Torsional buckling

Since pultruded profiles have low shear stiffness, shear deformations must be taken into account. Additionally, second-order effects like lateral-torsional buckling have to be considered carefully. 

Lennon, R.F. and Das, P.K. (2000) Torsional buckling behaviour of stiffened cylinders under combined loading. Thin-Walled Structures, 38, 229-245. 

Chan Yue, Thamwattana Ngamta, Hill James, M. (2011). Axial Buckling of Multi-Walled Carbon Nanotubes and Nanopeapods. Eur. J. Mech. A/Solid, 30, 794-806. Silvestre Nuno. (2012). On the Accuracy of Shell Models for Torsional Buckling of Carbon Nanotubes. Eur. J. Mech. A/Solid, 32, 103-108. 

Mb,or Lateral torsional buckling resistance moment of member... 

P(7) The resistance of the member shall be adequate to prevent lateral torsional buckling. 

Compression flange buckling Lateral torsional buckling Partial coefficients ULS SLS... 

Calculate the maximum distance between lateral bracing, lb, to resist lateral torsional buckling. 

Mottram, J.T. Lateral-torsional buckling of a pultruded I-beam, Composites,... 

To minimise the cost of the beam, a pultruded GFRP box profile, available off the shelf , is chosen. Thin-walled box sections are very efficient for beams and have a high resistance to lateral torsional buckling. 

Tests to characterise the flexural, torsional, buckling and collapse responses of pultruded GFRP structural grade profiles... 

CUR96 (2003), Recommendation 96 Fibre-Reinforced Polymers in Civil Load-bearing Structures, CUR commission C124, CUR, Gouda, The Netherlands (in Dutch). Davalos J F, Qiao P and Salim H A (1997), Hexural-torsional buckling of pultruded fiber reinforced plastic composite I-beams, Composites Structures, Vol. 38, Nos. 1-4, pp. 241-250. 

Shan L Y and Qiao P Z (2005), Flexural-torsional buckling of fiber-reinforced plastic composite open channel beams. Composite Structures, Vol. 68, No. 2, pp. 211-224. 

Stoddard W P (1997), Lateral-torsional buckling behaviour of polymer composite I-shaped members, PhD thesis, Georgia institute of Technology, Atlanta, GA. 

The column web thickness-to-depth ratio, tcw/Tc influences the column flange rotation. The column web stiffness, when an idealization of the column cross section is made, as shown in Fig. 4, is proportional to the ratio, (tcw) /Tc. The greater the column web stiffness, the greater the torsional resistance provided to restrain column flange rotation, 6c, and beam lateral-torsional buckling. In the case of the W14 x 283... 

Since it is fully restrained in lateral direction it will not be affected by lateral torsional buckling. 

It can be observed that the lateral buckling behaviors agree well with solutions in the existing literatures. It can therefore concluded that the stability problem formulation and finite element modelling method proposed in this paper are capable of making accurate predictions of the elastic flexural- torsional buckling loads of web-tapered doubly symmetric and monosymmetric I-beams incorporating the shear deformations. 

Asgarian, B., Soltani, M. Mohri, K, 2013. Lateral-torsional buckling of tapered thin-walled beams with arbitrary cross-sections. Thin-Walled Structures, 62, 96-108. 

Kala, Z. 2013. Elastic lateral-torsional buckling of simply supported hot-rolled steel I-beams with random imperfections. Procedia Engineering 57 504-514. doi 10.1016/j.proeng.2013.04.065. 

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