997)

0.00.2

0.40.60.81.0

1.2

σ / f

y

1F Drift = 0.6%

0.0

0.2

o

x

lα

HBE HBE FBDFBD

Compressionstrut betweencolumns

(B)d

ωybi+1

fish plate web of intermediate beam flange of intermediate beam

ωybi

ωxbi

ωxbi+1

L

SPSWSPSWSPSW

columnsResultant forcesfrom yieldingof strips

o

+-

+ -V V VV

ωybi-ωybi+1

Vv(x)

o

-

(ωybi+ωybi+1)(d+2hf)/2

Vh(x)

HBE Moment DiagramHBE Moment Diagram

0.5

1.0

1.5

2.0

: M(x

) / ( ω

L2 /8)

κ=0.0κ=0.5κ=1.0κ=1.5κ=2.0Maximum

In-Span HBE Hinging

Optional Alternative: RBS at HBE ends

Design for wL2/4

-2.0

-1.5

-1.0

-0.5

0.0

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1Fraction of span from left support

Nor

mal

ized

Mom

ent: Hinging

8/12/2012

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Case Study: Design OutputsCase Study: Design Outputs

W16x36

W12x22

x50

x50

W16

x40

1)

(0.9

6)

10 ft tplate = 0.036 in S = 19.69 in Astrip = 0.72 in2

(0.88)

tplate = 0.059 in

(0.98)

W18x76

W14x61

x76

x76

W16

x89

9)

(0.9

8) tplate = 0.036 in

S = 19.69 in Astrip = 0.72 in2

(0.99)

tplate = 0.059 in

(0.99)

(0.9

8)

9)

(0.9

6)

1)

W16

x89

W16

x40

W12x19

W24x62 (0.91)

W24

x62

W18

x

W24

x62

W18

x(0

.99)

(0

.91

20 ft

10 ft

10 ft plate

S = 19.69 in Astrip = 1.17 in2

tplate = 0.072 in S = 19.69 in Astrip = 1.42 in2

(0.92) W12x45

W24x117 (0.98)

W24

x146

W

18x

W24

x146

W

18x

(0.9

6)

(0.9

9

20 ft

plateS = 19.69 in Astrip = 1.17 in2

tplate = 0.072 in S = 19.69 in Astrip = 1.42 in2

(0.95)

(0.9

9(0

.96)

(0.9

1(0

.99)

SPSW-ID SPSW-CD

Design HBEs for wL2/4

Monotonic PushoverMonotonic PushoverΔi+2

Δi+1

Vi+2

Vi+1

L2 L1

θθ +21 / LLθθ +21 / LL

ωb

Sway and Beam Combined Mechanism

∑∑==

⎟⎟⎠

⎞⎜⎜⎝

⎛

−=

ss n

ipbi

p

pn

iii M

LLL

HV011

2

∑∑==

+ −−+ss n

iiwiyp

n

iiwiwipyp HLtFHttLF

11

11 )2(sin

21)2(sin)(

21 αα

Plastic Hinge on the HBEs

Hi

Hi+1

Hi+2

Δi

Vi

θ

Lp

L2 L1 Strips remained

elastic

Plastic Hinge

b

ωc

α

∑=

+−++sn

ipwiwiypwyp

LLtLtF

LLtF

1

1212

1221 2

cos)(2

cos αα

Horizontal component of the strip yield forces

Vertical component of the strip yield forces

Case Study: Strength per this plastic mechanism is 13% less than per sway mechanism

Cyclic Pushover AnalysisCyclic Pushover Analysis

7.2

10.8

14.4

(in)

2%

3%

4%

• Monotonic: in-span plastic hinge + significant HBE vertical deformation

• Cyclic: to investigate whether phenomenon observed in monotonic analysis may lead to progressively increasing deformations

• Loading history:

-14.4

-10.8

-7.2

-3.6

0

3.6

1 2 3 4 5 6 Number of Cycles, N

Top

Floo

r Dis

plac

emen

t, Δ

-4%

-3%

-2%

-1%

0%

1%

Late

ral D

rift (

%)

Cyclic Pushover AnalysisCyclic Pushover Analysis

1 5

-1.0

-0.5

0.0

cem

ent (

in) .

