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Structural Engineering and Mechanics
  Volume 49, Number 2, January25 2014, pages 273-283
DOI: http://dx.doi.org/10.12989/sem.2014.49.2.273
 


Elastic flexural and torsional buckling behavior of pre-twisted bar under axial load
Chang Hong Chen, Yao Yao and Ying Huang

 
Abstract
    According to deformation features of pre-twisted bar, its elastic bending and torsion buckling equation is developed in the paper. The equation indicates that the bending buckling deformations in two main bending directions are coupled with each other, bending and twist buckling deformations are coupled with each other as well. However, for pre-twisted bar with dual-axis symmetry cross-section, bending buckling deformations are independent to the twist buckling deformation. The research indicates that the elastic torsion buckling load is not related to the pre-twisted angle, and equals to the torsion buckling load of the straight bar. Finite element analysis to pre-twisted bar with different pre-twisted angle is performed , the prediction shows that the assumption of a plane elastic bending buckling deformation curve proposed in previous literature (Shadnam and Abbasnia 2002) may not be accurate, and the curve deviates more from a plane with increasing of the pre-twisting angle. Finally, the parameters analysis is carried out to obtain the relationships between elastic bending buckling critical capacity, the effect of different pre-twisted angles and bending rigidity ratios are studied. The numerical results show that the existence of the pre-twisted angle leads to \"resistance\" effect of the stronger axis on buckling deformation, and enhances the elastic bending buckling critical capacity. It is noted that the \"resistance\" is getting stronger and the elastic buckling capacity is higher as the cross section bending rigidity ratio increases.
 
Key Words
    pre-twisted bar; flexural buckling; torsional buckling; coupling; finite element
 
Address
Chang Hong Chen and Yao Yao: School of Mechanics and Civil Engineering, Northwestern Polytechnical University, Xi\'an 710072, China
Ying Huang: School of Civil Engineering, Xi\'an University of Architecture and Technology, Xi\'an 710055, China
 

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