Seismic performance of very short links in eccentrically braced substructures

Abstract

Research on the seismic performance of eccentrically braced hybrid frames indicates that utilizing very short links can enhance structural stiffness and load capacity. However, there is limited investigation into their effectiveness within eccentrically braced substructures featuring flush end plate bolted connections. This study involves an experimental and numerical investigation to understand the behavior of very short shear links with flush endplates bolted connections in the substructure. An experimental study of 8 specimens was carried out, and the variables studied included loading protocol, links length ratio, flange thickness, and end plate thickness. The experimental results showed that the co-design methodology for flush endplates and bolts of very short links exhibited acceptable performance. Very short shear links bolted with flush endplates demonstrated an average overstrength coefficient of about 1.8 and an ultimate plastic rotation angle above 0.12 rad. Numerical analysis explored the effects of length ratio, web height-to-thickness ratio, and flange width-to-thickness ratio on overstrength behaviors and yield capacity of very short links. The analysis indicated that the length ratio was crucial in determining overstrength coefficients and the yield capacity of very short links. The study established modified formulas that consider the impact of different variables to more accurately determine overstrength behaviors and yield capacity based on formulas in the Chinese code.