Evaluation of the Stiffness and Time-dependent Clamping Characteristics of Disk Springs for Optimal Design of Friction Dampers

Friction damper is a seismic device that improves the seismic performance of a structure by incorporating multiple friction units with high-tension bolts and disc springs. The clamping force of high-tension bolts significantly influences the performance and quality of friction dampers. The purpose of this study is to validate the performance of disc springs applied to improve the clamping force and quality of friction dampers. The mechanical properties and time-dependent reduction in the clamping forces of the high-strength bolt with disc springs were evaluated in the performance tests of the disc springs. The loading test results show that the load resistance increases with an increase in the outer diameter and the loss of stiffness beyond a specific dimension (0.75h0). The bolt relaxation test results suggest that the reduction rate of the bolt clamping force after 31 days (744 h) was less than 4% for all specimens.