Asymmetric Friction Connection Bolt Lever Arm Effects on Hysteretic Behaviour

While Asymmetric Friction Connections (AFCs) have been employed as seismic energy dissipation devices in steel structures, development of design guidance based on robust understanding of their behaviour is required. This paper describes the quasi-static testing of 18 AFCs with Bisalloy 500 shims and 2 M16 Grade 8.8 bolts to quantify the effect of bolt lever arm to bolt diameter (l/d) ratio on the AFC sliding performance. Results show hysteresis loop shape remained similar for all l/d. However, increasing l/d from 1.38 to 3.88 reduced the average AFC strength by 42-47%, reduced the hysteresis loop loading stiffness by 33-47%; and reduced the effective friction coefficient from 0.28 to 0.08. For AFCs with l/d >= 3.25, bolts underwent significant flexural yielding, which reduced their performance in future cycles.

Automated summary

This study conducted quasi-static testing on Asymmetric Friction Connections and found that the ratio of bolt lever arm to bolt diameter has a significant impact on the sliding performance of AFCs. Increasing this ratio led to decreased strength and loading stiffness of AFCs, as well as a reduction in the effective friction coefficient.