-4% -3% -2% -1% 0% 1% 2% 3% 4%Lateral Drift

Significant accumulation of plastic incremental deformationon SPSW-ID

-3.0

-2.5

-2.0

-1.5

-14.4 -10.8 -7.2 -3.6 0 3.6 7.2 10.8 14.4Lateral Displacement (in)

Vert

ical

Dis

plac

SPSW-CDSPSW-ID

HBE3 Vertical Displacements

Time history analyses show same behavior, with vertical displacements increasing with severity of ground excitation level

Cyclic Pushover AnalysisCyclic Pushover Analysis

-1.0

-0.5

0.0

0.5

1.0

M/M

p

HBE2

SPSW-ID • Comparing rotation demands atbeam to column connection

• Curves bias toward one direction• Maximum Rotations:

SPSW-ID = 0.062 radiansSPSW-CD = 0.032 radians

HBE2

-2.5 -2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0

θ/ θ 0.03

-1.0

-0.5

0.0

0.5

1.0

M/M

p

SPSW-CD

Normalized Moment Rotation (θ/0.03)

• AISC 2005 Seismic Specifications:

Ordinary-type connections beused in SPSW

deserve more attentionin future research

Plastic Analysis ApproachPlastic Analysis Approach

Yielding stripsPlastic Hinges

For designstrength, neglectplastic hingescontribution

hM

LtFV py

⋅+⋅⋅⋅⋅=

42sin

21 α

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Plastic Analysis ApproachPlastic Analysis ApproachInterpretation #2: Lateral load Vu=

Interpretation #1:

hM

LtFV py

⋅+⋅⋅⋅⋅=

42sin

21 α

Interpretation #1: Lateral load Vu=

Single Story SPSW ExampleSingle Story SPSW ExampleDesign

α

h

L

Force assigned to infill panel

( )1 sin 22design yp wV f t Lhκ α⋅ =

Single Story SPSW ExampleSingle Story SPSW Example

1 25

1.50

1.75

2.00

2.25

desi

gn

L/h=0.8L/h=1.00L/h=1.5L/h=2L/h=2.5

Overstrength from capacity design

45α =

1.0β =

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1κ

0.00

0.25

0.50

0.75

1.00

1.25

V pla

stic

/ Vd

Balance point

Design force to be assigned to boundary moment frame

1

2

112 1 1

balanceLh

βκβ

−⎡ ⎤

= + ⋅⎢ ⎥⎢ ⎥+ −⎣ ⎦

Case StudyCase Study

30000

40000

50000ht

(lb)

0

10000

20000

AISC PROPOSED 75% 40%

Wei

gh

Panel HBE VBE Total

Quantifying Quantifying PerformancePerformance• Time history analyses of SPSWs

designed with various k value revealed different drift response

• Need to rigorously quantify • Need to rigorously quantify significance in terms of seismic performance

• FEMA P695 procedure is a useful tool for that purpose

Seismic Performance FactorsSeismic Performance FactorsParameter SW320 SW320K Reference

1. Design StageR 7 7 ATC63 Design 3-Story SPSW Big Size 100%.xlsVdesign 176 176 ATC63 Design 3-Story SPSW Big Size 49%.xls

2. Nonlinear Static (Pushover) AnalysisVVmax 495 226δy,eff 1.80 1.8 Pushover Curve for SW320 and SW320K.xlsδu 8.86 8.64Ω = Vmax/Vdesign 2.81 1.29 Included SH = 2%, Ωd = 1.2 and φ = 0.9μT = δu/δy,eff 4.92 4.80

3. Incremental Dynamic Analysis (IDA)SCT 3.60 2.29 IDA Curve for SW320 Sa PDGravity+Leaning.xlsSMT 1.50 1.50 IDA Curve for SW320K Sa PDGravity+Leaning.xlsCMR = SCT/SMT 2.40 1.53

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Typical Archetype ModelTypical Archetype ModelOPENSEES Model:

• Fiber Hinges on HBE andVBE ends

• Axial Hinges on Strips

• Gravity loads applied onSPSW according to its

Dual Strip Model P-Δ Leaning Column

SPSW according to itstributary area.

