Date of Award
Civil and Environmental Engineering
Madugula, M. K. S.,
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The objective of the investigation is to determine theoretically the effective length factors of cross-braced solid round diagonals in all-welded steel communication towers. Three beam-column models with different boundary conditions (pinned, elastically restrained, and fixed) were investigated and it was shown that a beam-column with elastic restraints at ends and at cross-brace location is the most accurate. However, for design purposes, when the ratio of the diameter of the leg to the diameter of the diagonal exceeds three, beam-column model with fixed ends and elastic restraint at cross-brace location is satisfactory. The theoretical results were compared with results of tests on 26 specimens. Based on small deflections and elastic behavior, theoretical equations were developed for symmetric and anti-symmetric deflection modes. It was shown that during initial stages of loading, symmetric deflection mode will dominate while anti-symmetric deflection mode will dominate at failure and ultimately, the failure is in anti-symmetric mode. The theoretical results were again compared with tests carried out on 26 specimens. Finally, finite element analysis was carried out on one tower for the following six cases: (a) elastic stage with symmetric initial deflection, (b) elastic stage with anti-symmetric initial deflection, (c) elastic stage with superposition of symmetric and anti-symmetric initial deflection, (d) elastic-plastic stage with symmetric initial deflection, (e) elastic-plastic stage with anti-symmetric initial deflection, and (f) elastic-plastic stage with superposition of symmetric and anti-symmetric initial deflection. The effect of the magnitude of anti-symmetric deflection was studied for three towers. The finite-element analysis also confirmed that failure would be in the anti-symmetric mode. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis2000 .C35. Source: Masters Abstracts International, Volume: 39-02, page: 0547. Adviser: M. K. S. Madugula. Thesis (M.A.Sc.)--University of Windsor (Canada), 2000.
Chen, Zonghua., "Theoretical effective length factors for cross-braced solid round diagonals." (2000). Electronic Theses and Dissertations. 4367.