Earthquake-resistant steel frames with energy dissipating knee elements

Abstract

Moment-resisting and concentrically braced frames have been widely used for earthquake-resistant steel buildings. However, neither of these structural systems alone, can efficiently provide the required stiffness and ductility simultaneously, which are required for structures subjected to severe seismic excitations. This paper presents the results of an investigation into a new alternative structural system for earthquake-resistant steel buildings, which aims to overcome the limitations of existing systems. This system employs a diagonal brace with one end anchored to a knee element. Stiffness is derived from the nonbuckling brace, while ductility under severe lateral loading is achieved through flexural yielding of the knee element. Large-scale model tests were conducted to assess the performance of this system. A nonlinear analytical model of the knee element has been presented for application in the dynamic analysis of the new structural system. Using this analytical model, the dynamic response of a multistorey frame with energy dissipating knee elements is compared with the corresponding eccentric braced frames. © 1995.