科研之友
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摘要
Flexible giant crane boom is a statically indeterminate mixed structure equipped in giant boom cranes. It has a soaring complex geometry consisting of a giant combined boom and a flexible luffing structure, and the overall plastic instability is apt to happen under large hoisting, gravity and wind loads. As dually (geometrically and materially) nonlinear buckling analysis for flexible giant crane booms has not been well studied in literature, a detailed investigation is presented in this paper. Prior to carrying out a dually nonlinear buckling analysis, this paper first undertakes a geometric buckling analysis for a better understanding of the budding behavior. A method of applying temporary constraints is proposed to prevent the non-convergence issue caused by boom tilting. The incremental load method, the incremental displacement method, and the Newton-Raphson method are applied to evaluate the complete load-deflection response and the accurate critical load. Numerical analyses using the proposed method agree well with the conventional Arc-Length method and the survey results of a crane boom collapse accident. Results show that material nonlinearity is a remarkable factor that weakens the overall stability of the structure. The plastic development of the structure happens mainly in chord members of standard sections. The P - Delta effect of gravity load on the structure determines the first fracture position in the boom. The methodology developed in this paper can be easily extended for the development and applications of other performance-based approaches for enhancing the stability of flexible giant crane booms.
