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Tools for Isolation and Protective Systems

Tools for Isolation and Protective Systems. NEES TIPS/E-Defense Tests of a Full Scale Base-Isolated and Fixed-Base Building. Keri L. Ryan Assistant Professor/ University of Nevada, Reno NEES TIPS Principal Investigator. Quake Summit 2012. Boston, Massachusetts, July 12, 2012.

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Tools for Isolation and Protective Systems

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  1. Tools for Isolation and Protective Systems NEES TIPS/E-Defense Tests of a Full Scale Base-Isolated and Fixed-Base Building Keri L. Ryan Assistant Professor/ University of Nevada, Reno NEES TIPS Principal Investigator Quake Summit 2012 Boston, Massachusetts, July 12, 2012

  2. Tools for Isolation and Protective Systems Project Collaborators US/NEES Researchers Japan/NIED Researchers • Prof. Keri Ryan (University of Nevada, Reno) • Prof. Stephen Mahin(UC Berkeley) • Prof. Gilberto Mosqueda(U. Buffalo) • Prof. Manos Maragakis(University of Nevada, Reno) • Prof. Kurt McMullin(San Jose State University) • Prof. Troy Morgan (Tokyo Tech.) • Prof. Kazuhiko Kasai (Tokyo Tech.) • Prof. ArashZaghi(U. Conn) • Dr. Eiji Sato (NIED) • Dr. Tomohiro Sasaki (NIED) • Prof. Taichiro Okazaki (Hokkaido University) • Prof. Masayoshi Nakashima (Kyoto University) • Dr. Koichi Kajiwara(NIED) Quake Summit 2012 Boston, Massachusetts, July 12, 2012

  3. Tools for Isolation and Protective Systems Project Collaborators Industry Collaborators/Sponsors Students • Earthquake Protection Systems • Dynamic Isolation Systems • Aseismic Design Company • Takenaka Corporation • USG Building Systems • Hilti Corporation • CEMCO Steel • Victaulic • Tolco • Nhan Dao • Keisuke Sato • Camila Coria • SiavashSoroushian Quake Summit 2012 Boston, Massachusetts, July 12, 2012

  4. Tools for Isolation and Protective Systems Scope of Test Program • Shake table tests of 5-story steel moment frame building in 3 different configurations • isolated with triple friction pendulum bearings (TPB) • Isolated with lead-rubber bearings and cross linear bearings (LRB/CLB) • “fixed-base” configuration • Evaluate response of the structure, nonstructural components, and contents for all configurations Quake Summit 2012 Boston, Massachusetts, July 12, 2012

  5. Tools for Isolation and Protective Systems Triple Pendulum (TPB) Test Objectives • Demonstrate seismic resiliency of the system in a very large event. Provide continued functionality and minimal disturbance to contents. Quake Summit 2012 Boston, Massachusetts, July 12, 2012

  6. Tools for Isolation and Protective Systems Lead Rubber (LRB/CLB) Test Objectives • Evaluate performance of an elastomeric isolation system designed for a nuclear power plant in beyond design basis shaking • Designed for “Vogtle”, a representative central and eastern U.S. soil site • Performance Objectives for Bearings • Sustain large displacement demands • Retain axial load carrying capacity at these large displacements Quake Summit 2012 Boston, Massachusetts, July 12, 2012

  7. Tools for Isolation and Protective Systems Other Test Objectives • Extend resiliency to systems with challenging configurations • Lightweight structure (500 tons) • Demonstrate torsion reduction in an asymmetric building Asymmetry of system enhanced with asymmetric steel plates attached at roof for added mass. The roof was designed for the extra load, which could represent combined load of roof mounted equipment, roof penthouse, etc. Quake Summit 2012 Roof Plan Boston, Massachusetts, July 12, 2012

  8. Tools for Isolation and Protective Systems Triple Pendulum (TPB) Isolators and Configuration 9 isolators, one beneath each column 1.4 m (55 in) .33 m (13 in) Quake Summit 2012 Boston, Massachusetts, July 12, 2012

  9. Tools for Isolation and Protective Systems Lead Rubber (LRB/CLB) Isolation System • Lead Rubber Bearings • 70 cm (27.5 in) diameter • 4 bearings -> TD = 2.8 sec • Capacity of 50 tons at 60 cm • Cross Linear Sliders • Flat slider with 0.25% cof • Tension resistance • Carries weight at large displacements Quake Summit 2012 Boston, Massachusetts, July 12, 2012

