The use of reinforced concrete or composite core walls and steel gravity or moment frames offers an economical alternative to RC wall/core and concrete frame systems. Successful performance of these systems depends on the adequate performance of walls/cores, steel frames, and frame-core connections. Fundamental issues related to cyclic performance of composite walls/cores have yet to be addressed. A coordinated research program, combining experimental and analytical studies is formulated to investigate the performance of composite wall - hybrid systems. The primary objectives of this project are to: (1) conduct and document experimental studies of composite walls, (2) investigate force transfer mechanisms between concrete and encased steel sections under cyclic tension and compression, (3) evaluate the experimental results with respect to wall strength stiffness, and ductility, (4) assess existing code requirements and (5) provide essential data so that complete building systems can be investigated analytically to assess the economics of using hybrid/composite systems. Five approximately 1/3-scale composite walls and approximately ten, large-scale isolated boundary columns will be tested. A prototype structure will be used to derive general parameters of the test specimens and to relate experimental data to overall structural response. In addition, cyclic load tests of isolated boundary columns will be done to provide detailed data on force transfer mechanisms and confinement requirements. General analytical studies of specimen behavior will be performed to evaluate the ability of simplified code equations to predict the strength and stiffness of the composite walls. Modeling techniques appropriate for analytical studies of complete structural systems will also be investigated. This is an award under the 2nd year Initiative (NSF 94-154) on `Composite and Hybrid Structures.`