• Remaining loads applied on Leaning columns

Component Degradation ModelComponent Degradation Model

δ

P

EA

Py

δy

SH = 2%

Pcap

No Compression

Strength

9.0δy 10.7δy

0.015 0.018(Axial

θ

M

EI

My

-My

-θy θy

SH = 2%

0.039 0.064

Mcap

Symmetric

0.081

(a) Boundary Elements

(b) Strips

Strain)

Failure mode developed based on 33 previously tested SPSW specimens

Degradation model verified on 1 to 4 story SPSW specimens

Incremental Dynamic Analysis (IDA) Results Incremental Dynamic Analysis (IDA) Results -- SaSaSW0320

0.6

0.8

1

f Col

laps

e

SW0320K

0

0.2

0.4

0 5 10

Spectral Acceleration, ST (Tn = 0.36 Sec.), g

Pro

babi

lity

of

SW320Lognormal SW320SW320KLognormal SW320K

Seismic Performance FactorsSeismic Performance FactorsParameter SW320 SW320K Reference

1. Design StageR 7 7 ATC63 Design 3-Story SPSW Big Size 100%.xlsVdesign 176 176 ATC63 Design 3-Story SPSW Big Size 49%.xls

2. Nonlinear Static (Pushover) AnalysisVVmax 495 226δy,eff 1.80 1.8 Pushover Curve for SW320 and SW320K.xlsδu 8.86 8.64Ω = Vmax/Vdesign 2.81 1.29 Included SH = 2%, Ωd = 1.2 and φ = 0.9μT = δu/δy,eff 4.92 4.80

3. Incremental Dynamic Analysis (IDA)SCT 3.60 2.29 IDA Curve for SW320 Sa PDGravity+Leaning.xlsSMT 1.50 1.50 IDA Curve for SW320K Sa PDGravity+Leaning.xlsCMR = SCT/SMT 2.40 1.53

Seismic Performance Factors, Cont.Seismic Performance Factors, Cont.

4. Performance EvaluationT 0.36 0.36 FEMA P695 (ATC63) Eq. 5-5SDC Dmax Dmax FEMA P695 (ATC63) Table 5-1SSF (T, μT) 1.25 1.25 FEMA P695 (ATC63) Table 7-1bACMR = SSF (T, μT) x CMR 3.00 1.91βRTR 0.4 0.4 FEMA P695 (ATC63) Section 7.3.1βDR 0.2 0.2 FEMA P695 (ATC63) Table 3-1: (B - Good)

Parameter SW320 SW320K Reference

βTD 0.35 0.35 FEMA P695 (ATC63) Table 3-2: (C - Fair) βMDL 0.2 0.2 FEMA P695 (ATC63) Table 5-3: (B - Good)βtot = sqrt (βRTR

2 + βDR2 + βTD

2 + βMDL2) 0.60 0.60

ACMR20% (βtot) 1.66 1.66 FEMA P695 (ATC63) Table 7-3ACMR10% (βtot) 2.16 2.16 FEMA P695 (ATC63) Table 7-3Statusi Pass Pass FEMA P695 (ATC63) Eq. 7-6StatusPG Pass NOT Pass FEMA P695 (ATC63) Eq. 7-75. Final ResultsR 7 Try AgainΩ 2.8 Try AgainμT 4.9 Try AgainCd = R 7 Try Again

Fragility Curve: DM (InterFragility Curve: DM (Inter--story Drift) for SW320story Drift) for SW320

0.6

0.8

1

f Exc

eeda

nce

DM: 1% Drift

0

0.2

0.4

0 2 4 6 8 10

Spectral Acceleration, ST (Tn = 0.36 Sec.), g

Prob

abili

ty o

f DM: 2% DriftDM: 3% Drift

DM: 4% Drift

DM: 5% DriftDM: 6% Drift

DM: 7% DriftDM: Collapse Point

Design Level Sa = 1.5g

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10

Fragility Curve: DM (InterFragility Curve: DM (Inter--story Drift) for SW320Kstory Drift) for SW320K

