US Patent 9027767 Rack shelving unit

A rack shelving unit includes front and rear beams, and one or more tie bars extending between the front and rear beams to form a shelf frame with the front and rear beams which can support a shelf. The tie bar can include flexible sidewalls that can flex laterally away from each other as the shelf is loaded to increase the compressive force of a compression retainer coupling the tie bar to the front and rear beams.