Experimental study on behavior of steel double-channel built-up chords of special staggered truss steel frame structure under cyclic loads

In order to study the seismic behavior of the special segment when the chords of special staggered truss steel frame structure use double-channel built-up members, quasi-static tests on eight full-scale double-channel built-up members under reversed cyclic bending were conducted. The main parameters were stitch spacing, lateral support settings and stiffener settings. Experimental results indicate that the reduction of stitch spacing can reduce out-of-plane slenderness ratio of the individual channel, preventing lateral-torsional buckling of the individual channel, thus can make sure that the two channels work together. The lateral support adjacent to the plastic hinge region is very effective in restricting out-of-plane deformation of channels at the plastic hinge region, and preventing the lateral-torsional buckling of the member, thus can improve energy dissipation capacity of the member. Stiffeners which are located at the plastic hinge region can fully eliminate local buckling of plates, and the member yields and dissipates energy instead of buckling, thus leads to some increases in energy dissipation capacity and rotation capacity of members. The study enriches the achievements on the seismic behavior of special staggered truss steel frame structure, and also offers reference for other engineering applications of double-channel built-up members. © 2017, Editorial Office of Journal of Building Structures. All right reserved.