Experimental study on lateral-torsional buckling of truss beam-columns with rectangular tube chords

Rigidly-jointed truss beam-columns which are composed of rectangular tube chords have the high strength of the lateral-torsional buckling, and can be more easily fabricated than trusses composed of circular tube chords. However, the web members may cause local deformations in the flat plate elements of rectangular tube chords around the connections, which might reduce the buckling strength. Therefore, the economical and safe design requires the accurate evaluation of the buckling strength, taking both advantageous and disadvantageous effect mentioned above into consideration. In the case of trusses with circular tube chords, experimental and theoretical work have been carried out by many researchers. On the other hand, there are few experimental researches on the trusses with rectangular tube chords. From this point of view, an experimental and theoretical investigation on the truss beam-columns which chords are rectangular tubes and web members rectangular or circular tubes have been carried out. The paper presents that the buckling strength of the truss beam-columns increase due to the restraining effect of web members and a tensile chord, and discusses that the reduction of the buckling strength due to the effect of local deformation around the connections cannot be disregarded in the design