鋼管トラス柱の曲げねじれ座屈に及ぼす節点の溶接残留応力の影響

抄録

Residual stresses of tubular truss beam-columns which are introduced by assembling a truss by welding are estimated. Furthermore, the influence of the residual stresses on lateral-torsional buckling of the trusses is investigated. The residual stresses of the truss specimens are estimated by the cutting method. As a result, the chord members have large residual in-plane bending moments, but they have neither residual axial loads nor residual out-of-plane bending moments. In addition, chord sections around the truss joints have local residual stresses by welding. In the case of circular tubular trusses, out-of-plane bending stiffnesses of the chords are reduced early under axial compression, because the residual stresses of web walls of the chord sections are compression. The analytical lateral-torsional buckling loads of circular tubular truss beam-columns show the decrease of 6 or 8 %. On the other hand, in the case of rectangular tubular chords, the tube's self residual stresses are very large, and the residual stresses by truss assembling are relatively small. As a result, the residual stresses by truss assembling scarcely influence the buckling load of the rectangular tubular truss beam-column.