Lap joints are used for angle steel members in truss towers for power transmission. Buckling strength with lap joints decreases because of the additional bending moment due to eccentricity, but the current design formula does not reflect that eccentricity as a parameter. In this paper, firstly, based on the Ježek’s theory, an evaluation formula for the inelastic buckling strength considering lap joints is shown. Secondly, the ultimate strength of members based on the current design formula is estimated and the structural safety of existing steel truss towers are revealed. Finally, a simple design formula is proposed.
