Cyclic testing of a metal building moment frame system with web-tapered members

Cyclic testing of a full-scale metal building with built-up, web-tapered members was carried out as part of an effort to develop a seismic design procedure for this type of moment frame system. The test building was designed as an Ordinary Moment Frame (OMF) with bolted end-plate moment connection. Test results showed that the system had a very high deformability; the elastic behavior was observed up to more than 2% story drift. But the ductility of the test frame was limited; the system failed at 2.6% story drift due to lateral–torsional buckling of the web-tapered members with a significant strength degradation. The testing also revealed that improper flange bracing with slotted bolt holes could jeopardize the resistance of the framing system with premature lateral–torsional buckling. The experimentally derived member forces and the associated failure mode correlated well with the code provisions for strength evaluation of web-tapered members. The lateral bracing force of the rafter reached 2.6% of the nominal yield strength of the flange.

► Cyclic testing of a metal building system with web-tapered members was conducted.
► Dominant failure mode of the test frame was lateral–torsional buckling.
► The system had very high deformability, but limited ductility.
► Lateral bracing force reached 2.6% of the nominal yield strength of the flange.
► Member strength and failure mode correlate well with the code provisions.