Seismic Characteristics of Concentrated Linked Beam Frame System

Abstract

Superior ductility and architectural versatility of moment resisting frames introduce them as a favorable candidate in high seismic regions. As they are not concentrated structural systems, they are hardly used in retrofitting old frames. Instead, braced spans or linked column frame systems are more efficient in strengthening. The concentrated linked beam frame system is used in this paper to strengthen a building frame without a lateral load resisting system. The link elements are added between the beams of two adjacent stories and are continuous through the building height but not connected to the foundation. The links are required for strength and drift control and are also the potential sources of energy dissipation. The prototype buildings of three, six, and nine stories are evaluated using linear and nonlinear analyses and the responses are compared with the concentrically braced and linked column frames. The results indicate that proper ductility is achieved with a smaller percentage of steel material. Evaluation of the proposed system with nonlinear dynamic analysis shows an acceptable response in the nonlinear range.