0.6

0.8

1

f Exc

eeda

nce

DM: Drift 1%

DM: Drift 2%

0

0.2

0.4

0 2 4 6 8 10

Spectral Acceleration, ST (Tn = 0.36 Sec.), g

Prob

abili

ty o

f

DM: Drift 3%

DM: Drift 4%

DM: Drift 5%

DM: Drift 6%

DM: Drift 7%

DM: Collapse Point

Design Level Sa = 1.5g

Perforated Steel Plate Shear Perforated Steel Plate Shear Walls (PWalls (P--SPSW)SPSW)

(to reduce tonnage of steel (to reduce tonnage of steel (to reduce tonnage of steel (to reduce tonnage of steel in lowin low--rise SPSWs)rise SPSWs)

Infill Infill OverstrengthOverstrength

Available infill plate material might be thicker or stronger than required by design. Several solution to alleviate this concernSeveral solution to alleviate this concern

Light-gauge cold-rolled steel Low Yield Steel (LYS) steel Perforated Steel Plate Shear Wall

Perforated Wall ConceptPerforated Wall Concept

3

4

A B C D E F

1

2

Specimen P at 3.0% DriftSpecimen P at 3.0% Drift Perforated Layout, Cont.Perforated Layout, Cont.

Sdiag θ

“Typical” diagonal strip

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11

Typical Perforated Strip (Typical Perforated Strip (VianVian 2005)2005)

L = 2000 mm

Sdiag = 400 mm

2δ

D ABAQUS S4 “Quadrant” Model

D = variable

δ½ L

t = 5 mm

½ Sdiag Sdiag

not actual mesh

Typical Strip Analysis Results (ST1)Typical Strip Analysis Results (ST1)At monitored strain At monitored strain eemaxmax = 20%, D = 100 mm (D/= 20%, D = 100 mm (D/SSdiagdiag = 0.25)= 0.25)

(a) Strip Mesh and Deformed Shape (Deformation Scale Factor = 4)

(b) Maximum In-Plane Principal Stress Contours

(c) Maximum In-Plane Principal Strain Contours

FLTB Model: Typical Panel ResultsFLTB Model: Typical Panel ResultsAt monitored strain At monitored strain εεmaxmax = 20%, D = 200 mm (D/= 20%, D = 200 mm (D/SSdiagdiag = 0.471)= 0.471)

Maximum In-Plane Principal Strain Contours

FLTB ModelFLTB Model

2.5

3.0

3.5

4.0

4.5

5.0

rip E

long

atio

n, ε

un (%

)Strip emax = 20% Panel emax = 20%Strip emax = 15% Panel emax = 15%Strip emax = 10% Panel emax = 10%Strip emax = 5% Panel emax = 5%Strip emax = 1% Panel emax = 1%

0.0

0.5

1.0

1.5

2.0

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7

Perforation Ratio, D/Sdiag

Tota

l Uni

form

Str

Shear Strength vs. Frame DriftShear Strength vs. Frame Drift

1500

2000

2500

3000

tren

gth,

Vy (

kN)

emax = 20%emax = 15%emax = 10%

0

500

1000

1500

0.0 1.0 2.0 3.0 4.0 5.0Frame Drift, γ

Tota

l She

ar S

t

emax = 5%emax = 1%SolidD050 (D/Sdiag = 0.12)D100 (D/Sdiag = 0.24)D150 (D/Sdiag = 0.35)D200 (D/Sdiag = 0.47)D250 (D/Sdiag = 0.59)D300 (D/Sdiag = 0.71)Bare

Infill Shear Strength: RF Infill Shear Strength: RF ModelModel

0.6

0.7

0.8

0.9

1.0

Vyp

51.5%

0.0

0.1

0.2

0.3

0.4

0.5

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0D/Sdiag

Vyp.

perf

/

Predicted (Eq. 4.3)γ = 5%γ = 4%γ = 3%γ = 2%γ = 1%Linear Reg.

ypperfyp VSdiag

DV ⋅⎥⎦⎤

⎢⎣⎡ −= 1. α

α = 0.7correction factor:

8/12/2012

12

Implementation of PImplementation of P--SPSWSPSW

Courtesy of Robert Tremblay, Ecole Polytechnique, et Eric Lachapelle, Lainco Inc, Montreal

ReplaceabilityReplaceability of Web Plate of Web Plate in SPSWin SPSW

Experimental ProgramExperimental Program

Phase I: Pseudo-dynamic load to an earthquake having a 2% in 50 years probability of occurrence. (Chi Chi CTU082EW--2╱50 PGA=0 67g)(Chi_Chi_CTU082EW--2╱50 PGA=0.67g)Cut-out and replace webs at both levelsPhase II: Repeat of pseudo-dynamic load to an earthquake having a 2% in 50 years probability of occurrence. Subsequently cyclic load to failure.

