Use of friction dampers in the seismic design and retrofit of buildings

In the last decade, many energy dissipating systems have been proposed to raise the seismic design and retrofit of structures beyond the conventional ductility design approach. Among these new systems, friction damping has shown some great potential. In a friction damped system, friction damping devices are inserted in a structure and slip at a predetermined optimum slip load during severe seismic excitations, before any yielding of the structural members has occurred. Slipping of the devices allows the structure to dissipate the input seismic energy mechanically by friction rather than by inelastic deformation of the structural elements. This paper presents an overview of the recent research conducted in the area of friction damping at the University of British Columbia. Analytical and shake table test results are first summarized to illustrate the superior earthquake performance of friction damped structures compared to the performance of conventional building systems. The development of a design slip load spectrum for the rapid evaluation of the optimum slip load distribution is then presented. The availability of this design slip load spectrum simplifies the design procedure for framed structures equipped with friction devices and should lead to a greater acceptance by the engineering profession of friction damping as an innovative and viable earthquake resistant design method. The dampers can be used in new construction or can be inserted in existing buildings for retrofit purposes.