LTB analysis of pre-stressed mono-symmetric thin-walled beams with deviators under non-uniform bending moments using a simplified FEM

Abstract

A FE formulation has been newly presented for the lateral-torsional buckling (LTB) analysis of an externally pre-stressed (PS) steel beam, possessing deviators under non-uniform bending moments. Firstly, the total potential energies of the PS mono-symmetric thin-walled beams in possession of un-bonded/bonded deviators are derived depending on the number of deviators. Afterwards, the in-plane solutions of the PS mono-symmetric simple/cantilever beams under the lateral load can be analytically derived through the use of discontinuous functions. A simplified FE procedure is then developed based on the total potential energy, taking into consideration the effects of double tendons. Finally, the critical buckling loads of simple and cantilever PS mono-symmetric beams which were subjected to the non-uniform moments with the increasing of deviators are evaluated using the FEM and Rayleigh-Ritz method. As a result, the FE solutions were found to be very well matched to solutions by Ritz method and Abaqus. Additionally, the effects of double tendons, eccentricity, and the initial tension on LTB of the PS beam system were investigated with the increase of un-bonded/bonded deviators.