| The main objectives of this dissertation are: to study the actual strength and failure modes of outrigger beam-wall connections under constant shear and cyclic tensile forces; to develop a basic understanding of force transfer mechanisms in such connections; to investigate the influence of floor diaphragms on the performance and stiffness characteristics of such connections; and to develop design criteria for ductile failure modes. To achieve these objectives, a coordinated experimental and analytical study was performed. The research involved a 15-story prototype structure with a central core and steel perimeter frame. The floor diaphragm was assumed to be rigid in the design model. The experimental study was conducted in two phases: (1) seven specimens were tested, and a design model was developed based on the measured responses of the five specimens that failed due to stud pullout. Because of the wall boundary element around its connection, one of the remaining specimens failed due to weld fracture. A new design methodology was used for the last specimen. This design methodology allowed the input energy in the connection to dissipate through the yielding and eventual fracture of the shear tab, rather than the pullout of headed studs.; In phase two, two large-scale wall specimens were tested to verify the design model developed in phase one. Each wall had two outrigger beam-wall connections: one located in the expected plastic hinge region, and the other located in the region where moderate cracking was expected. Each wall was tested in two steps. First, the walls and their connections were simultaneously loaded: one wall to the drift ratio of 2.5%, and the other to the drift ratio of 0.5%. Then, each connection was tested separately until failure.; In the analytical phase, the flexibility of the floor diaphragm was evaluated in two steps: (1) parametric studies were conducted by an analysis package to examine the number of floors and floor nodes in flexible diaphragms; (2) a mathematical model was developed to verify the results of step one. This mathematical model was a conservative technique to identify the minimum number of floors required for a diaphragm to be rigid. |
