STMF 1.2 - Cyclic Loading Test of Special Truss Moment Frame with Double-Channel Chord Members and Multiple Vierendeel Panel Special Segment

After STMF 1.1 was tested, the special segment was cut out and STMF 1.2 which had 3 Vierendeel panels made of 2 intermediate vertical members (2C6 x 13) in the special segment was spliced to the remaining elastic part of STMF 1.1. Splice locations are at 0.43 and 0.22 times the panel length from the end of the special segment for the top and bottom chords, respectively. The clear spacing between the first pair of stitches and the gusset plate shows that the vertical intermediate member was welded at 19 in. The aspect ratio of each panel in the special segment is 0.82, which is within the AISC 341-10 limit.

In comparison, STMF 1.2 exhibited higher elastic stiffness and strength than STMF 1.1 due to the addition of intermediate vertical members. The first yield of the specimen was approximately at 0.5% story drift. During the 2nd cycle of 1.5% story drift, its strength started to drop slightly due to fractures around the plastic hinges of intermediate vertical members. By 2% story drift, the strength of STMF 1.2 drastically dropped and the hysteretic response began to resemble that of STMF 1.1. until the end of the test at 4% due to complete failure of the intermediate vertical members. The proposed detailing configuration was able to prevent LTB in the plastic hinge zone.