UT10, Steel Moment Resisting Frame with WUF-W Connections and Weak Panel Zone

Specimen UT10 was identical to Specimen UT08, except that it was subjected to column axial tensile loading. The specimen was applied increasing levels of column tensile loads and lateral cyclic loads at the top of the column simultaneously. The column axial loads of approximately 8 times the column lateral cyclic loads was force controlled and applied throughout the test. During the 6% story drift cycles, the maximum axial tension force of 1115 kips was applied to the column which is corresponding to 71% of specified minimum yield stress of the column.

Specimen UT10 was designed to model an interior joint of a steel moment resisting frame. The specimen consists of a single W12X106 A992 column with two W24X55 A992 beams attached to each flange. The subassemblage models a frame with approximately a 16 ft - 10 inches story height and a 29 ft - 8 inches beam span. The welded unreinforced flange-welded web (WUF-W) moment connection specimen was designed in accordance with Chapter 8 of the Prequalified Connections for Special and Intermediate Steel Moment Frames for Seismic Applications (AISC 358-10), while it has weak panel zone strength to promote severe inelastic deformation of the panel zone. The specimen was subjected to cyclic loads at the top of the column by applying increasing levels of the story drift angle. The pre-determined loading sequence followed the AISC Seismic load protocol.

To simulate points of inflection under lateral load, the ends of the members were pin connected. The bottom of the column was connected to a high capacity clevis and the top of the column was rigidly attached to the loading crosshead, which can be controlled to simulate a pin. Each beam end was supported by two actuators that are intended to serve as a roller support. That is, the actuators were controlled to keep the beam ends at a constant elevation, and allow free horizontal translation and rotation of the beam ends. Lateral support frames were provided near the beam ends and the beam-to-column connection region.