NEESR-SG: Controlled Rocking of Steel-Framed Buildings with Replaceable Energy Dissipating Fuses Greg Deierlein, Paul Cordova, Eric Borchers, Xiang Ma, Alex Pena,

Sarah Billington, & Helmut Krawinkler, Stanford University

Jerome Hajjar, Kerry Hall, Matt Eatherton, University of Illinois

Mitsumasa Midorikawa, Hokkaido University

Toko Hitaka, Kyoto University

David Mar, Tipping & Mar Associates and Greg Luth, GPLA

Component 1 – Stiff braced frame, designed to remain essentially elastic - not tied down to the foundation.

Component 2 – Post-tensioning strands bring frame back down during rocking

Component 3 – Replaceable energy dissipating fuses take majority of damage

Bumper or Trough

Controlled Rocking SystemControlled Rocking System

• Corner of frame is allowed to uplift.

• Fuses absorb seismic energy

• Post-tensioning brings the structure back to center.

Result is a building where the structural damage is concentrated in replaceable fuses with little or no residual drift

Rocked ConfigurationRocked Configuration

Controlled-Rocking SystemControlled-Rocking System

Bas

e S

hea

r

Drift

a

b c

d

f

g

Combined System

Origin-a – frame strain + small distortions in fusea – frame lift off, elongation of PTb – fuse yield (+)c – load reversal (PT yields if continued)

d – zero force in fusee – fuse yield (-)f – frame contactf-g – frame relaxationg – strain energy left in frame and fuse, small residual displacement

Fuse System

Bas

e S

hea

r

Drift

a

b c

d

efg

Fuse Strength Eff. FuseStiffness

PT Strength

PT – Fuse Strength

Pretension/Brace SystemB

ase

Sh

ear

Drift

a,f b

cde

g PT Strength

Frame Stiffness

e

2x FuseStrength

Shear Fuse Testing - Stanford

Panel Size: 400 x 900 mm

Attributes of Fuse high initial stiffness

large strain capacity

energy dissipation

Candidate Fuse Designs ductile fiber cementitious

composites

steel panels with slits

low-yield steel

mixed sandwich panels

damping devices

Trial Steel Fuse Configurations

Rectangular Link Panel Butterfly Panel

B

L

b

thickness t

h a

KEY PARAMETERS:

• Slit configuration

• b/t and L/t ratios

• Butterfly – b/a ratio

• Out of plane bracing

Similar Deformation Mode

ABAQUS Modeling of Fuse

Prototype StructurePrototype Structure

A B C D E

1

2

3

4

4@30' = 120'-0"

7

5

6

2'-0"

3" METAL DECK W/ 2-1/2" CONCRETE FILL, 5-1/2" TOTAL THICKNESS

PENTHOUSE

6@

30

' =

1

80

'-0

"

W12X26

W12 X30

W12X26

W12 X30

W12

X12

0

W12

X17

0

W12

X17

0

W12

X12

0

W12 X30

W12X26

W12 X30

W12X26

W12

X10

6 W12X

96

W12X

53

W12

X87

W12

X96

W12X

53

W12X

106W12

X96

W12

X53

W12X

87

W12X

96

W12

X53

Weight Mass Mass Level (kips) (kips-sec2/ft) (metric ton) Roof 2282 70.9 1033 Other Floors 2110 65.5 956

1. A/B ratio – geometry of frame

2. Overturning Ratio (OT) – ratio of resisting moment to design overturning moment. OT=1.0 corresponds to R=8.0, OT=1.5 means R=5.3

3. Self-Centering Ratio (SC) – ratio of restoring moment to restoring resistance.

4. Initial P/T stress

5. Frame Stiffness

6. Fuse type including degradation

)( BAV

FA

M

MSC

P

PT

resist

restore

OVT

PPT

OVT

resist

M

BAVFA

M

MOT

)(

“A” “A”

FPT FPT

Vp/3

Vp/3

Vp/3

“B”

Parametric Study – Parameters Parametric Study – Parameters StudiedStudied

0

0.01

0.02

0.03

0.04

0.05

Roo

f D

rift

Rat

io D

eman

d (m

m/m

m)

1.5 2.0 2.3 2.5 3.0

A/B Ratio OT Ratio

0.75 1.0 1.25 1.5 2.0

SC Ratio

0.5 0.75 1.0 1.5 2.0

0%

2%

4%

6%

8%

10%

12%

14%

16%

18%

Pea

k F

use

She

arS

trai

n D

eman

d (m

m/m

m)

1.5 2.0 2.3 2.5 3.0

A/B Ratio OT Ratio

0.75 1.0 1.25 1.5 2.0

SC Ratio

0.5 0.75 1.0 1.5 2.0

0

1

2

3

4

5

6

7

8

50% / 50 Median

50% / 50 Median + Std. Dev.

10% / 50 Median

10% / 50 Median + Std. Dev.

2% / 50 Median

2% / 50 Median + Std. Dev.

