PERFORMANCE-BASED PLASTIC DESIGN METHOD OF HIGH-RISE STEEL FRAMES

Under major earthquakes,high-rise steel moment frames designed to the current codes will undergo inelastic deformations in an uncontrolled manner. According to the principle of work-energy conservation,this paper presents a performance-based plastic design (PBPD) method for the design of high-rise steel frames. The method uses pre-selected target drift and yield mechanisms as key performance indicators. The design base shear for a selected hazard level is calculated by equating the work needed to push the structure monotonically up to the target drift to that required by an equivalent single degree of freedom to achieve the same state. Plastic design is performed to detail the frame members and connections in order to achieve the targeted yield mechanism and behavior. The method has been successfully applied to a ten-storey steel moment resisting frame,and validated by inelastic dynamic analyses and pushover analysis. In the cases,the frames develop desired strong column sway mechanisms,and the story drifts are well within the target values,thus meeting the desired performance objectives. The addressed method herein can form a basis for the performance-based plastic design of high-rise steel frames.