Experimental development and analysis of a high force/volume extrusion damper

Energy dissipation is critical to minimizing damage and degradation of structural connections due to earthquakes, wind loads or heavy traffic. Supplemental dampers are a means of repeatedly dissipating energy without damage to the structure. This research develops and analyses lead extrusion dampers as a potentially inexpensive method of providing this damping. However, widespread application in structural connections, requires small devices with a very high force to device volume ratio. A variety of prototype dampers were designed and tested to characterise their forcedisplacement behaviour and produce trade-off curves relating device geometry to force capacity. Results show that prestressing the working material is critical to obtain an approximately square hysteresis loop and maximum energy dissipation. Test results produced very different relationships than those reported for similar extrusion processes, indicating that yield stresses, rather than extrusion properties, dominate behaviour. Peak forces of 200-350kN were obtained for devices that were all able to fit within standard structural connections. The overall results indicate that repeatable, optimal energy dissipation can be obtained in a compact device to minimize damage to critical buildings and infrastructure.