Energy response of a passive variable friction damper and numerical simulation on the control effects for high‐rise buildings

In this study, the behavior of a passive displacement‐dependent variable friction damper (VFD) was evaluated. The energy response behavior of a VFD specimen was investigated by conducting full‐scale dynamic loading tests. Full‐scale tests demonstrated that the VFD specimen produced a lower sliding force when the device response exceeded a predetermined displacement, resulting in a decreased dissipated energy ratio as the displacement increased. The VFD specimen exhibited stable energy response behavior as well as a stable friction sliding force and friction coefficient under sinusoidal, seismic response, and 100‐cycle loadings. The energy response of the VFD specimen was almost independent of the loading frequency. Moreover, a response simulation was conducted using a two‐dimensional 30‐story nonlinear mainframe model with brace‐type VFDs under various input motions, including observation records and long‐period, long‐duration waves. From the numerical simulations, the peak story drift in the case with brace‐type VFDs was not significantly greater than in the case with conventional friction dampers (FDs). The dissipated energy ratios of the mainframe and dampers in the case with the VFDs were approximately identical to those in the case with the FDs. In comparison with conventional FDs, VFDs can produce a lower peak story shear force and axial compressive force in the lowest‐story columns at the device installation span.