Simplified Solutions for Estimating the Lateral-Torsional Buckling Resistance of Nonprismatic Girders

Lateral-torsional buckling is a complex limit state that is often complicated by the presence of singly-symmetric and/or nonprismatic sections, which are common in composite construction. Estimating the buckling resistance of nonprismatic beams under uniform moment or moment gradients can be challenging. There are no general hand solutions readily available, and procedures for evaluating the buckling behavior of these relatively common cases are either absent from specifications or are overly simplified and have not been validated. This paper focuses on the development of a simplified weighted-average approach for approximating the buckling resistance of singly-symmetric and nonprismatic beams. A detailed parametric study including a wide range of parameters such as various intermediate bracing schemes and stepped flange transitions was conducted. The proposed design methodology was evaluated based on its ability to approximate the finite element solutions.

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