| Summary: | 碩士 === 國立中興大學 === 土木工程學系 === 91 === ABSTRACT
No other field in the study of strength of materials has such a varied history as the theory of buckling strength of compression members in metal structures. The column theory derived from Euler’s formula in 1744. However Euler’s theory pertained only to situations where compressive stress below the elastic limit. In order to solve the disagreement between test results and Euler’s formula in the case of inelastic buckling, Engesser then presented his tangent-modulus theory in 1889. It was not until 1947 that Shanley explained the real column behavior and provided an improved concept which finally leads to a just appreciation of Engesser’s original tangent-modulus theory.
The medium long column is mainly controlled by residual stress based on the research in Lehigh University. Since 1960, structural steel design according to the AISC Allowable Stress Design Specifications had used the SSRC parabolic equation based on the one proposed by Bleich. Moreover, in the development of the LRFD Specification, the AISC Specification Committee decided to continue using only one column strength curve for steel design based on Bjorhovde’s research and the LRFD column formulas are thus obtained.
The calculation process of critical stress for each buckling mode is tedious especially for singly symmetric or asymmetric sections. The computerized method provided in this research is more effective than repeating the routine procedures by hand. Furthermore, the calculated values based on the LRFD formulas are compared with the tabulated values given by LRFD Specification and it is found in this reseach that they do not always match to each other.
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