NEESR-SG: Controlled Rocking of Steel-Framed Buildings with Replaceable Energy Dissipating Fuses

International Association for Bridge and Structural Engineering

Creating and Renewing Urban Structures

NEESR-SG: Controlled Rocking of Steel-Framed Buildings with Replaceable Energy Dissipating Fuses

Gregory G. Deierlein, Sarah Billington, Helmut Krawinkler, Xiang Ma Stanford University

Jerome F. Hajjar, Matthew Eatherton University of Illinois at Urbana-Champaign

Mitsumasa Midorikawa, Hokkaido University

Toru Takeuchi, Tokyo Institute of Technology

T. Hikino, Hyogo Earthquake Engineering Research CenterDavid Mar, Tipping & Mar Associates and Greg Luth, GPLA

In-Kind Funding: Tefft Bridge and Iron of Tefft, IN, MC Detailers of Merrillville, IN, Munster Steel Co. Inc. of Munster, IN, Infra-Metals of Marseilles, IN, and Textron/Flexalloy Inc. Fastener Systems

Division of Indianapolis, IN.



Throw-away technology:Structure and Architecture absorbs energy through damage

Large Inter-story Drifts:Result in architectural & structural damage

High Accelerations:Result in content damage& loss of function

Deformed Section – Eccentric Braced Frame

Key Short Comings of Modern Seismic Design



New System

Develop a new structural building system that employs self-

centering rocking action and replaceable* fuses to provide

safe and cost effective earthquake resistance. *Key Concept – design for repair

Post-tensioning

Shear Fuse



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 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



Rocking Braced Frame w/Post Tensioning



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

Phase I: Shear Fuse Testing



Fuse Configurations

B

L

b

thickness t

h

a

Rectangular link: b/t and L/t Butterfly link: b/a

Welded end Buckling-restrained



Testing Results: Butterfly Links

B36-10 B56-09

B37-06 B14-02



B36-10 B56-09

B37-06 B14-02

Butterfly Links: Load-Deformation



Phase II: Half-Scale System Tests

In the Rig

General Specimen Design



Reaction Wall

Loading and Boundary Condition Box (LBCB)

Bumpers Restrain Horizontal Movement

(Not Shown Here)

Load Cell Pins Provide Load Data and

Feedback for Control

Anchorage Plate for the Post-Tensioning

Loading Beam Applies Loads to the Two

Frames

Test Setup at MUST-SIM FacilityNetwork for Earthquake Engineering Simulation (NEES)



Test MatrixTest ID

Dim “B”

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 0.85(R=9.4)

1.1 8 0.287 Fu(94.8 kips)

Steel Butterfly 3

(62.0 kips)


Quasi-Static

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)


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)


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)


Hybrid Simu-lation

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



Tested Configurations



Test Results – Hysteretic Behavior

-4 -3 -2 -1 0 1 2 3 4-150

-100

-50

0

50

100

150

Roof Drift Ratio (%)

App

lied

For

ce (

kips

)

Preliminary Analytical Model

Experimental Response

-4 -3 -2 -1 0 1 2 3 4-150

-100

-50

0

50

100

150


App

lied

For

ce (

kips

)

Preliminary Analytical Model

Experimental Response

Test A1 Test A2



-4 -3 -2 -1 0 1 2 3 4-150

-100

-50

0

50

100

150


App

lied

For

ce (

kips

)

Complete Response

Load Step 9

Load Step 12

-3 -2 -1 0 1 2 3 4-150

-100

-50

0

50

100

150


App

lied

For

ce (

kips

)

Complete Response

Load Step 9

Load Step 12

Test Results – Fuse Link Buckling



Test Results – Post Tensioning Force

-4 -3 -2 -1 0 1 2 3 450

100

150

200

250

300


Pos

t-T

ensi

on F

orce

(ki

ps)

Left Frame

Right Frame

Predicted for Left Frame

Predicted for Right Frame

-3 -2 -1 0 1 2 3 450

100

150

200

250

300


Pos

t-T

ensi

on F

orce

(ki

ps)

Left Frame

Right Frame

Predicted for Left Frame

Predicted for Right Frame

Test A1 Test A2



Test Results – Left Frame Column Uplift

-4 -3 -2 -1 0 1 2 3 4-0.5

0

0.5

1

1.5

2

2.5


Col

umn

Upl

ift (

in)

Left Column of Left Frame

Right Column of Left Frame

Prediction for Left Column of Left Frame

Prediction for Right Column of Left Frame

-3 -2 -1 0 1 2 3 4-0.5

0

0.5

1

1.5

2

2.5


Col

umn

Upl

ift (

in)

Left Column of Left Frame

Right Column of Left Frame

Prediction for Left Column of Left Frame

Prediction for Right Column of Left Frame

Test A1 Test A2



Test Results – Fuse Shear Strain

0 2000 4000 6000 8000 10000-15

-10

-5

0

5

10

15

Substep Number

Fus

e S

hear

Str

ain

(%)

Measured Fuse Shear Strain

Target Fuse Shear Strain

0 2000 4000 6000 8000 10000-15

-10

-5

0

5

10

15

Substep Number

Fus

e S

hear

Str

ain

(%)

Measured Fuse Shear Strain

Target Fuse Shear Strain

Test A1 Test A2



Test Frame Test-bed Unit



Controlled Rocking 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 Projects



Conclusions •The controlled rocking system exhibits excellent self-centering and

energy dissipating response. All indicators show that the system is constructable and viable for practice.

•The controlled rocking system will reduce life cycle costs by reducing structural repair costs after an earthquake.

•Butterfly steel plate shear fuses, tested at Stanford University, were able to sustain cyclic deformations as large as 25% shear strain or more and still absorb seismic energy.

•Half scale tests at University of Illinois are in progress. Tests A1, A2, and A3 are complete. More tests to come.

•Two-thirds scale shake table tests on a planar frame at E-Defense next summer will further validate system performance.

•Design recommendations will be develoeped to allow implementation in practice.



Video of Specimen A1Six ¼” fuses buckled late in the loading history; Peak drift: 3%; Peak shear strain:

11%

Documents

NEESR-SG: Controlled Rocking of Steel-Framed Buildings with Replaceable Energy Dissipating Fuses