3rd Annual EHKS Retreat 3rd Annual EHKS Retreat March 10, 2007 March 10, 2007 Allerton Park Allerton Park Controlled Rocking Steel Controlled Rocking Steel Frames with Replaceable Frames with Replaceable Energy-Dissipating Fuses Energy-Dissipating Fuses Matt Eatherton, MS SE University of Illinois at Urbana- Champaign
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3rd Annual EHKS Retreat March 10, 2007 Allerton Park
Controlled Rocking Steel Frames with Replaceable Energy-Dissipating Fuses. Matt Eatherton, MS SE University of Illinois at Urbana-Champaign. 3rd Annual EHKS Retreat March 10, 2007 Allerton Park. My Background. Born in Kansas City, 1975 BS in CE - University of Missouri at Columbia, 1997 - PowerPoint PPT Presentation
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• Born in Kansas City, 1975Born in Kansas City, 1975• BS in CE - University of Missouri at Columbia, 1997BS in CE - University of Missouri at Columbia, 1997• MS in CE - University of Missouri at Columbia, 1999MS in CE - University of Missouri at Columbia, 1999
– Master’s research involved instrumenting and monitoring four Master’s research involved instrumenting and monitoring four prestressed bridge girders with over 150 gages during construction and prestressed bridge girders with over 150 gages during construction and for one year in service.for one year in service.
• 2 years structural design experience in Kansas City2 years structural design experience in Kansas City• 5 years structural design experience in San Francisco5 years structural design experience in San Francisco• Volunteer Structural Engineering ActivitiesVolunteer Structural Engineering Activities
– Build Change – improving seismic resistance of housing in developing Build Change – improving seismic resistance of housing in developing countriescountries
examples, and other involvementexamples, and other involvement
• Began PhD program at UIUC in fall 2006 with the goal of getting an Began PhD program at UIUC in fall 2006 with the goal of getting an academic position afterwardacademic position afterward
Fuse Type Fuse Type and Fuse and Fuse StrengthStrength
Time Time Req’dReq’d
Testing Testing ProtocolProtocol
Reason for TestReason for Test
A1A1 3.09’3.09’ 1.751.75 1.01.0(R=8)(R=8)
0.314 Fu0.314 Fu(103.9 (103.9 kips)kips)
Steel Slit 1Steel Slit 1(82.6 kips)(82.6 kips)
4 4 weeksweeks
Quasi-Quasi-StaticStatic33
This configuration should produce the least amount of demands on This configuration should produce the least amount of demands on the fuses. If there are problems with the fuses, we may be able to the fuses. If there are problems with the fuses, we may be able to reconfigure.reconfigure.
A2A2 3.09’3.09’ 1.751.75 1.01.0(R=8)(R=8)
0.314 Fu0.314 Fu(103.9 (103.9 kips)kips)
ECC 1 ECC 1 (82.6 kips)(82.6 kips)
1 1 weekweek
Quasi-Quasi-StaticStatic33
If the system works in the first test, try an ECC fuse in this best-If the system works in the first test, try an ECC fuse in this best-case configuration.case configuration.
A3A3 3.09’3.09’ 1.751.75 1.01.0(R=8)(R=8)
0.314 Fu0.314 Fu(103.9 (103.9 kips)kips)
Steel Slit 3Steel Slit 3(82.6 kips)(82.6 kips)
2 2 weekweek
Hybrid Hybrid Simu-Simu-lationlation44
Now that we know how well this configuration responds, conduct a Now that we know how well this configuration responds, conduct a hybrid simulation to find out how the system will perform in a real hybrid simulation to find out how the system will perform in a real building. One of the main objectives is to examine effect of out-of-building. One of the main objectives is to examine effect of out-of-plane rotation.plane rotation.
A4A4 3.09’3.09’ 1.751.75 1.51.5(R=5.3)(R=5.3)
0.471 Fu0.471 Fu(155.8 (155.8 kips)kips)
Steel Slit 2Steel Slit 2(123.9 kips)(123.9 kips)
1 1 weekweek
Quasi-Quasi-StaticStatic44
Increase the OT to 1.5. The higher OT would result in lower Increase the OT to 1.5. The higher OT would result in lower ductility demands, so if it works, this would be the configuration ductility demands, so if it works, this would be the configuration proposed for better performance in a PBD. This configuration will proposed for better performance in a PBD. This configuration will also cause P/T yielding before the fuses are completely destroyed.also cause P/T yielding before the fuses are completely destroyed.
