Special Truss Moment Frame Component Test 3 - 2C12x20.7

Special truss moment frame component test 3, made of double channels 2-C12x20.7, was tested under cyclic loading. The test setup is a representative of half of the chord in the special segment of the prototype special truss moment frame. Due to insufficient restraint at loading point in the previous test, a much larger capacity bracing at loading point was used in this test. To reduce bulging of the web, stitches were moved closer to the plastic hinge region and two pairs of web stiffeners were implemented. While a 1/8 in. gap between the west channel and the gusset plate started at 1% story drift, bulging of the web was not apparent until 1.5% story drift was reached where a crack at the end of the weld was also observed. The bottom stitch closest to the plastic hinge separated from the channels at 2% story drift which resulted in larger bulge of the web. The test was terminated at 2.75% story drift or 8.69% member drift due to fracture in the flange of the channel as well as the complete separation between the first 2 pairs of stitches and the channels.