1. Controlled Rocking of Steel Braced Frames
April 12-13, 2006
NEESR-SG: Controlled Rocking of Steel-Framed Buildings with Replaceable Energy Dissipating Fuses
Greg Deierlein, Sarah Billington,
& Helmut Krawinkler
Stanford University
Jerome Hajjar Mitsumasa Midorikawa
Univ. of Illinois Hokkaido University
US-Japan Meeting

2. Schematic Building Systems
Controlled Rocking of Steel Braced Frames
April 12-13, 2006
Schematic Building Systems
Structural Fuse
Post-tensioning (PT) Tendons
NOTE – we will likely use alternative configuration with chevron bracing and PT running down the center of the braced frames. A B A
US-Japan Meeting

3. Controlled Rocking of Steel Braced Frames
April 12-13, 2006
Controlled Rocking Brace Frames
Yielding of Structural Fuse
Structural Fuse
Post-tensioning (PT) Tendons
PT Cables & Braces remain elastic
Steel Braced Frame A B A
Could potentially employ additional fuse at base of column
US-Japan Meeting

4. Structural Fuse Options
Controlled Rocking of Steel Braced Frames
April 12-13, 2006
Structural Fuse Options
US-Japan Meeting

5. Controlled Rocking of Steel Braced Frames
April 12-13, 2006
HPFRCC Panels
Butterfly Panels
Height to width ratio of links close to 1 – likely a combination of shear and flexure behavior.
Could adjust A/B ratio to enforce more flexural yielding. A B
Slit Tapered Panels
Height to width ratio of links approximately 2-1.
Region detailed to carry shear after flexural hinging
Offset helps distribute stresses near connection, hopefully postponing splitting.
US-Japan Meeting

6. Steel Shear Wall with Slits
Controlled Rocking of Steel Braced Frames
April 12-13, 2006
Steel Shear Wall with Slits
Bolted connection to steel columns A B A
US-Japan Meeting

7. Reduced Web Section Beams
Controlled Rocking of Steel Braced Frames
April 12-13, 2006
Reduced Web Section Beams A B
Welded to steel plate
Bolted to steel column
US-Japan Meeting

8. Controlled Rocking of Steel Braced Frames
April 12-13, 2006
Viscous Dampers
Structural Fuse
Post-tensioning (PT) Tendons
PT Cables & Braces remain elastic A B A
US-Japan Meeting

9. Bilinear vs. Pinching Fuse
Controlled Rocking of Steel Braced Frames
April 12-13, 2006
Bilinear vs. Pinching Fuse
Not
Restoring
Restoring
PT Strength = Fuse Strength
(2PT*A) / (Vp,fuse (A+B)) = 1.0
The hysteretic behavior of the fuse can impact the way we design the PT to fuse strength ratio. A fuse with pinched behavior requires less restoring force to return back to zero displacement, therefore this allows us to provide a stronger fuse than if elastic perfectly plastic behavior is assumed.
US-Japan Meeting

10. Shake Table Test – PRELIMINARY (OLD) CONCEPT
Controlled Rocking of Steel Braced Frames
April 12-13, 2006
Shake Table Test – PRELIMINARY (OLD) CONCEPT
Large scale validation of full system (incl. floor slabs, restoring frame, connection details, etc.)
Proof of concept – construction and seismic performance
Validation of simulation tools (e.g., OpenSees)
US-Japan Meeting

11. Shake Table Test – LATEST CONCEPT
Controlled Rocking of Steel Braced Frames
April 12-13, 2006
Shake Table Test – LATEST CONCEPT
Note – it is unlikely we will use a slab. Instead, we will likely use some type of steel beam to provide lateral bracing.
US-Japan Meeting

12. Shake Table Test – LATEST CONCEPT
Controlled Rocking of Steel Braced Frames
April 12-13, 2006
Shake Table Test – LATEST CONCEPT
Discussion Points:
Interest in running multiple tests to look at alternative shear fuses, varying post-tensioning force, and perhaps other design variants. We need to think about the implications this has on rapid access to the specimen to make adjustments and replace fuses (perhaps while the table is energized).
The lateral bracing and connection to the testbed structure will need to allow for vertical rocking motion of frame and the attached beams.
We are thinking to test a 4-story structure since we need sufficient height to accommodate the induced deformations in the post-tensioning tendons.
We are interested to see if other Japanese researchers will be interested in collaborating on the rocking tests. Possible collaboration would include: (a) design/testing of alternative fuse types, (b) re-use of our specimen for alternative configurations, (c) other …
We would like to explore possibilities to leverage resources with other projects or sponsors to help defray costs of detailing, fabrication, and construction of specimen.
US-Japan Meeting