Three-Dimensional Slab Effects in Partially-Restrained Composite Connections

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9710238 Leon This project intends to develop experimental data and analytical tools to better characterize the three-dimensional effects and steel-concrete interaction in typical composite floor systems. Such as steel moment frames with composite floors for which very little is known about the ultimate strength capacity, ductility and toughness of these systems. From a fundamental standpoint research is needed to answer the following questions: o Behavior of exterior connections under cyclic load reversals. o Behavior of connections framing into the weak axis of columns when subjected to cyclic loads. o Interaction between lateral and gravity actions insofar as system strength and stiffness are concerned. o Effect of the floor slab on the torsional restraint at the end of composite beams. o Influence of the degree of shear connection on the strength and stiffness of the system under lateral loads. o Influence of the slab reinforcement detailing on the force transfer. o Behavior of shear studs under reversed cyclic loading. Experiments coupled with advanced analysis techniques will be used to address several of the topics described above. The experiments will include some unique bi-directional loading tests on a new type of partially-restrained composite (PR-CC) connections utilizing T-stubs and stiffened seats. Among the key items to be studies are the connections to the weak axis of the columns, connections at the edge of the floor slabs, and behavior of shear studs under reversed cyclic loads. The analytical component will develop new elements capable of efficiently modeling composite action under cyclic load reversals. Experimental data and simplified models based on the component method will be developed for T-stubs. These connection models, along with the elements developed to take into account composite action, will be used in parametric studies to define code-type design rules for structures with a wid e variety of PR-CC connections. ***