This paper describes a large research project which was conducted to develop experimental data on composite structural elements consisting of a steel-concrete- steel (S-C-S) sandwich using headed studs to transfer shear within the composite element. This form of construction may be used as an alternative to either stained steel plate construction or reinforced concrete construction. The principal focus of the work was on marine structures such as arctic offshore drilling structures, tidal barrages, floating structures and submerged tube tunnels. Three distinct categories of structural elements were evaluated: cylinders, flat panels and curved panek’junctions. A total of 59 tests were conducted on large structural elements. The tests included composite cylinders under static axial, static radial and impact loads, flat panels under static in-plane axial, static out-of-plane bending fatigue out-of-plane bend, and static in-plane shear loads, and curved and junction panels under combined axial and bending loads. A 1: 10 scale was chosen for the cylinder tests and a 1:4 scale was used for all other flat and curved panels. To aid researchers and designers doing work on similar types of elements, descriptions of the test specimens, method of specimen preparation and test procedures are given in the paper. The experimental results will be available for release in 1998.

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.

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.

Diagonal Mar Centro Comercial is a 350,000 square meter (3.75 million square foot) mixed use commercial development in Barcelona, Spain. It is located at the terminus of the premier boulevard in Barcelona, avenida Diagonal and will be known as Diagonal Mar - the avenue by the sea. The project is located only two hundred meters from the shores of the Mediterranean Sea and approximately ten kilometers east of the Olympic Village - home to the athletes in the 1992 Olympic Games. A commercial venture of Diagonal Mar S.A., the first phase consists of a 165,000 square meter (1.75 million square feet) retail mall and hypermarket (the largest in Spain) and six levels of underground parking for 5,100 automobiles in 185,000 square meters (2.0 million square feet) of space. Construction cost for Phase I is estimated to be $180,000,000 US dollars. Residential housing and office buildings are planned for later phases of the project. The site is a very large triangular plot bounded by the extension of avenida Diagonal on the northwest, avenida Josep Pla on the west and avenida Taulat on the south. The sides of the triangle are approximately 333 meters (1,072 feet) along avenida Diagonal, 285 meters (935 feet) along avenida Taulat and 236 meters (774 feet) along avenida Joseph Pla. The 24 meter (79 feet) deep excavation required for the underground parking, located 18 meters (59 feet) below the shallow water table, will create the largest basement substructure in the world and will remove more than 1 .O million cubic meters (1 .3 million cubic yards). The sheer size of the project and its location so close to the sea posed a whole host of enormous engineering challenges for the design and construction planning team as follows: (1) Excavation retention method; (2) Foundation system selection and design; (3) Excavation/substructure construction method and sequence, (4) Substructure system selection and design.

Adequate performance of coupled walls depends on sufficient stiffness, strength, and energy dissipation of coupling beams. To meet these goals, reinforced concrete coupling beams are often deep On the other hand, shallower steel beams can be used instead, and steel/composite coupling beams may be designed as shear-yielding members which have a more desirable energy dissipation characteristics. Such an option is not feasible for reinforced concrete beams. Well-established guidelines for links in eccentrically braced frames can be extrapolated to steel coupling beams. However, these provisions ignore the effects of concrete encasement which often surround the steel coupling beam. The reported research was conducted in an effort to till this void. Four one-third scale subassemblages of a wall segment and a coupling beam were extracted from a prototype structure, and were tested. The main test variables were the presence or lack of concrete encasement, and the number of web stiffeners. The encasement around the steel coupling beam increased the beam stiffness by 25%, and the shear strength by 18%. The additional stiffness enhances the level of coupling action which could lead into significantly larger wall axial loads, and would increase the demands on the foundation system. The increased stiffness needs to be incorporated in design. Although all the specimens could develop and exceed the expected capacities, the specimens failed due to less than desirable performance of the connection. Participation of the connection region towards energy dissipation became more substantial for the encased specimens, which is not desirable in view of post-earthquake repair. Connection design has to account for the increased capacity due to encasement, and details need to be improved to delay connection failure until plastic hinges in the coupling beam are fully mobilized. The encased specimens without any stiffeners performed as well as the specimens with stiffeners equal to or less than those required for steel link beams. No significant differences between the strength and stiffness characteristics of the encased specimens could be found. The experimental data suggest that nominal encasement is an effective means for preventing web buckling, and stiffeners are not needed. Current design codes need to be reevaluated for the cases where the steel coupling beam is encased.