B1B1 2.16’2.16’ 2.52.5 1.51.5(R=5.3)(R=5.3)
0.471 Fu0.471 Fu(155.8 (155.8 kips)kips)
Steel Slit 4Steel Slit 4(139.1 kips)(139.1 kips)
4 4 weeksweeks
Quasi-Quasi-StaticStatic33
Now that we have an idea how well the system works, push the A/B Now that we have an idea how well the system works, push the A/B to 2.5, but with an OT of 1.5. This configuration still produced to 2.5, but with an OT of 1.5. This configuration still produced reasonable fuse shear strain demands in the parametric study.reasonable fuse shear strain demands in the parametric study.
B2B2 2.16’2.16’ 2.52.5 1.01.0(R=8)(R=8)
0.314 Fu0.314 Fu(103.9 (103.9 kips)kips)
Steel Slit 5Steel Slit 5(92.7 kips)(92.7 kips)
1 1 weekweek
Quasi-Quasi-StaticStatic33
Drop the OT back to 1.0. This configuration pushes the envelope Drop the OT back to 1.0. This configuration pushes the envelope with regards to fuse shear strain demand predicted by the with regards to fuse shear strain demand predicted by the parametric study.parametric study.
B3B3 2.16’2.16’ 2.52.5 1.01.0(R=8)(R=8)
0.314 Fu0.314 Fu(103.9 (103.9 kips)kips)
ECC 2ECC 2(92.7 kips)(92.7 kips)
1 1 weeksweeks
Quasi-Quasi-StaticStatic33
If the previous test with A/B = 2.5 and OT = 1.0 works, try an ECC If the previous test with A/B = 2.5 and OT = 1.0 works, try an ECC fuse. fuse. *We will cast another set of ECC fuses based on OT=1.5 and A/B = *We will cast another set of ECC fuses based on OT=1.5 and A/B = 2.5, in case system isn’t performing as well as expected. 2.5, in case system isn’t performing as well as expected.
B4B4 2.16’2.16’ 2.52.5 1.01.0(R=8)(R=8)
0.314 Fu0.314 Fu(103.9 (103.9 kips)kips)
Steel Slit 6Steel Slit 6(92.7 kips)(92.7 kips)
2 2 weekweek
Hybrid Hybrid Simu-Simu-lationlation44
For the finale, try a hybrid simulation at A/B = 2.5. Along with For the finale, try a hybrid simulation at A/B = 2.5. Along with other hybrid simulation, this will tell us how well the system might other hybrid simulation, this will tell us how well the system might perform in a real building.perform in a real building.
U - out-of-planeU - out-of-plane FreeFree Constrain to Constrain to be 0be 0
FreeFree Constrain to Constrain to be 0be 0
θ - in-planeθ - in-plane As necessary to As necessary to simulate applying simulate applying
gravity load to gravity load to exterior columnsexterior columns
FreeFree As necessary to As necessary to simulate applying simulate applying
gravity load to gravity load to exterior columnsexterior columns
FreeFree
θ - out-of-planeθ - out-of-plane FreeFree Constrain to Constrain to be 0be 0
FreeFree Constrain to Constrain to be 0be 0
θ - torsionθ - torsion FreeFree Constrain to Constrain to be 0be 0
FreeFree Constrain to Constrain to be 0be 0
The horizontal movement of the Left LBCB would be used to control the test. The Right LBCB will match the horizontal force in the left LBCB. This will apply the same amount of load to both frames, but allow differential rocking between the frames.
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. To provide a building that is relatively easy to repair after an earthquake, two attractive performance criteria are:a) Eliminate residual drift.b) Concentrate bulk of structural damage in replaceable fuses.
3. The controlled rocking system satisfies these performance goals.
4. The controlled rocking system consists of three major components:a) Stiff steel braced frame designed to remain essentially elastic, but
not tied down to the foundation.b) Post-tensioning that provides self-centering capability.c) Highly ductile energy dissipating fuses.
5. A multi-institution, international research project is underway to examine, improve, and validate the performance of this innovative system.
6. A parametric study was conducted to optimize A/B ratio, OT ratio, and SC ratio.
7. Some considerations in the design of the controlled rocking system include:a) Proportioning fuses and P/T to resist overturning, but still self-
center.b) Insuring enough P/T strain capacity.c) Using fuses with enough shear strain capacity based on frame
geometry (fuse shear strain is amplified compared to roof drift ratio).d) Preclude global overturning.
8. Half-scale tests will be conducted later this year at the UIUC MUST-SIM Facility to improve details and validate the performance of the controlled rocking system for implementation in practice.
9. Hybrid simulation tests will further validate the system performance and demonstrate the self-centering and repairability of the controlled rocking system when subjected to a realistic ground motion.