An Efficient Variable Friction Damper with a Curved Wedge

摘要

Passive friction dampers are known as effective devices improving structural response to earthquakes. They may be incorporated as a part of a base isolation system, or connected to braces in the building floors. It is known that the force magnitude in commercially available friction dampers is usually constant. The authors have shown in previous publications that additional improvement in structural seismic response can be obtained by using dampers with variable friction (incorporating a triangular wedge). This paper presents a study, performed on a new variable friction damper with a curved wedge. It is known that buildings with supplemental friction dampers not always return to the initial position after the earthquake, and remain in a deformed stage. The proposed device like that with a triangular wedge provides re-centring capacity. However, using a curved wedge element is aimed to change the friction force as a function of the wedge curvature and displacement, transferred to the damper, making it more efficient. The damper's mechanical properties and its hysteretic behavior are studied theoretically and verified experimentally using a small-scale model and a laboratory shaking table. A static scheme, enabling to get the force-displacement relationship of the damper for different wedge curvatures, was assumed. It is demonstrated that the experimentally obtained loading and unloading lines of the damper's hysteretic loops are non-linear and are similar to those predicted theoretically. The damper, proposed in this study, can be successfully used in structures designed for zones with high seismic activity.