Design of friction damped structures using lateral force procedure

Abstract

A trilinear model is used to simulate the seismic resisting mechanism of a single-degree-of-freedom friction-damped system to reflect the situation in which both dampers and frame members lose their elastic resistance. The seismic response of the friction-damped system is normalized with respect to the response of its corresponding linear system by an approach that incorporates a credible equivalent linearization method, a damping reduction rule and the algebraic specification of the design spectrum. The resulting closed-form solutions obtained for the normalized response are then used to define a force modification factor for friction-damped systems. This force modification factor, together with the condensation procedure for multi-degree-of-freedom structures, enables the establishment of a quasi-static design procedure for friction-damped structures, which is intended for the benefit and use of structural practitioners. A curve-fitting technique is employed to develop an explicit expression for the force modification factor used with the proposed design procedure; it is shown that this simplification results in satisfactory accuracy. Finally, a design example is given to illustrate the validation of the proposed design procedure.