1. 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 1

2. Controlled Rocking System
Component 3 – Replaceable energy dissipating fuses take majority of damage
Component 2 – Post-tensioning strands bring frame back down during rocking
Component 1 – Stiff braced frame, designed to remain essentially elastic - not tied down to the foundation.
Bumper or Trough

3. Rocked Configuration 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

4. Controlled-Rocking System

5. Pretension/Brace System Fuse System
Base Shear
Drift
a,f b c d e g
PT Strength
Frame Stiffness
Fuse System
Base Shear
Drift a b c d e f g
Fuse Strength
Eff. Fuse
Stiffness b c
Origin-a – frame strain + small distortions in fuse
a – frame lift off, elongation of PT
b – fuse yield (+)
c – load reversal (PT yields if continued)
d – zero force in fuse
e – fuse yield (-)
f – frame contact
f-g – frame relaxation
g – strain energy left in frame and fuse, small residual displacement
Base Shear
2x Fuse
Strength d a PT
Strength e f
PT – Fuse Strength g
Drift
Combined System

6. Shear Fuse Testing - Stanford
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
Panel Size: 400 x 900 mm

7. Trial Steel Fuse Configurations
thickness t h a L b B
Rectangular Link Panel
Butterfly Panel
KEY PARAMETERS:
Slit configuration
b/t and L/t ratios
Butterfly – b/a ratio
Out of plane bracing

9. ABAQUS Modeling of Fuse
Similar Deformation Mode 9

10. Prototype Structure

11. Parametric Study – Parameters Studied
A/B ratio – geometry of frame
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
Self-Centering Ratio (SC) – ratio of restoring moment to restoring resistance.
Initial P/T stress
Frame Stiffness
Fuse type including degradation

12. Sample of Parametric Study Results: Mean Values of Peaks from Time Histories
OT=1.0
SC=1.0
A/B=2.3
SC=1.0
A/B=2.3
OT=1.0

13. UIUC Half Scale Tests

14. UIUC Half Scale Tests

15. UIUC Half Scale Tests Typical Alternative Configuration: Six Fuses

16. Elevation of Post Tensioning
UIUC Half Scale Tests
Elevation of Post Tensioning
Column Base

17. Test 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 fuses
3F-025-AB2.5-OT1.0
Quasi-Static A2
Steel Butterfly 2
Two – 5/8” thick Fuses
1F-0625-AB2.5-OT1.0 A3
1.5
0.430 Fu
(142.3 kips)
Steel Butterfly 3
1F-0625-AB2.5-OT1.5
Hybrid Simu-lation3 A4
(R= 5.3)
(127.0 kips)
Two – 1” thick Fuses
1F-1-AB2.5-OT1.5 B1
3.06’
1.69 7
0.328 Fu
Steel Butterfly 4
(75.4 kips)
3F-025-AB1.69-OT1.0 B2
Steel Butterfly 5 (75.4 kips)
1F-0625-AB1.69-OT1.0 B3
Steel Butterfly 4a B4
0.492 Fu
Steel Butterfly 6
(113.2 kips)
1F-1-AB1.69-OT1.5

18. 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
Special thanks to Profs. Takeuchi, Kasai, Nakashima and all those involved in the testbed development and E-Defense operations 18

19. Conclusion
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.
The controlled rocking system satisfies two key performance goals:
Minimize residual drift.
Concentrate bulk of structural damage in replaceable fuses.
Experimental and analytical work has been carried out at Stanford to optimize fuses.
A parametric study was conducted at UIUC to optimize A/B ratio, OT ratio, and SC ratio.
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.
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.

20. Controlled Rocking Project