Web replacementWeb replacement

Buckled web plate from first pseudo-dynamic test cut out dynamic test cut out and new web plate welded in place

PseudoPseudo--dynamic Test (cont’d)dynamic Test (cont’d) PseudoPseudo--dynamic Test (cont’d)dynamic Test (cont’d)

1st story 2nd story

Specimen after the maximum peak drifts of 2.6% at lower story and 2.3% at upper story in pseudo-dynamic test.

8/12/2012

13

Subsequently Cyclic Test Subsequently Cyclic Test Severe plate damage and intermediate beam damage also occurred at drifts between 2.5% and 5%

Subsequently Cyclic Test (cont’d)Subsequently Cyclic Test (cont’d)

1st Story after interstory drift of 5%

2nd story after interstory drift of 5%

SelfSelf--Centering Centering (Resilient) SPSWs(Resilient) SPSWs

(SC(SC--SPSWs)SPSWs)

Self-Centering SPSW Concept:Replace rigid HBE to VBE joint connections of a conventional SPSW with a rocking connection combined with Post-Tension elements.

Energy dissipation provided by yielding Energy dissipation provided by yielding of infill plate only (not shown in figure)HBE, VBE and P.T. components designed to remain essentially elasticElastic elongation of P.T. about a rocking point provides a self-centering mechanism

UB Test-Setup (Full Infill Plate Frames) UB Specimen (Rocking about Flanges)

8/12/2012

14

Accommodating Beam Growth with Large Columns

Courtesy of Greg MacRae, University of Canterbury, New Zealand

UB Test Frame:Additional Test Frame Configurations:

New Zealand-inspired – Buffalo Resilient Earthquake-resistant Auto-centering while Keeping Slab Sound (NewZ-BREAKSS) Rocking Connection

Test Frames w/ Infill Strips

Frame w/ NewZ-BREAKSS Conn.

NewZ-BREAKSS Rocking ConnectionRadius Cut-Out

Rocking Point (Ea. End of HBE)

P t T i

Continuity PlateW8x HBE

Light GageWeb Plate

W6x VBE

Post-Tension

VBE Web Dblr Plate

Flange Reinf. Plate

Comments:Schematic detail shown of UB 1/3 test frame connection currently being tested at UB Eliminates PT Frame expansion by HBE rocking at the beam top flanges only

Post-TensionEccentricity

Shear Plate w/Horiz. Long Slotted Holes

(Ea. Side of HBE Web)

Stiffener Plates (Typ.)

Cant HBE Web (Ea. End of HBE)

NewZ-BREAKSS Rocking Connection

NewZ-BREAKSS Rocking Connection NewZ-BREAKSS Rocking Connection

8/12/2012

15

UB NewZ-BREAKSS Test Frame UB NewZ-BREAKSS Test Frame

UB NewZ-BREAKSS Test Results

Comments:Displacement control at top

level actuator with a slaved Force control at level 1 & 2

Top Story Drift (%)

ps)

NewZ-BREAKSS HysteresisFull Infill Plates

-3.4 -2.7 -2.0 -1.4 -0.7 0.0 0.7 1.4 2.0 2.7 3.4

2030405060

-3.4 -2.7 -2.0 -1.4 -0.7 0.0 0.7 1.4 2.0 2.7 3.4

2030405060

0.167Δy0.33Δy0.67 Δy1.0Δy2Δy3Δ

4Δy2% drift2.5% drift3% drift

Force control at level 1 & 2.

Force control load pattern of 1, 0.658, 0.316 at level 3, 2, 1 actuators used based on approximate first mode shape.

