Following the symposium on Hybrid and Composite Construction and after receiving the papers for the proceeding volume, the committee decided that in addition to the presented papers, it will add considerably to the value of the volume, if there was an opening paper to present an overview as well as the future predictions of the whole system. Mr. Viest, known in this field for a long time, was invited to do this difficult task. In his presentation, Mr. Viest reviews the past and the present, and concludes with some future directions, which hybrid and composite construction might take.

The earthquake that shook southern Hyogo Prefecture in Japan on January 17, 1995 (also known as the Kobe earthquake) measured 7.2 on the Richter Scale. This event was the most devastating earthquake to strike Japan since the Kanto earthquake of 1923. This paper focuses on the performance of a particular composite system, referred to as Steel Reinforced Concrete (SRC). This type of structural system comprises approximately 10 percent of all square meters of construction in Japan. A major factor contributing to the collapse of many SRC buildings, known to Japanese researchers prior to the earthquake, could be said to be the lack of adequate confining steel and cross ties, especially for large columns. Additionally, the use of 90 degree hooks, even with close tie spacing, was shown to be undesirable.

Design of composite structures for earthquake loading has to address different problems to static design, as the advantageous greater damping may be offset by the disadvantage of increased mass and stiffness, leading to higher seismic loads. However, since composite construction is used extensively, especially for high-rise construction, the seismic performance of this form of structure requires investigation and the development of specific design guidance. European work over the past ten years or so confirmed that, with minimum design and detailing alterations, composite structures offer a most economical and reliable design alternative to steel and reinforced concrete structures. This paper reviews some of the European work on composite members. Particular emphasis is placed on work at Imperial College, since this was mostly carried out by the writer and his co-researchers. The work on a novel type of composite member is described,with special emphasis on ductility-based design recommendations. This is followed by a discussion of the role of composite beam-column connections and beam members in providing lateral stiffness, resistance and energy dissipation. Hierarchical assessment limit states are defined and are used to arrive at earthquake yield and ultimate response accelerations. These are used to calculate analytical behaviour factors of typical composite frames, which are shown to be more economical than steel frames designed for the criteria. Finally, brief comments regarding current and future work on seismic resistance of composite structures in Europe are given.

Composite and Hybrid Structures (CHS) provide many advantages over those employing conventional systems. Since the available design codes in Japan do not cover these systems, the current Japanese Building Standard Law requires detailed experimental and/or analytical studies before the building permit for a structure with CHS can be issued. As part of the U.S.-Japan Cooperative Earthquake Research Program on Composite and Hybrid Structures, three major types of composite and hybrid systems are being studied. These include concrete-filled tubular columns (CFT), reinforced concrete columns with steel beams (RCS), and reinforced concrete cores with steel perimeter frames (HWS). Among other objectives, these studies are expected to lead to design guidelines which can be incorporated in the Building Standard Law. The availability of these guidelines are expected to encourage the Japanese designers to use CHS more frequently. This paper provides an overview of the ongoing studies in Japan. After a brief historical review of each system, the important issues related to each system are summarized. Planned and ongoing studies for each group of composite systems are also described.

Strengthening existing concrete members using externally bonded steel plates (BSP) is an effective method of enhancing both serviceability and ultimate strength of concrete members. In recent years, several BSP field applications, for both building and bridges, have been reported in many countries. In addition, extensive experimental and theoretical investigations of the factors nfluencing the structural performance of epoxy bonded plated concrete beams have been reported by many researchers. This paper presents a review of the previous research on the structural behavior of composite steel plated concrete beams. An overview of the effectiveness of the bonded plate on the serviceability, strength and mode of failure of strengthened reinforced concrete beams is presented.