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

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

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

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

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

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

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

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

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

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

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

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