Tools for Isolation and Protective Systems Quake Summit 2012 Boston, Massachusetts, July 12, 2012 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

Tools for Isolation and Protective Systems Quake Summit 2012 Boston, Massachusetts, July 12, 2012 Project Collaborators 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. Arash Zaghi (U. Conn) Dr. Eiji Sato (NIED) Dr. Tomohiro Sasaki (NIED) Prof. Taichiro Okazaki (Hokkaido University) Prof. Masayoshi Nakashima (Kyoto University) Dr. Koichi Kajiwara (NIED) Japan/NIED ResearchersUS/NEES Researchers

Tools for Isolation and Protective Systems Quake Summit 2012 Boston, Massachusetts, July 12, 2012 Project Collaborators 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 Siavash Soroushian StudentsIndustry Collaborators/Sponsors

Tools for Isolation and Protective Systems Quake Summit 2012 Boston, Massachusetts, July 12, 2012 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 Scope of Test Program

Tools for Isolation and Protective Systems Quake Summit 2012 Boston, Massachusetts, July 12, 2012 Specimen Tested Steel moment frame w/ box columns and wide flange beams 12x10 m in plan, 16 m tall W = 5000 kN (1100 kip) Period T = 0.7 sec (from testing) Strength from pushover anal. – First plastic hinging ~ 3500 kN (0.7W) Not precise – Full mechanism strength ~ 5500 kN (1.05W) Specimen was tested extensively in March 2009 Value Added Building Project

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

Tools for Isolation and Protective Systems Quake Summit 2012 Boston, Massachusetts, July 12, 2012 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

Tools for Isolation and Protective Systems Quake Summit 2012 Boston, Massachusetts, July 12, 2012 Other Test Objectives Extend resiliency to systems with challenging configurations o Lightweight structure (500 tons) o Demonstrate torsion reduction in an asymmetric building Roof Plan 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.

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

Tools for Isolation and Protective Systems Quake Summit 2012 Boston, Massachusetts, July 12, 2012 Lead Rubber (LRB/CLB) Isolation System Lead Rubber Bearings 70 cm (27.5 in) diameter 4 bearings -> T D = 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

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

Tools for Isolation and Protective Systems Quake Summit 2012 Boston, Massachusetts, July 12, 2012 Characteristics of Each System 0.020W 0.080W T 1 =1.84s T 2 =5.57s T eff =4.55s 0.214W 0.275W 0.053W 0.37W T 2 =2.78s T eff =2.55s Yield Force = 0.08W T 2 = 5.57 sec Disp. Capacity = 1.14 m (45 in) Triple PendulumLRB/CLB Yield Force = 0.053W T 2 = 2.78 sec Disp. Capacity = 0.6 m (24 in)

Tools for Isolation and Protective Systems Quake Summit 2012 Boston, Massachusetts, July 12, 2012 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

Tools for Isolation and Protective Systems Quake Summit 2012 Boston, Massachusetts, July 12, 2012 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

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

Tools for Isolation and Protective Systems Quake Summit 2012 Boston, Massachusetts, July 12, 2012 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 Concrete Steel

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

Tools for Isolation and Protective Systems Quake Summit 2012 Boston, Massachusetts, July 12, 2012 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

Tools for Isolation and Protective Systems Quake Summit 2012 Boston, Massachusetts, July 12, 2012 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 Element 1 Element 4 Element 2 Element 5 Element 3 Element 6

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

Tools for Isolation and Protective Systems Quake Summit 2012 Boston, Massachusetts, July 12, 2012 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 Constant Friction ModelGeneralized Friction Model

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

Tools for Isolation and Protective Systems Quake Summit 2012 Boston, Massachusetts, July 12, 2012 Modeling of LRB/CLB 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 Displacement Force K1K1 KdKd FyFy

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

Tools for Isolation and Protective Systems Quake Summit 2012 Boston, Massachusetts, July 12, 2012 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.

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

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

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

Floor Spectra XY vs. 3D Input, LRB System X-direction Y-direction Acceleration (g) F1F2F3 F4 F5F6 F1 F2F3 F4F5F6 Additional peaks in y- direction for 3D input

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

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

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

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

Tools for Isolation and Protective Systems Quake Summit 2012 Boston, Massachusetts, July 12, 2012 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.

Tools for Isolation and Protective Systems 2012 Structures Congress Chicago, Illinois, March 29-31, 2012 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.

Tools for Isolation and Protective Systems 2012 Structures Congress Chicago, Illinois, March 29-31, 2012 Thanks to the many sponsors! National Science Foundation NEES Program – (Grant No. CMMI and CMMI ) 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)