1.5 2.3 2.5 3.0

OT Ratio

0.75 1.0 1.25 1.5 2.0

SC Ratio

0.5 0.75 1.0 1.5 2.0

OT=1.0

SC=1.0

A/B=2.3

SC=1.0

A/B=2.3

OT=1.0

Sample of Parametric Study Results: Sample of Parametric Study Results: Mean Values of Peaks from Time HistoriesMean Values of Peaks from Time Histories

UIUC Half Scale TestsUIUC Half Scale Tests

Post-Tensiong

Strands

Fuse

Stiff Braced Frame

Bumpers

Loading and Boundary Condition Box (LBCB)

Spe

cim

en

Strong Wall

UIUC Half Scale TestsUIUC Half Scale Tests

UIUC Half Scale Tests UIUC Half Scale Tests Typical Alternative Configuration: Six FusesTypical Alternative Configuration: Six Fuses

UIUC Half Scale TestsUIUC Half Scale Tests

STRONG FLOOR

BASE PLATE

W6X16 BUMPER

X 3'-8"

THREADED HOLES BY UIUC

POST-TENSIONINGSTRANDS

FOUR - 1/2" STIFFENERS

1/2" GUSSET PLATE NS & FS

ANCHORAGE PLATE

ANCHORAGE PLATE

1" GUSSET PLATENS & FS

1/2" RADIUS BULL NOSE 3 SIDES

5" RADIUS ON GUSSET

NO CONNECTION BETWEEN THESE

TWO PLATES

BUMPERS ON THREE SIDES UP AGAINST FRAME

Elevation of Post Tensioning Column Base

Test MatrixTest Matrix

Test ID

Dim “B” 1

A/B Ratio

OT Ratio

SC Ratio

Num. of 0.5” P/T Strands

Initial P/T Stress2

and Force

Fuse Type and Fuse Strength

Fuse Configuration Testing Protocol

A1 2.06’ 2.5 1.0(R=8)

0.8 8 0.287 Fu(94.8 kips)

Steel Butterfly 1(84.7 kips)

Six – 1/4” thick fuses3F-025-AB2.5-OT1.0

Quasi-Static

A2 2.06’ 2.5 1.0(R=8)

0.8 8 0.287 Fu(94.8 kips)

Steel Butterfly 2(84.7 kips)

Two – 5/8” thick Fuses1F-0625-AB2.5-OT1.0

Quasi-Static

A3 2.06’ 2.5 1.5(R=8)

0.8 8 0.430 Fu(142.3 kips)

Steel Butterfly 3(84.7 kips)

Two – 5/8” thick Fuses1F-0625-AB2.5-OT1.5

Hybrid Simu-lation3

A4 2.06’ 2.5 1.5(R= 5.3)

0.8 8 0.430 Fu(142.3 kips)

Steel Butterfly 3

(127.0 kips)

Two – 1” thick Fuses1F-1-AB2.5-OT1.5

Quasi-Static

B1 3.06’ 1.69 1.0(R=8)

0.8 7 0.328 Fu(94.8 kips)

Steel Butterfly 4(75.4 kips)

Six – 1/4” thick fuses3F-025-AB1.69-OT1.0

Quasi-Static

B2 3.06’ 1.69 1.0(R=8)

0.8 7 0.328 Fu(94.8 kips)

Steel Butterfly 5 (75.4 kips)

Two – 5/8” thick Fuses1F-0625-AB1.69-

OT1.0

Quasi-Static

B3 3.06’ 1.69 1.0(R=8)

0.8 7 0.328 Fu(94.8 kips)

Steel Butterfly

4a(75.4 kips)

Six – 1/4” thick fuses3F-025-AB1.69-OT1.0

Hybrid Simu-lation3

B4 3.06’ 1.69 1.5(R= 5.3)

0.8 7 0.492 Fu(142.3 kips)

Steel Butterfly 6

(113.2 kips)

Two – 1” thick Fuses1F-1-AB1.69-OT1.5

Quasi-Static

System Test at E-Defense (2009)System Test at E-Defense (2009)

Large (2/3 scale) frame assembly

Validation of dynamic response and simulation

Proof-of-Concept

construction details

re-centering behavior

fuse replacement

Collaboration & Payload ProjectsSpecial thanks to Profs. Takeuchi, Kasai, Nakashima and all those involved

in the testbed development and E-Defense operations

1. Seismic loads prescribed in current building codes assume considerable inelasticity in the structure during a severe earthquake. This can result in structural damage and residual drift that cannot be economically repaired.

2. The controlled rocking system satisfies two key performance goals:a) Minimize residual drift.b) Concentrate bulk of structural damage in replaceable fuses.

3. Experimental and analytical work has been carried out at Stanford to optimize fuses.

4. A parametric study was conducted at UIUC to optimize A/B ratio, OT ratio, and SC ratio.

5. Half-scale tests will be conducted at the UIUC MUST-SIM Facility to improve details and validate the performance of the controlled rocking system for implementation in practice.

6. Tests will be carried out at E-Defense to further validate the system performance and demonstrate the self-centering and repairability of the controlled rocking system when subjected to a realistic ground motion.

ConclusionConclusion

Controlled Rocking ProjectControlled Rocking Project