Experimental and Analytical Investigation of Optimized Cold-Formed Steel Compression Members

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Title: Experimental and Analytical Investigation of Optimized Cold-Formed Steel Compression Members
Author: Klingshirn, Daniel J
Advisors: Dr. Nabil A. Rahman, Committee Co-Chair
Dr. Emmett Sumner, Committee Chair
Dr. James Nau, Committee Member
Abstract: In recent years, load-bearing light steel framing (LSF) systems have become popular in the low to mid-rise construction market in the United States. This construction market covers a wide range of building usage, including apartment and office buildings, hotels, and schools. In the past, standard C-shaped metal studs have been the only option for designers and contractors when selecting a cross section for load bearing studs. An alternative cross section, which has primarily been used as a roof purlin in Europe and is seldom found in the U.S., is the sigma-shaped section. Recognizing the potential of this section for use within a LSF system, a research program was completed at North Carolina State University’s Constructed Facilities Laboratory (CFL) to evaluate the axial compression capacity for the proprietary stud product SigmaStud®. The experimental test program, which includes fifty-eight sigma-shaped stud tests and forty-eight comparable C-stud tests, was developed with the ultimate goal of adding the SigmaStud® to the pre-qualified column set of the relatively new Direct Strength Method (DSM) design method. Studs were tested at various lengths to force global, distortional, and local buckling failure modes. Additionally, the test program contained studs with and without web holes. Comparisons of experimental results with the AISI design methods, Effective Width (EWM) and Direct Strength (DSM), are discussed. Based on the results of this research program, the SigmaStud® section is recommended to be added to the pre-qualified member set of the DSM. Both design methods are shown to produce accurate strength predictions. Another important conclusion from this test program is that the optimized sigma-shaped stud is shown to be a much more efficient use of material than a comparable C-stud. Strength increases ranged from 30-175% for 24†studs and 45-450% for 120†studs. Web holes were shown to decrease stud capacity in most cases, although strength increases were observed in both short and long studs. Additionally, long studs are shown to be very sensitive to loading eccentricity, while short studs are not.
Date: 2009-12-02
Degree: MS
Discipline: Civil Engineering
URI: http://www.lib.ncsu.edu/resolver/1840.16/2119

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