Top Story Displacement (in)

Bas

e Sh

ear

(ki

-5 -4 -3 -2 -1 0 1 2 3 4 5-60-50-40-30-20-10

01020

-5 -4 -3 -2 -1 0 1 2 3 4 5-60-50-40-30-20-10

01020 3Δy

Top Story Drift (%)

(kip

s)

NewZ-BREAKSS HysteresisFull Infill Plates - SAP2000

-4.5 -3 -1.5 0 1.5 3 4.5

2040

6080

-4.5 -3 -1.5 0 1.5 3 4.5

2040

6080

1) Test Frame - 2x0.5" strds2) APT = 4x0.5" strds3) APT = 6x0.5" strds4) APT = 6x0.6" strds

Top Story Displacement (in)

Bas

e Sh

ear

(k

-8 -6 -4 -2 0 2 4 6 8-80-60-40-20

020

-8 -6 -4 -2 0 2 4 6 8-80-60-40-20

020

*Residual Drift1) 1.85%2) 1.0%3) 0.85%4) 0.58%*modify HBE/VBEsizes as required

Discrete Strips Alternative

8/12/2012

16

UB Test Results – NewZ-BREAKSSTop Story Drift (%)

(kip

s)

-6 -4.5 -3 -1.5 0 1.5 3 4.5 6

20

40

60-6 -4.5 -3 -1.5 0 1.5 3 4.5 6

20

40

60SAP2000: 10% Comp.

No separation of the infill strips occurred (also observed with the flange rocking case).

Top Story Displacement (in)

Bas

e Sh

ear

-10.5 -7.5 -4.5 -1.5 1.5 4.5 7.5 10.5-60

-40

-20

0

-10.5 -7.5 -4.5 -1.5 1.5 4.5 7.5 10.5-60

-40

-20

0

PT Yielding Occured At Approx. 4.5% Top Story Drift

Testing stopped to be able to reused VBEs for subsequent shake table testing.

TubularTubular--link Eccentrically link Eccentrically Braced Frames (TEBF) Braced Frames (TEBF)

a.k.a.a.k.a.EBF with BuiltEBF with Built--up Box Links up Box Links

Eccentrically Braced FrameEccentrically Braced Frame

TubularTubular--link EBFlink EBF

EBFs with wide-flange (WF) links require lateral bracing of the link to prevent lateral torsional bucklingLateral bracing is difficult to provide in

b

dtf

tw

Fyw

Fyf

b

dtf

tw

Fyw

Fyf

b

dtf

tw

Fyw

Fyf

Lateral bracing is difficult to provide in bridge piersDevelopment of a laterallystable EBF link is warrantedConsider rectangular cross-section – No LTB

ProofProof--ofof--Concept TestingConcept Testing

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17

Finite Element Modeling of Finite Element Modeling of ProofProof--ofof--Concept TestingConcept Testing

Hysteretic Results for Refined ABAQUS Model and Proof-of-Concept Experiment

Link Testing Link Testing –– ResultsResultsLarge Deformation Cycles of Specimen X1L1.6

Design SpaceDesign SpaceStiffened LinksUnstiffened Links

ρ = 1.6yfFE0.64

ftb

ywFE0.64

ρywFE1.67

wtd Some slenderness limits

accidentally missing from AISC 341-10

Implementation Implementation of TEBFof TEBF

Towers of temporary structure to support and provide seismic

i t t d k f resistance to deck of self-anchored suspension segment of East Span of San-Francisco-Oakland Bay Bridge during its construction

MultiMulti--Hazard Design ConceptHazard Design Concept

Why Multi-Hazard Engineering Makes Sense?

EarthquakesEarthquakes

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Storm Surge or TsunamiStorm Surge or Tsunami CollisionCollision

http://www.dot.state.mn.us/bridge/Manuals/LRFD/June2007Workshop/10%20Pier%20Protection.pdf

FireFire Blast

Suicide truck-bomb collapsed the Al-Sarafiya bridge and sent cars toppling into the Tigris River (AP, (Baghdad, Iraq, April 2007)

MultiMulti--hazard solutionhazard solution

A true multi-hazard engineering solution is a concept that simultaneously has the desirable characteristics to protect and satisfy the multiple (contradicting) constraints inherent to multiple hazardsNeeds holistic engineering design that address all hazards in integrated framework A single cost single concept solution (not a combination of multiple protection schemes) Pay-off: Reach/protect more cities/citizens

ConcreteConcrete--Filled Steel Tubes Filled Steel Tubes (CFST) (CFST)

for blast and seismic for blast and seismic performanceperformanceperformanceperformance

