Three experimental methods dominate laboratory research on the seismic performance of structural systems — shake table tests, quasi-static tests, and hybrid simulation. (See: M.S. Williams and A. Blakeborough, “Laboratory testing of structures under dynamic loads: an introductory review” in Theme Issue ‘Dynamic testing of structures’ compiled by M.S. Williams; Philosophical Transactions A of the Royal Society. September 15, 2001; 359 (1786). Costs of shake table tests (especially to avoid scaling problems) and the dynamic limits of most static testing procedures have propelled cost-effective hybrid simulation test methods. Hybrid simulation techniques combine physical, experimental testing of subassemblages (substructured components that can be full-scale) under simulated earthquake loadings with simultaneous numerical simulations of multiple other substructures into one model. Subassemblages tested experimentally are usually portions of the structure that are very difficult to model numerically, while components with predictable behavior are modeled on the computer.
Current and Future Hybrid Simulation Capabilities (from Mosalam - 2012)
The first operational hybrid simulated testing in earthquake engineering occurred 40 years ago at the University of Tokyo. (See – Takanashi, Koichi. Non-linear earthquake response analysis of structures by a computer-actuator on-line system (detail of the system)
; article first published in English in: Bulletin of Earthquake Resistant Structure Research Center
(The Institute of Industrial Science, University of Tokyo), No.8, December, 1974. p.1-17., 1975; and subsequently, Takanashi, Koichi and Nakashima, M. “Japanese activities on on-line testing
” Journal of Engineering Mechanics, ASCE
, 113 (7) : July, 1987 p. 1014-1032.)
The hybrid simulation testing techniques of analytical simulation and substructure testing methods are rooted in the development of ‘pseudo-dynamic testing’ methods (See: Shing, Pui-shum B.; Mahin, Stephen A. Experimental error propagation in pseudodynamic testing. UCB/EERC-83/12, Earthquake Engineering Research Center, University of California, Berkeley, 1983-06, 175 pages. ; Shing, Pui-shum B.; Mahin, Stephen A. Pseudodynamic test method for seismic performance evaluation: theory and implementation. UCB/EERC-84/01, Earthquake Engineering Research Center, University of California, Berkeley, 1984-01, 162 pages ; Dermitzakis, Stavros N.; Mahin, Stephen A. Development of substructuring techniques for on-line computer controlled seismic performance testing. UCB/EERC-85/04, Earthquake Engineering Research Center, University of California, Berkeley, 1985-02, 153 pages ; Thewalt, Christopher R.; Mahin, Stephen A. Hybrid solution techniques for generalized pseudodynamic testing. UCB/EERC-87/09, Earthquake Engineering Research Center, University of California, Berkeley.) This continuous development of substructuring techniques, significant improvements in control technology, and repeated experimental implementation resulted in successful geographically-distributed hybrid simulation tests by early 2000s, (See – Mosqueda, Gilberto; Stojadinovic, Bozidar; Mahin, Stephen A. Continuous hybrid simulation with geographically distributed substructures. UCB/EERC-2005/02, Earthquake Engineering Research Center, University of California, Berkeley, 2005-11, 168 pages) as well as the emergence at UC Berkeley of the Open System for Earthquake Engineering Simulation – OpenSees - and the Open-source Framework for Experimental Setup and Control – OpenFresco - , open source software that support hybrid simulation for seismic performance testing.
Seismic performance testing using hybrid simulation techniques is now in wide use. Some widely drawn examples include : [US-Japan] Peng Pan, Hiroshi Tomofuji, Tao Wang, Masayoshi Nakashima, Makoto Ohsaki, Khalid M. Mosalam. “Development of peer-to-peer (P2P) internet online hybrid test system.” Earthquake Engineering & Structural Dynamics, Volume 35, Issue 7, pages 867–890, June 2006. [China] Jiang Wang, Jin-Ting Wang , Feng Jin, Fu-Dong Chi, Chu-Han Zhang. “Real-time dynamic hybrid testing for soil–structure interaction analysis.” Soil Dynamics and Earthquake Engineering. Volume 31, Issue 12, December 2011, Pages 1690–1702. [Europe] F. J. Molina, G. Magonette and B. Viaccoz . Linear Model of a Pseudo-Dynamic Testing System. European Commission, Joint Research Centre (JRC) Scientific and Technical Reports , IPSC, ELSA Laboratory, Ispra (VA), Italy. 2002; Santacana, Ferran Obón; Dorka, Uwe E. “Effects of large numerical models in continuous hybrid simulation.” Lisboa, Portugal. WCEE, 2012, paper presented at 15th World Conference on Earthquake Engineering; Tsitos, A. C.; Bousias, S.; Dimitropoulou, E. “Hybrid testing of bridge structures supported on elastomeric bearings.” Lisboa, Portugal. WCEE, 2012, paper presented at 15th World Conference on Earthquake Engineering; [USA] Nakata, Narutoshi; Elnashai, A. S.; Spencer, Billie F. “Multi-dimensional mixed-mode hybrid simulation control and applications.” University of Illinois at Urbana-Champaign, Newmark Structural Engineering Laboratory Report Series 005, 2007-12; [Canada] Kammula, V.; Erochko, J.; Kwon, O.; Christopoulos, Constantin. “Performance assessment of the self centering energy dissipative (SCED) bracing system using hybrid simulation.” Lisboa, Portugal. WCEE, 2012, paper presented at 15th World Conference on Earthquake Engineering.