EARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS Earthquake Engng Struct. Dyn. 2005; 34:1407–1425 Published online 1 June 2005 in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/eqe.494 Online hybrid test by internet linkage of distributed test-analysis domains Peng Pan 1; ‡ , Motohide Tada 2; § and Masayoshi Nakashima 3; ∗; †; ¶ 1 Department of Architecture and Architectural Engineering; Kyoto University; Katsura; Nishikyoku; Kyoto 615-8540; Japan 2 Department of Architectural Engineering; Graduate School; Osaka University; Suita; Osaka 565-0871; Japan 3 Disaster Prevention Research Institute; Kyoto University; Gokasho; Uji; Kyoto 611-0011; Japan SUMMARY Online hybrid tests (called the online tests), particularly when combined with substructuring techniques, are able to conduct large-scale tests. An extension of this technique is to combine multiple loading tests conducted in remote locations and to integrate the tests with large numerical analysis codes. In this study, a new Internet online test system is developed in which a physical test is conducted in one place, the associated numerical analysis is performed in a remote location, and the two locations communicate over the Internet. To implement the system, a technique that links test and analysis domains located at dierent places is proposed, and an Internet data exchange interface is devised to allow data communication across Internet. A practical method that utilizes standard protocols implemented by operating systems for sharing les and folders is adopted to ensure stable and robust communication between remotely located servers that commonly protect themselves by strict rewalls. To combine the online test with a nite element program formulated in an incremental form and adopting an implicit integration scheme, a tangent stiness prediction procedure is proposed. In this procedure, a tangent stiness is estimated based on a few previous steps of experimental data. Using the system devised, tests on a base-isolated structure were carried out. Here, the base-isolation layer was taken as the tested part and tested in Kyoto University, Japan, and the superstructure was modelled by means of a nite element program and analysed in a computer located in Osaka University. A series of physical Internet online tests were carried out, with the integration time interval and the method of tangent stiness prediction as the major parameters. The tests demonstrated that the Internet communication was very stable and robust, without malfunctions. The proposed method of stiness prediction was eective even when the experimental hysteresis curves exhibited complex behaviour, thereby ensuring accurate simulation for the earthquake response of the entire structure. Copyright ? 2005 John Wiley & Sons, Ltd. KEY WORDS: hybrid test; Internet; substructuring; stiness prediction; nite element method; base- isolation ∗ Correspondence to: Masayoshi Nakashima, Disaster Prevention Research Institute, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan. † E-mail: nakashima@archi.kyoto-u.ac.jp ‡ JSPS Postdoctoral Fellow. § Associate Professor. ¶ Professor. Received 9 July 2004 Revised 17 February 2005 Copyright ? 2005 John Wiley & Sons, Ltd. Accepted 17 February 2005