Practical formulas towards distortional buckling failure analysis for steel-concrete composite beams

• Published in: The structural design of tall and special buildings Vol. 25; no. 18; pp. 1055 - 1072
• Main Authors: Zhou, Wang-Bao, Li, Shu-Jin, Yan, Wang-Ji
• Format: Journal Article
• Language: English
• Published: Oxford Blackwell Publishing Ltd 25.12.2016; Wiley Subscription Services, Inc
• Subjects: Buckling; Coefficients; composite beam; Composite beams; Distortion; distortional buckling; elastic foundation beam method; Equivalence; Failure; Foundations; moment gradient; negative moment; Parameters
• ISSN: 1541-7794; 1541-7808
• DOI: 10.1002/tal.1297

Summary As the most predominant type of failure for steel–concrete composite beams (SCCBs) in negative moment area, distortional buckling is significantly impacted by the interaction effect between the applied loading and the torsional–lateral restraint stiffness of the bottom flange, which is termed as loading–restraint interaction here for short. Recently, a modified elastic foundation beam method capable of considering the interaction effect properly was proposed to calculate critical buckling moment for SCCBs under negative uniform moment. As a sequel to such development, a functional relationship between two dimensionless auxiliary parameters (i.e. equivalent slenderness ratio and equivalent moment coefficient) is discovered in this study. On the basis of the close association between the pair of dimensionless parameters, empirical formulas are derived in a remarkably simply explicit form to evaluate the critical buckling moment for SCCBs under negative uniform moment or moment gradient. These formulas are simple, user‐friendly and of practical use. Compared with conventional approaches without considering the loading–restraint interaction effect, the practical approach developed in this paper can achieve higher accuracy and is more easy‐implemented. The study lays a foundation for determining the ultimate bearing capacity of SCCBs considering moment gradient effect rapidly. Copyright © 2016 John Wiley & Sons, Ltd.