1 / 44

Steel Confined Yielding Damper For Earthquake Resistant Design

Outline. Buckling-Restrained Brace backgroundUnbonded BraceConfined Yielding Damper (CYD) specimens and testing programResults of full-scale CYD testsConclusions. Buckling-Restrained Braced Frame (BRBF). Lateral force resisting systemLimit inelastic behavior and damage to frame members by inco

aulii
Download Presentation

Steel Confined Yielding Damper For Earthquake Resistant Design

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

    2. Outline Buckling-Restrained Brace background Unbonded Brace™ Confined Yielding Damper (CYD) specimens and testing program Results of full-scale CYD tests Conclusions

    3. Buckling-Restrained Braced Frame (BRBF) Lateral force resisting system Limit inelastic behavior and damage to frame members by incorporating separate energy dissipating (yielding) elements Added hysteretic damping Ability to specify brace yield force and stiffness to limit inter-story drift Reasonably stable and symmetric tension and compression behavior Greater design flexibility over tension only braces

    4. Global Buckling of Confining Tube Provide global buckling resistance of brace with outside structural tubing Euler Buckling Load: Where: E = Modulus of elasticity I = Moment of inertia of confining tube L = Brace Length (work point to work point) P = Maximum compressive load a = Factor of safety

    5. Unbonded Brace™ Developed by Nippon Steel Successful large-scale laboratory tests Numerous Japanese applications Approximately one dozen U.S. Unbonded Brace projects including Hewlett Packard in Corvallis, OR High performance

    6. Typical Braced Bay

    7. Confined Yielding Damper (CYD) Mortar of Unbonded Brace replaced with noncohesive media with no debonding layer required Economical, low yield force device for low rise structures Applicable to new buildings as well as retrofit of nonductile structures Makes use of standard materials Opens market to U.S. fabrication Allows post event inspection, and repair/replacement of yielding core while reusing major CYD components Simplified brace to frame connections

    8. Specimens

    9. Specimen Properties

    10. Specimen Fabrication Tube filled in vertical orientation Compacted with dead blow hammer on outside of tube / pencil vibrator inside tube to achieve approximate 95% relative density of confining media End caps and threaded rod used to maintain confining media volume within steel pipe

    11. Test Matrix

    12. 556 kN (125 kip) Dog Bone Confining Media

    13. 556 kN (125 kip) Perforation Blocking Configuration

    14. Testing

    15. Cyclic Displacement History

    34. Evaluation Parameters C/T – maximum compression force divided by maximum tension force (AISC/SEAOC maximum of 1.3) Energy dissipated – area under force-displacement curve Cumulative ductility – total inelastic deformation (AISC/SEAOC minimum of 140 Dby)

    35. 556 kN (125 kip) Dog Bone – Good Performance (125DB-2)

    36. 556 kN (125 kip) Dog Bone – Good Performance (125DB-2)

    37. 222 kN (50 kip) Dog Bone – Good Performance (50DB-1)

    38. 222 kN (50 kip) Dog Bone – Good Performance (50DB-1)

    39. 556 kN (125 kip) Perforated – Good Performance (125P-5)

    40. 556 kN (125 kip) Perforated – Good Performance (125P-5) 1st 2 perforations @ each end completely blocked, middle 4 perforations blocked with steel plate minus 2 in. length, minus ˝ in. width Compressive stiffening due to completely blocked end perforations

    41. 222 kN (50 kip) Perforated – Good Performance (50P-1)

    42. 222 kN (50 kip) Perforated – Good Performance (50P-1) 1st 2 perforations @ each end blocked with steel plate minus 1 in. length, middle 4 perforations blocked with steel plate minus 1 in. length, minus ˝ in. width On large cycles compressive stiffening is from legs coming in contact with confining tube

    43. Conclusions Properly designed, detailed, and constructed CYD device exhibits reasonably stable and symmetric hysteretic response Performance is confining media dependent Extending the unreduced length of steel yielding core further into the confining tube would help to reduce local buckling at the end of the yielding core Reducing the perforation leg length would limit the necessity for perforation blocking Yielding core cross-sectional area and mechanical properties can be tailored to provide a device with desired strength and stiffness.

    44. Acknowledgments This research is funded by the National Science Foundation (NSF) under Grant No. CMS-0099701 as part of the US-Japan Cooperative Research in Urban Earthquake Disaster Mitigation Program. Professor K. Kasai of the Tokyo Institute of Technology is the Japanese counterpart and Dr. Peter Chang is the program manager. Additional funding from the 2002 AISC/Klingelhofer Fellowship supported this research. Their support is gratefully acknowledged. The opinions, findings, and conclusions are those of the authors and do not necessarily reflect the views of NSF, AISC, or the individuals acknowledged above.

More Related