  10. Tools for Isolation and Protective Systems LRB/CLB System Configuration 5 cross linear bearings 4 lead rubberbearings Quake Summit 2012 Boston, Massachusetts, July 12, 2012

  11. Tools for Isolation and Protective Systems Characteristics of Each System Triple Pendulum LRB/CLB T2=5.57s 0.37W T2=2.78s 0.275W 0.214W 0.080W 0.053W 0.020W Teff=2.55s Teff=4.55s T1=1.84s • Yield Force = 0.08W • T2 = 5.57 sec • Disp. Capacity = 1.14 m (45 in) • Yield Force = 0.053W • T2 = 2.78 sec • Disp. Capacity = 0.6 m (24 in) Quake Summit 2012 Boston, Massachusetts, July 12, 2012

  12. Tools for Isolation and Protective Systems Innovation to Capture Forces in Isolators Force-deformation of full scale isolators in a system test captured for the first time! • 9 custom-made steel plate load cell assemblies, each using 7 or 9 distributed load cells to absorb axial forces from overturning Quake Summit 2012 Boston, Massachusetts, July 12, 2012

  13. Tools for Isolation and Protective Systems Superstructure Modeling • 3D frame model built in OpenSees • Beams and slabs modeled as composite sections • Rigid diaphragm constraint • Mass lumped to every node of the model • Beams divided into several elements for distributing mass to model Quake Summit 2012 Boston, Massachusetts, July 12, 2012

  14. Tools for Isolation and Protective Systems Modeling of Columns • Displacement-based distributed plasticity elements with fiber sections; 3 elements per column • GiuffreMenegotto Pinto steel material Quake Summit 2012 Boston, Massachusetts, July 12, 2012

  15. Concrete Steel Tools for Isolation and Protective Systems Modeling of Beams • Displacement-based distributed plasticity element with resultant sections; 8 elements per beam • Resultant section behavior developed from section analysis of composite section • Effective slab width = L/8 in each direction Quake Summit 2012 Boston, Massachusetts, July 12, 2012

  16. Spring representing panel web Rigid element Panel web Hinge Beam Beam Column Column Spring representing column flanges Tools for Isolation and Protective Systems Beam to Column Connections • Krawinkler panel zone model • Assemblage of rigid links and rotational springs Quake Summit 2012 Boston, Massachusetts, July 12, 2012

  17. Tools for Isolation and Protective Systems Damping in Superstructure • Rayleigh Damping used for both isolated and fixed-base • Damping anchored at 2.2% at 0.7 sec and 0.15 sec for fixed-base • Damping anchored at 1.5% at 2.0 sec and 2.5% at 0.15 sec for isolated • Supplemental damper was added from base to roof to increase damping across first structural mode Quake Summit 2012 Boston, Massachusetts, July 12, 2012

  18. Element 1 Element 2 Element 3 Element 6 Element 5 Element 4 Tools for Isolation and Protective Systems Modeling of TPB • Model assembled elastic-plastic springs and gap elements in series to represent stages of sliding • Bi-directional coupling (circular gap element) • Horizontal-vertical coupling Quake Summit 2012 Boston, Massachusetts, July 12, 2012

  19. Tools for Isolation and Protective Systems Dynamic Variation of Friction Coefficient • Bearing formulation incorporates variation of friction coefficient with axial force and velocity • μ average = 9.8% Axial Force Effect Velocity Effect Quake Summit 2012 Boston, Massachusetts, July 12, 2012

  20. Tools for Isolation and Protective Systems Calibrated Model for Sine Wave Test • Generalized friction model incorporating axial force and velocity effects more closely matches the test data than a constant friction model Generalized Friction Model Constant Friction Model Quake Summit 2012 Boston, Massachusetts, July 12, 2012

  21. Tools for Isolation and Protective Systems Model Verification for 100% Tabas • Peak displacement: Test = 0.691 m, Model = 0.677 m • Generalized friction model predicted the peak displacement better than constant friction models. Displacement Trace Bearing Hysteresis Quake Summit 2012 Boston, Massachusetts, July 12, 2012

  22. Tools for Isolation and Protective Systems Modeling of LRB/CLB Force • Bilinear force-deformation in horizontal direction with bidirectional coupling • Bilinear elastic response in vertical direction with different stiffnesses in tension and compression • Horizontal and vertical behavior were uncoupled Kd Fy K1 Displacement Quake Summit 2012 Boston, Massachusetts, July 12, 2012

