Presentation by Valentin Shustov 20 June, 2007

1. 5th NEES Annual Meeting Earthquake Protector a new line of base isolation under shake table testing and analysis Presentation by Valentin Shustov 20 June, 2007

2. NEES-UCSD Web Portal https://central.nees.org/activities/index.php?facility=UCSD

3. Exploratory Research • The latest research activities at CSUN culminated in the innovative building technology called the Earthquake Protector. Its research, supported by NSF, Award No. 0618183, and entitled “SGER: Testing of a New Line of Seismic Base Isolators” is both analytical and experimental. For the Final Report to NSF, click on https://central.nees.org/data/get/NEES-2006-0283/Public/REPORT.pdf • The reported research contains a lot of novelties including but not limited to the very concept of earthquake protection, metrics of building performance, physical and virtual experiments, hardware, software and, of course, conclusions. • Software for analytical research called Earthquake Performance Evaluation Tool (EPET) enables virtual experiments on buildings with and without Earthquake Protectors. On demand, all virtual experiments are animated. • Major building earthquake performance evaluation parameter for the testing is the Seismic Performance Ratio.

4. Physical model Mathematical model Building Modeling Building models are the primary measuring tool in all experiments.

5. where Quality FactorRw is understood as the ratio of the ultimate allowable story drift vu that can be tolerated by the structure without a collapse to the maximum elastic story drift ve. For assessment or comparison of the anticipated building performance, the Story Performance RatingR will be used as a major criterion: R = (1) where v = un - un-1 is an actual or calculated inter-story drift; ve is an inter-story drift at the assumed elastic limit of horizontal deformation. The ultimate allowable value of R will occur when R = Rw = (2) Performance Criteria

6. The case R < 1 relates to a purely elastic performance of the structure. The case 1 < R < Rw defines how far the structure extends into the plastic range. The case R > Rw means a possibility of either collapse of the story or occurrence of other life threatening damage that will not, necessarily, result in losing full value of the structure. Ratio R/Rwis the Seismic Performance Ratio which controls the anticipated physical losses due to seismic exposure of the building structure. The anticipated damage due to a seismic exposure is defined by the Damage RatioD.R. that may be related to R/Rw. Performance Scenarios

7. Road Map to Earthquake Protector http://www.ecs.csun.edu/~shustov/000-EPF.html http://www.ecs.csun.edu/~shustov/EP-2004-1.htm 1 3 video video http://www.ecs.csun.edu/~shustov/001-EPF-03.html http://www.ecs.csun.edu/~shustov/EP-2005.htm 2 4 video video

8. UCSD Shake Table Main technical characteristics of the facility: • Platen 7.6 m x 12.2 m • Stroke 0.75 m • Frequency 0-20 Hz • Peak velocity 1.8 m/s • Force capacity 6.8 MN • Vertical payload 20 MN Performance testing of Earthquake Protectors took place at the UC San Diego Large High Performance Outdoor Shake Table (LHPOST). LHPOST is a participant of the George E. Brown Jr. Network for Earthquake Simulation (NEES).

9. Three 1/8th–scaled down building models of identical design were tested on the shake table, namely: 6-story, 12-story and 18-story ones. Those models were kinematically equivalent to the real building prototypes which meant they would deflect horizontally the same way under the same horizontal excitation. The “prestressing” concept of design was chosen to increase the models’ structural redundancy while preserving their visual sensitivity to any kind of lateral excitations. Building Models

10. What is the purpose of EP? • Earthquake Protector or EP (U.S. Patent pending) is a system of structural elements resting on a building footing and underpinning a building superstructure. • This system, generically called base isolation, is intended to shield the building superstructure against lateral impacts of strong earthquakes. • To withstand the real earthquake time-histories, the models of earthquake protectors had to have full scale horizontal dimensions. • Unlike the active, hybrid or semi-active structural control hardware, it looks, apparently, simple and self-sufficient .

11. Components of EP • a column stub 7 resting upon a spherical bearing 9 mounted centrically on the upper pad 3 with the top end of the column stub being framed rigidly into the supported superstructure 8. Each EP comprises: • Three properly configured race pads 1, 2 and 3 mounted one over another with the lower pad 1 resting on the footing. • Two circular-cylinder-shaped segmented slide tracks 4 and 5 which are sagged down, located between adjacent race pads and containing freely revolving parallel cylindrical rollers 6 with their axes being set horizontal and mutually orthogonal.

12. Preparation for Testing • The 6-story building model supported on four Earthquake Protectors: • Assembly of four Earthquake Protectors in the process of assembly:

13. Performance Demonstration http://www.ecs.csun.edu/~shustov/EP-2006.htm video

14. Performance of Building Models on EP Ground acceleration mitigation factor Fmit , that is the most simple performance parameter chosen for comparison with the field records, may be determined as a ratio of the maximum recorded horizontal acceleration on the ground (or on the shake table platen) to the maximum recorded horizontal acceleration on the building (or on the model structure).

15. Performance of Base-Isolated Structures in California See http://www.ecs.csun.edu/~shustov/Topic4.htm

16. Promise vs. Performance See http://www.ecs.csun.edu/~shustov/Topic2.htm 1 - LA County Fire Command Facility 2 - USC Teaching Hospital 3 - 3-story Residence Building 4 - Rockwell Intl. Headquarters

17. Earthquake Performance Evaluation Tool The software development source code: http://epet.space3d.biz/EPET_DEV.zip. • Software for analytical research called Earthquake Performance Evaluation Tool (EPET) enables virtual experiments on buildings with and without Earthquake Protectors. On demand, all virtual experiments are animated. • Major building fitness evaluation parameter for the testing is the Seismic Performance RatioR/Rw.

18. Virtual Performance Evaluation • Quantitative performance evaluation of a virtual building structure during a virtual earthquake excitation is done with the help of the nth story Seismic Performance RatioR/Rw(or SPR): SPR = vn/Rwnven (3) • There will be the following three basic situations: • 0 < SPR < 1 Acceptable performance of a story, called: GOOD. • 1 < SPR < 1.5 Possibility of structural failure, called: FAILURE. • 1.5 < SPR Structural collapse, called: СOLLAPSE.

19. 6-story Models Comparative Testing http://www.ecs.csun.edu/~shustov/TEST_8_LARGE.wmv video video

20. Comparative Drifts Table

21. Comparative Damage Table

22. 12-story Models Comparative Testing http://www.ecs.csun.edu/~shustov/TEST_5_LARGE.wmv 1 video

23. 12-story Models Comparative Testing http://www.ecs.csun.edu/~shustov/TEST_6_LARGE.wmv 2 video

24. Comparative Performance Table

25. Conclusions • Shake table experiments with Earthquake Protectors performed on the scaled-down building models were a full success. • The stronger an earthquake the better Earthquake Protector’s mitigating performance. • Taking ground acceleration mitigation factorFmit as a criterion for performance comparison of different types of base isolators, Earthquake Protector is, at least, five times more effectively than any of the field-tested seismic base isolator in California. • Earthquake Protector is simple, inexpensive to build and applicable to any size of the building structure. • Earthquake Performance Evaluation Tool (EPET) can accurately predict earthquake performance of a building, with or without Earthquake Protector, up to the point of its virtual state of “severe damage”. video