Shake-Table Testing of a Steel Building with Seismic Collectors: Collector Responses and Design Recommendations

A series of shake-table tests were performed on a half-scale two-story steel building with seismic collectors in a composite floor and an unfilled metal deck roof using the large high-performance outdoor shake table (LHPOST) at UC San Diego. The test objectives are to investigate the load paths and seismic responses for the collectors. This paper presents detailed test results focusing on the seismic response of the collectors and the collector-to-column connections. The adequacy of the conventional design approaches is evaluated based on the test responses. Test results show that the collectors were subjected to not only seismic-induced axial forces but also seismic-induced bending moments, highlighting that the common practice of neglecting seismic moment demands in collectors may be overly simplistic. Additionally, test results indicated that the conventional analysis tends to overestimate the collector axial force demands, whereas incorporating the effect of gravity column shear adjacent to the collectors improves accuracy. Furthermore, the tests highlight that unintended bending in composite collectors can significantly increase axial force demands at the steel portion of the composite collector connections, suggesting that current design practices, which ignore composite action, may be unconservative. A general design procedure for composite collector connections is proposed to address this.