Browsing by Subject "Gravity framing system"
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Item Preliminary analysis and design of a test setup for evaluating lateral resistance of steel gravity framing systems(2020-06-25) Hernandez Carranza, Jorge Tercero; Clayton, Patricia M.The majority of steel structures in the U.S. follow a typical design practice. This practice consists of having relatively few frames of the building that resists lateral loads, and the remainder of the structure is designed to resist only gravity loads. The elements of this gravity system are connected using “simple shear” connections that are designed and assumed to behave as “perfect pins” that have no flexural strength or stiffness, thus generating no moment resistance at the connection. Nevertheless, past research has shown that the gravity system contributes to the lateral resistance of a building in non-negligible quantities. The main objective of this research is to perform preliminary analyses to support the design of a test specimen that will be used to evaluate the cyclic response of a multi-bay steel gravity framing test specimen subjected to lateral loads. This thesis explained and delineated the test program and concept that will be used in the large-scale system-level testing. Tests will be administered on variable-scale assemblies of two-by-three bays with dimensions of 16’x8’ and two half-stories of 6’. Three servo-controlled hydraulic actuators will be used to impose a displacement on the upper floor of the specimen. The first test specimen will evaluate the response with strong-axis decking metal deck (metal deck ribs oriented parallel to the load direction), and the presence and absence of seams at the column lines. Design and sizing of the specimen elements were done trying to have a continuation of previous research (Donahue, 2019) and based on the current practices in construction (Professional Advisory Committee). Several pushover analyses were done on SAP2000 (Computers and Structures, 2020), to a structural model of the test specimen, using several constructed moment-rotation spring models of hinges at the joints (to represent the simple shear connections). These moment-rotation spring models were developed and validated with the results of previous research (Donahue, 2019) and they accurately characterized the various detailing variations present in the previous studies. The results of these analyses showed the loads and displacements needed to “fail” the specimen, how each variation of the specimen could affect these loads and displacements, and the demands for designing critical elements like base beams, column support clevises, and the top truss diaphragm.