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Author ORCID Identifier

0000-0003-3895-6932

AccessType

Open Access Dissertation

Document Type

dissertation

Degree Name

Doctor of Philosophy (PhD)

Degree Program

Civil Engineering

Year Degree Awarded

2022

Month Degree Awarded

September

First Advisor

Kara D. Peterman

Second Advisor

Sergio F. Breña

Third Advisor

Meghan Huber

Subject Categories

Civil Engineering | Structural Engineering

Abstract

Cold-formed steel (CFS) framed buildings and subsystems have demonstrated safe and reliable performance while under lateral and seismic loads. Combined with their structural efficiency, this makes CFS-framed buildings popular choice even in high seismic zones. However, due to the complexity in response of CFS members and their interaction in subsystem and system levels, more research needs to be conducted to better understand the overstrength in the system, as well as the contribution of non-structural components to the overall response of the building. The lateral force resisting system (LFRS) of CFS framed buildings consist primarily of shear walls and diaphragms. The current AISI S400 North American Standard for Seismic Design of CFS framed systems includes only the design of shear walls and diaphragms sheathed with structural wood panels (AISI 2015). In this design document in combination with provisions in ASCE 7-22, the design of shear walls is limited to seismic demand loads up to a 6-story building. The larger CFS-NHERI effort, of which this work is a part, seeks to expand this to 10 stories. The CFS-NHERI project culminates in a 10-story test on the shake table at UCSD UHPOST. To isolate diaphragm behavior, which can be convoluted in a full-scale building test. The UMass effort examines the performance of diaphragms under lateral load, sheathed with novel sheathings. The best performing of these specimens will be tested also on the shake table, planned for 2023. A total of eight 10 ft by 15 ft CFS diaphragm specimens with variable sheathing on two CFS framing systems were tested following the cantilever test method. For this, a test rig was designed, fabricated, and installed in the structural laboratory to allow in-plane loading of diaphragms. The framing systems are comprised of 54 mils floor joist spaced by 2 ft and 97 mils joist spaced by 4 ft. Specimen sheathings included Oriented Strand Boards (OSB), steel deck, and a new dual structural skin system: structural Fiber Cement Boards (FCB) fastened to steel deck. Specimens were tested under monotonic and cyclic loading. The cyclic loading protocol was adopted from FEMA 461 (FEMA 2007). Results of this work provide a unique characterization of the lateral response of a CFS diaphragm sheathed with the dual skin system in which its behavior and strength are unknown, as well as a detailed progression of failure and failure mechanism in the diaphragms sheathed with form deck. Ultimately, a comparison with current design methods and design recommendations are provided.

DOI

https://doi.org/10.7275/31023083

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