Overview of International Cooperative Research on Seismic Performance of Composite and Hybrid Structures

Abstract

Innovative combinations of two or more materials can result in very efficient and high performing structural systems to resist severe forces due to events such as earthquakes. During the past two decades or so, significant gains in the knowledge base regarding the seismic behavior of composite and hybrid structural components and systems have been made. Much of this has been accomplished through international cooperative res earch programs. This paper presents an overview of two such major programs: The US-Japan Research Program which spanned over a period approximately seven years from 1993-2000, followed by the US-Taiwan Cooperative Research Program which started in 2001 and is currently in progress. While the US -Japan Program was significantly broader in scope and magnitude, greater emphasis was placed on component and sub-assemblage studies and testing of f ull scale structures could not be undertaken due to time and budget limitations. The US -Taiwan Program was designed to fill this gap, by undertaking testing of two full size three story, three bay frames at the National Center for Research in Earthquake Engineering (NCREE), Taiwan, accompanied by related sub-assemblage tests at participating research institutions in Taiwan and analytical and design implication studies in the US. The two structural systems selected for the US -Taiwan program are: RC column- steel beam (RCS) moment frames, and concrete-filled tubular columns-steel beams-buckling restrained composite braced frames (CFT-BRBF). A five-year research program on Composite and Hybrid Structures as Phase 5 of the U.S. -Japan Cooperative Earthquake Research Program was recommended to be initiated in 1993 in both countries. The research work in Japan started in fiscal year 1993. However, fuller participation of researchers on both sides started in early summer 1995. The sponsorship of the program was by the National Science Foundation in the U.S. and by the Ministry of Construction along with a number of industry groups in Japan. This paper presents a brief overview of the program and accomplishments made on both sides. Because of diverse and broad scope of the subject area, the research program was organized into the following four groups: Concrete Filled Tube Column Systems (CFT); Reinforced Concrete (RC) and Steel Reinforced Concrete (SRC) Column Systems (RCS); RC/SRC Hybrid Wall Systems (HWS); and New Materials, Elements and Systems (RFI). A theme structure with well selected layout, geometry and design loads provided a common focus for various systems that were studied, and also a common prototype structure from which the components and sub-assemblages were drawn. U.S.-Japan Program The U.S.-Japan Cooperative Earthquake Research Program began in 1979 under the auspices of the UJNR Panel on Wind and Seismic Effects. The overall objective of the total program was to improve seismic safety practices in bot h countries through cooperative studies to determine the