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19

CFST Piles

“The Loma Prieta and Northridge earthquakes in California and the Kobe, Japan quake, along with re-examination of large-diameter cylinder pile diameter cylinder-pile behavior in the Alaskan earthquake of 1964, have demonstrated the superior ductility of concrete-filled steel tubular piles.”(Ben C. Gerwick Jr., ASCE Civil Engineering Magazine, May 1995)

Bridge carrying Broadway Ave. over the railroad in City of Rensselaer, NYBuilt 1975. No major rehab, although joints and wearing surface were redone

CFST Column Specimen (1CFST Column Specimen (1stst Series)Series)

68.5” 69.5”

164”

6” 5” 4”

16.5

”

CAP-BEAM

C6 C5 C4

59”

164”

6 5 4

32”FOUNDATION

BEAM

Concrete (no rebars) Concrete-Filled Steel Tube

CFST Column Test ResultsCFST Column Test ResultsTest 5: Bent 1, C5 (1.3X, W, Z=0.75m)

Dmax= 76 mm

Gap= 3 mm

Damage Progress of CFST Column Damage Progress of CFST Column (Column Deformations)(Column Deformations)

1.2 deg(0.021 rad) 2.2 deg

(0.038 rad)4.9 deg

(0.085 rad) 18.7 deg(0.327 rad)

Fracture of Column

3.8 deg(0.067 rad)

5.0 deg(0.088 rad)

8.3 deg(0.144 rad)

10.5 deg(0.182 rad)

17.0 deg(0.297 rad)

21.9 deg(0.382 rad)

PlasticDeformation

(Test 6 : B2-C4)

CoveredConcrete

Fracture of Steel Tube

Buckling of Steel Tube

BlewAway

Explosion

PlasticDeformation

(Test 9 : B2-C6)

On-set ofColumn Fracture(Test 10 : B2-C5)

Post-fractureof Column

(Test7 : B2-C4)

SeismicallySeismicallyDesignedDesignedDuctile ColumnDuctile Column

Shear FailureSeismic Design Alone is not a Alone is not a Guarantee of Multi-Hazard PerformanceNeed Optimal Seismic/Blast Design

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20

Jacketed NonJacketed Non--Ductile ColumnDuctile Column(Seismic Retrofit)(Seismic Retrofit)

Again Shear FailureSame conclusions

Comparison of Blast ParametersComparison of Blast Parameters

ReactionFrame

W

0.55W0.10W

Test 4Test 5

CFST Tests

W

RC, SJ Tests

250

750

StandoffDistance(in X)321.3

1.61.10.60.8

Test 1

Test 2Test 3

Test 7

Test 9,10 Test 6

Test 1,3 Test 2,4

2.16 3.25

Comparison of Column DamageComparison of Column Damage

18

38

59

80

102

123

144

165

188

216

1

3

5

7

8

11

12

12

13

14

1

6

10

17

19

21

24

28

32

37

1

6

10

15

19

23

27

31

35

39

HorizontalDeformation

(mm)

1.2 deg(0.021 rad)

0.7 deg(0.012 rad)

242

263

285

309

328

347

367

379

All longitudinalbars fractured.

15

16

16

15

16

15

14

13

40

45

50

52

57

62

67

71

75

All longitudinalbars fractured.

44

49

52

56

61

65

71

74

Explosion

79

250

Test 1 RC1(x = 2.16 X)

Test 2 RC2(x = 3.25 X)

Test 3 SJ2(x = 2.16 X)

Test 4 SJ1(x = 3.25 X)

3.8 deg(0.067 rad)

Test 6 CFST C4(x = 1.6 X)

24(Max)

2.9 deg(0.051 rad)

Fracture of Column

Calibration Work

BlewAway

e)

Post-fractureof Column

(Test7 : B2-C4)Blast Simulation Results

Proposed Multi Hazard Concept

• Analysis of concrete filled double skin tubes (CFDST) showed they can offer similar performance as CFST