  23. Tools for Isolation and Protective Systems Characterization of LRB Diablo Canyon 95% • Because of amplitude dependence, bearing parameters were characterized independently for every test Westmorland 80% Force (kN) Peak Disp = 8.8 cm QD = 33.4 kN kD = 11.0 kN/cm Disp. (mm) Force (kN) Peak Disp = 54.7 cm QD = 70.3 kN kD = 6.2 kN/cm Quake Summit 2012 Boston, Massachusetts, July 12, 2012 Disp. (mm)

  24. Tools for Isolation and Protective Systems Model Verification for 95% Diablo Canyon • Even rigorous characterization led to mixed results for displacement prediction. • Model optimized for peak cycle gave poor results for smaller cycles. • Trial and error adjustments were made. Quake Summit 2012 Boston, Massachusetts, July 12, 2012

  25. Tools for Isolation and Protective Systems Floor Acceleration Response in LRB/CLB System, XY vs 3D Motion (Vert. PGA = 0.7g) Quake Summit 2012 Boston, Massachusetts, July 12, 2012

  26. Analysis of Floor Spectra, LRB System XY Input Mode 1 Floor Spectra for Diablo Canyon 95%, x-direction Floor 1 Floor 2 Floor 3 Isolation Mode T = 2.72 sec Mode 5 Acceleration (g) Floor 4 Floor 5 Floor 6 1st Structural Mode T = 0.36 sec Period (sec)

  27. Analysis of Floor Spectra, LRB System XY Input Floor Spectra for Diablo Canyon 95%, x-direction Floor 1 Floor 2 Floor 3 Mode 8 Acceleration (g) Floor 4 Floor 5 Floor 6 2nd Structural Mode T = 0.17 sec Period (sec)

  28. Floor Spectra XY vs. 3D Input, LRB System X-direction F1 F2 F3 Acceleration (g) F4 F5 F6 Y-direction Additional peaks in y-direction for 3D input F1 F2 F3 Acceleration (g) F4 F5 F6

  29. Analysis of Floor Spectra, LRB System 3D Input Floor Spectra for Diablo Canyon 80%, y-direction Floor 1 Floor 2 Floor 3 3rd Structural Mode Y-direction T = 0.1 sec Acceleration (g) Floor 4 Floor 6 Floor 5 3rd Structural Mode X-direction T = 0.1 sec Period (sec)

  30. Tools for Isolation and Protective Systems Floor Acceleration Response in TPB System, XY vs. 3D Motion Quake Summit 2012 Boston, Massachusetts, July 12, 2012

  31. Tools for Isolation and Protective Systems Floor Acceleration Response in TPB System, 3D Takatori (Vert. PGA = 0.28g) Mode 8 • The acceleration profile in X-dir follows the 2nd structural mode. 2nd Structural Mode T = 0.17 sec Quake Summit 2012 Boston, Massachusetts, July 12, 2012

  32. Analysis of Floor Spectra, TPB System 3D Input Floor Spectra for Takatori 100%, x-direction Mode 8 2nd Structural Mode T = 0.17 sec

  33. Tools for Isolation and Protective Systems Base Shear in TPB System, 3D Takatori (Vert. PGA = 0.28g) • Oscillation at 7 Hz (0.14 sec) due to vertical acceleration is transmitted to the base shear, and amplifies the second structural mode. Quake Summit 2012 Boston, Massachusetts, July 12, 2012

  34. Tools for Isolation and Protective Systems Concluding Remarks • Rigorous analysis clarified interesting (unexpected) findings regarding the behavior of the isolated buildings. • A 3D TPB model that includes dynamic variation of friction coefficient with axial force and velocity can predict the displacement demand very well. • The damping in the steel structure (remaining linear) was very low; a damping ratio between 1-2% in all modes is recommended. Participation of higher modes was greater than expected. • Under vertical ground input, horizontal floor accelerations were amplified due to modal coupling in the structure and axial-shear coupling in the TPB bearings. Time history analysis of the system with 3D input is essential to understand and predict these effects, which were significant in the tests. 2012 Structures Congress Chicago, Illinois, March 29-31, 2012

  35. Tools for Isolation and Protective Systems Thanks to the many sponsors! • National Science Foundation NEES Program • (Grant No. CMMI-1113275 and CMMI-0721399) • Nuclear Regulatory Commission • Earthquake Protection Systems • Dynamic Isolation Systems, Aseismic Devices Company, Sumiken Kansai, THK • Takenaka Corporation • USG Building Systems, CEMCO Steel, Victaulic, Tolco, Hilti • Japan Society for the Promotion of Science (JSPS) 2012 Structures Congress Chicago, Illinois, March 29-31, 2012

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