EARTHQUAKE-RESISTANT STEEL FRAMES WITH ENERGY DISSIPATING KNEE ELEMENTS

Moment-resisting and concentrically braced frames have been widely use d for earthquake-resistant steel buildings. However, neither of these structural systems alone, can efficiently provide the required stiffne ss and ductility simultaneously, which are required for structures sub jected to severe seismic excitations. This paper presents the results of an investigation into a new alternative structural system for earth quake-resistant steel buildings, which aims to overcome the limitation s of existing systems. This system employs a diagonal brace with one e nd anchored to a knee element. Stiffness is derived from the nonbuckli ng brace, while ductility under severe lateral loading is achieved thr ough flexural yielding of the knee element. Large-scale model tests we re conducted to assess the performance of this system. A nonlinear ana lytical model of the knee element has been presented for application i n the dynamic analysis of the new structural system. Using this analyt ical model, the dynamic response of a multistorey frame with energy di ssipating knee elements is compared with the corresponding eccentric b raced frames.