Seismic behavior of rack structures

In order to allow the owner to change the layout according to need, rack structures must be easy to assemble; therefore, the connecting elements must reflect this need. This paper presents experimental findings for a typical rack connection, tested under static and cyclic loads. The beam-to-column connection studied utilizes hooks fabricated with the beam; the hooks are to be inserted in special slots at the columns, in such a way that they can be easily disconnected when a new corridor or free space is required. The moment-rotation curves obtained show a continuous hardening enabling the connections to reach about half of the beam plastic moment. The failure mode is initiated with yielding of the outermost hooks in a progressive sequence towards the beam neutral axis. Non-linear analyses of the rack structure under different seismic conditions were performed, considering the measured moment-rotation curves. The non-linear calculated displacements were more than twice the displacements predicted with the classical linear analysis.