Hysteretic Behaviour of Asymmetrical Friction Connections Using Brake Pads of D3923

Asymmetrical Friction Connections (AFCs) can provide stable hysteretic behaviour to dissipate seismic energy. However, the metallic sliding surfaces used in such AFCs may develop metal to metal corrosion compromising performance and their frictional resistance may be low. Non-metallic sliding surfaces should therefore be considered. The quasi-static testing performance of 12 AFCs using bonded non-asbestos D3923 brake pads on the sliding surfaces is evaluated. Three configurations of brake pads bonded on the sliding surfaces of the cap and fixed plates were considered: i) brake pads bonded over the full sliding surfaces (A), ii) strips of brake pads bonded beside the bolt holes (B), and iii) full recessed brake pad with strips beside the bolt holes (C). The greatest AFC strength occurred in the initial sliding cycles, and became constant after the brake pad reached a steady wear state, at which time the hysteresis loop became symmetric, stable, and predictable. For the A, B, and C brake pad configurations, the steady wear state effective friction coefficient varied between 0.12-0.17, 0.10-0.14, and 0.12-0.17, respectively, with the average values being 0.15, 0.12, and 0.15. The peak values, obtained in the initial sliding cycles were 1.7, 2.2, and 1.9 times these average values, while the lower bound values, obtained after many sliding cycles were 0.71, 0.71, and 0.70 times these average values. The recessed brake pad Configuration C is the preferred configuration since it had the highest steady wear state friction coefficient and the least degradation.