Rotational Friction Damper in Diagonal Bracing

In this paper a new friction damper, which can be installed in X-shape bracing, is introduced. This device is in the group of displacement-dependent devices and consists of several steel plate and friction pads. These frictional pads are bonded between steel plates at the predefined special regions. In order to apply normal clamping force on the device, 9 high strength bolts are used. The applied clamping force can be adjusted by tightening of these bolts. In order to keep the clamping forces constant, several spring disc washers are used.This damper was manufactured at Earthquake Engineering Laboratory of Urmia University and installed inside a model SDOF steel frame. The frame was put over the shaking table and its responses under several earthquake excitations were recorded. For checking the effectiveness of the device in mitigation of the responses of a four storey frame, several nonlinear time history analyses were conducted. The results of the experimental tests and the analytical calculations show that this modified friction damper not only provides an added structural stiffness, but also has good seismic energy dissipation capability.