| Summary: | 博士 === 國立成功大學 === 土木工程學系碩博士班 === 100 === Based on the fracture mechanics, this study took stress intensity factor (SIF) as the index to measure the stress concentration of a crack tip, and analyzed the crack problems for some common welded connections in steel structures, including fillet welded cruciform connections, fillet welded lap connections, and beam-column connections, by using the Least-Squares Method along with finite-element method or optical experiments. In the numerical part of this study, numerous numerical examples were analyzed to investigate the influences of the important geometric dimensional parameters to SIF, and the numerical results were employed to develop the regression formulas for KI or KII for these common welded connections. In the experimental part of this study, a total of twenty-one welded connection specimens were tested and analyzed using the Digital Image Correlation Method. After compared with the numerical results from the finite-element simulations and the Least-Squares Method and with the results computed from the formulas in literature, the test results showed that the employed experimental method could give the satisfactory SIF evaluations for the welded connection specimens. Moreover, the test results also verified the precision of the employed numerical analysis method. The derived SIF regression formulas and the employed optical experimental method in this study could be applied to the safety assessments of existing steel structures.
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