Influence of steel shim hardness on the Sliding Hinge Joint performance

The Sliding Hinge Joint is a flexural connection designed for use at the ends of beams in steel moment resisting frames. It is an asymmetric friction connection, where energy is dissipated through sliding in slotted bolted connections in the beam bottom flange. The friction resistance and the repeatability of the hysteretic force displacement curves are dependent on the type of shim used. Brass or mild steel shims have been researched and used in construction to date. This paper describes tests on the sliding components conducted to investigate the use of steel shims of different hardness. The materials tested were mild steel, high strength quenched and tempered steel, and abrasion resistant steel. The beam and cleats which these shims slid against were Grade 300 mild steel. The specimens were tested dynamically at earthquake rates of loading. The abrasion resistant steel, the hardest material, produced the most stable and consistent sliding characteristics for all displacement cycles on different specimens. It also had the least material wear and the highest friction capacity per bolt. Compared to brass, high strength steels are more readily available, less costly, more easily erected, and less susceptible to corrosion, making them a preferred solution.

► Asymmetric friction connections tested dynamically with different shims.
► Shims were of different steel grade and hardness, sliding on mild steel.
► Performance was evaluated based on material wear and sliding characteristics.
► Abrasion resistant steel, the hardest shim tested, performed the best.
► Abrasion resistant steel had least wear, most stable and highest sliding friction.