http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Wen-Fu Zhang,Leroy Gardner,M. Ahmer Wadee,Minghao Zhang 한국강구조학회 2018 International Journal of Steel Structures Vol.18 No.4
The Wagner coeffi cient is a key parameter used to describe the inelastic lateral-torsional buckling (LTB) behaviour of the I-beam, since even for a doubly-symmetric I-section with residual stress, it becomes a monosymmetric I-section due to the characteristics of the non-symmetrical distribution of plastic regions. However, so far no theoretical derivation on the energy equation and Wagner’s coeffi cient have been presented due to the limitation of Vlasov’s buckling theory. In order to simplify the nonlinear analysis and calculation, this paper presents a simplifi ed mechanical model and an analytical solution for doubly-symmetric I-beams under pure bending, in which residual stresses and yielding are taken into account. According to the plate-beam theory proposed by the lead author, the energy equation for the inelastic LTB of an I-beam is derived in detail, using only the Euler–Bernoulli beam model and the Kirchhoff -plate model. In this derivation, the concept of the instantaneous shear centre is used and its position can be determined naturally by the condition that the coeffi cient of the cross-term in the strain energy should be zero; formulae for both the critical moment and the corresponding critical beam length are proposed based upon the analytical buckling equation. An analytical formula of the Wagner coeffi cient is obtained and the validity of Wagner hypothesis is reconfi rmed. Finally, the accuracy of the analytical solution is verifi ed by a FEM solution based upon a bi-modulus model of I-beams. It is found that the critical moments given by the analytical solution almost is identical to those given by Trahair’s formulae, and hence the analytical solution can be used as a benchmark to verify the results obtained by other numerical algorithms for inelastic LTB behaviour.