Development of Bidirectional Cyclic Lateral Loading Protocols for Experimental Testing of Steel Wide-Flange Columns

Steel columns in frame buildings subjected to earthquake shaking undergo bidirectional lateral drift demands. Till now, the majority of past experimental and numerical studies were primarily concerned with the unidirectional column behavior. This paper proposes a procedure to develop representative bidirectional lateral drift histories for experimental testing of steel columns in moment-resisting frames (MRFs). To this end, a 3-dimensional numerical model of a prototype four-story building with perimeter MRFs is analyzed using a suite of ordinary ground-motion records. The first-story drift orbit is idealized in the form of elliptical drift cycles. Statistical data of parameters defining these elliptical drift cycles is collected. The data serves for the development of bidirectional symmetric loading protocols representative of design-basis earthquakes. The developed protocol is adopted in a testing program that assessed in full-scale the influence of bidirectional cyclic loading on steel columns.