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Steel Sheet Sheathed Cold-Formed Steel Framed In-line Wall Systems. I: Impact of Structural Detailing
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Abstract Use of cold‐formed steel (CFS) framing as load‐bearing system for gravity and lateral loads in buildings is becoming increasingly common in the North American construction industry, notably in high seismic regions where light‐weight construction is an attractive option. Buildings framed with closely spaced and repetitively placed CFS members can be detailed to develop lateral resistance using a variety of sheathing options. A relatively new option involves the use of steel sheet as sheathing. Steel sheet sheathed CFS shear walls offer high lateral strength and stiffness, and provide ductility courtesy of tension field action within the steel sheet. Despite their acceptance, gaps in the understanding of their behavior do exist, notably, behavior under dynamic loading, the contribution of nonstructural architectural finishes, and the behavior of wall‐lines: shear walls placed inline with gravity walls. To this end, a two‐phased experimental effort was undertaken to advance understanding of the lateral response of CFS‐framed wall‐line systems. Specifically, a suite of wall‐lines, detailed for mid‐rise buildings, were evaluated through simulated seismic loading imposed via shake table and quasi‐static cyclic tests. Damage to the wall‐lines was largely manifested in the form of damage to fastener connections used for attaching the sheathing and gypsum panels, and separation of exterior finish layer. This paper documents and quantifies the progressively incurred physical damage observed in the tested wall‐line assemblies, and correlates it with the evolution of dynamic characteristics and hysteretic energy dissipated across a spectrum of performance levels.more » « less
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Microstructure refinement strategies in simulated carburized microstructures were evaluated because of their potential for improving the fatigue performance of case carburized components. Commercial 52100 steel was used to simulate the high carbon content in the case. Specimens were subjected to various thermal treatments in a quenching dilatometer. Reheating cycles to austenitizing temperatures were evaluated with respect to both prior austenite grain size (PAGS) and associated martensite and retained austenite (RA) refinement. Quantitative stereological measurements were performed to evaluate the micro-geometry of plate martensite and the size distribution of RA regions. Decreasing the reheating temperature resulted in finer PAGS, and multiple reheating cycles resulted in a more narrow PAGS distribution. Refinement in PAGS led to a reduction in martensite plate size and finer distribution of RA. Additionally, interrupted quenching below MS temperature was evaluated. This processing route results in a refinement of martensite plates and more stable RA. The stabilization of austenite may be mechanical or chemical in nature, owing to deformation of austenite during primary transformation, or due to partitioning of carbon into austenite similar to quenching and partitioning steels.more » « less
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1061/(ASCE)ST.1943-541X.0003433
