Experiments on link-to-column connections in steel eccentrically braced frames

Abstract

This thesis describes the results of an experimental project on the seismic performance of link-to-column connections in steel eccentrically braced frames (EBFs). Previous research in this area has highlighted the very large force and deformation demands on link-to-column connections and the difficulty in identifying economical and practical details that can provide satisfactory performance. Therefore, the main objective of this experimental project, which has built upon recent work in this area by others, was to conduct pilot tests on two proposed link-to-column connection details to evaluate their potential to satisfy the connection performance requirements of the 2005 AISC Seismic Provisions. A total of eight specimens were tested in this program. In the first link-to column connection detail, the link was welded to the face of the column using either double-sided fillet welds, or a combination of PJP groove welds and fillet welds. This detail is envisioned to be most appropriate as a shop welded link-to-column connection. The second detail was constructed with reinforcement, in the form of two supplemental stiffeners in the first panel of the link adjacent to the column. This detail is expected to be suitable for field welding, and was developed in a joint study with Hong and Uang (2005, 2006) at the University of California at San Diego (UCSD). The results from both the experimental program and the analytical studies conducted at UCSD identified these two link-to-column connections as very promising details. Both details showed the potential for outstanding performance, with the capability of developing the link's full plastic rotation capacity without connection failure, and the capability of satisfying the link-to column connection performance requirements of the 2005 AISC Seismic Provisions. Despite the fact that only a small number of tests were conducted in this pilot program, the excellent performance of the connections in these tests justifies further work on these details. Additional analytical and large-scale experimental studies are recommended to further confirm the performance of these connections, identify appropriate limits of application for these details, and to further refine the preliminary design approaches that have been developed for these connections.