Jordan Journal of Civil Engineering

Improving the seismic performance of the knee braces of moment frames


Mehran Majidi; Majid Yaghoobi;


Structural design methods should provide the ability to sustain large numbers of load cycles and capability of absorbing energy for the structures. By installing the reduced knee brace in moment resisting frames, the large amount of energy can be absorbed due to the plastic deformations of the brace, prior to the formation of plastic hinges in the main members. Herein, the brace is bolted to the beam and column. Hence, the damaged brace can be easily replaced after loading. By using ABAQUS software, the angle between the brace and beam which maximizes the capability of the energy absorption is specified. Also, findings prove that the aforesaid angle maximizes the stiffness and strength of the brace. Additionally, with the help of six specimens, the effect of brace length on the seismic performance of this brace is assessed. According to the obtained results, increasing the length of the brace improves the seismic parameters. With regard to architectural limitations, the most suitable length should be selected. These investigations are conducted in large and small span frames. Findings show that usage of the reduced knee brace in large span frames can absorb more energy.


Reduced knee brace, Energy absorption, Stiffness, Ultimate strength