• CFDST concentrates materials where needed for higher strength-to-weight ratio

8/12/2012

21

Blast Test Results

S1 @ 3% Drift S1 @ 7.5% Drift S1 @ 10% Drift

S5 @ 3% Drift S5 @ 6% Drift S5 @ 7.5% Drift

Enhanced Steel Jacketed Column

8/12/2012

22

ERDC Test on ESJC

• Results

Structural Fuses (SF)Structural Fuses (SF)

AnalogyAnalogy

Sacrificial element to protect the rest of the system.

mass, m

frame f

structural fuse, d

Ground Motion, üg(t)

frame, fbraces, b

Benefits of Structural Fuse Concept:Benefits of Structural Fuse Concept:

Seismically induced damage is concentrated on the fusesFollowing a damaging earthquake only the fuses

αK1 = Kf

V

Vp

VTotal

earthquake only the fuses would need to be replacedOnce the structural fuses are removed, the elastic structure returns to its original position (self-recentering capability)

Δya Δyf u

KfKa

K1

Vyf

Vyd

Vy

Frame

Structural Fuses

Model withModel withNippon Steel BRBsNippon Steel BRBs

Eccentric GussetEccentric Gusset--PlatePlate

8/12/2012

23

Test 1 Test 1 (PGA = 1g)(PGA = 1g)

Test 1Test 1First Story BRBFirst Story BRB

0

10

20

30

40

al F

orce

(kip

s)

-40

-30

-20

-10

0-0.5 -0.4 -0.3 -0.2 -0.1 0 0.1 0.2 0.3 0.4 0.5

Axial Deformation (in)

1st S

tory

Axi

a

Test 1 (Nippon Steel BRB Frame)Test 1 (Nippon Steel BRB Frame)First Story Columns ShearFirst Story Columns Shear

25

50

75

100

ns S

hear

(kN

)

-100

-75

-50

-25

0-5 -4 -3 -2 -1 0 1 2 3 4 5

Inter-Story Drift (mm)

1st S

tory

Col

umn

ABC Bridge Pier with ABC Bridge Pier with Structural FusesStructural FusesSpecimen S2Specimen S2--11

New “Short Length” BRB New “Short Length” BRB Developed by Star Seismic Developed by Star Seismic

8/12/2012

24

Specimen with BRB FusesSpecimen with BRB Fuses Specimen with BRB FusesSpecimen with BRB Fuses

Rocking Frames (RF)Rocking Frames (RF)

Controlled Rocking/Energy Controlled Rocking/Energy Dissipation SystemDissipation SystemAbsence of base of leg connection creates a rocking bridge pier system partially isolating the structure

Retrofitted Tower

Installation of steel yielding devices (buckling-restrained braces) at the steel/concrete interface controls the rocking response while providing energy dissipation

Existing Rocking BridgesExisting Rocking BridgesSouth Rangitikei Rail Bridge Lions Gate Bridge North Approach

Static, Hysteretic Behavior of Controlled Static, Hysteretic Behavior of Controlled Rocking PierRocking Pier

Device Response

FPED=0FPED=w/2

8/12/2012

25

Velocity

Limit forces through vulnerable members using structural “fuses”

Acceleration⇒

Design ProcedureDesign Procedure

Design ConstraintsDesign Chart:

6

8

10h/d=4

(in2) uby

Control impact energy to foundation and impulsive loading on tower legs by limiting velocity

⇒

Displacement DuctilityLimit μL of specially detailed, ductile “fuses”

⇒

β<1⇒ Inherent re-centering (Optional)

0 100 200 300 4000

2

4

constraint1constraint2constraint3constraint4constraint5

Lub (in.)

Aub

(

Lub

A u

Synthetic EQ 150% of DesignFree Rocking

Synthetic EQ 150% of DesignTADAS Case ηL=1.0

Synthetic EQ 150% of Design – Free Rocking Synthetic EQ 175% of Design - Viscous Dampers

ConclusionsConclusionsRecent research has enhanced understanding of seismic behavior of SPSW

Enhanced FBD for capacity design of HBEs/VBEsRevisited purpose of flexibility factorSignificance of HBE in-span hinging Significance of HBE in span hinging Implication of “balanced design”Post-EQ replaceability and expected drift demands

P-SPSW: Cost-effective for low-rise SPSWsSC-SPSW: Promising resilient systemTEBF, CFST, CFDST, SF, Rocking strategies