Simple connections retrofitted by dampers and bracket-tendon system against progressive collapse

ABSTRACT High potential for progressive collapse is one of the main weaknesses of structural frames with simple connections. Therefore, strengthening of this structural system is a necessity for both existing and new structures. In this study, the current simple connection with double web angles and one seat angle is modified by using dampers and a bracket-tendon system. The proposed methods of improvement increase the connection performance against progressive collapse due to column removal significantly, while they hardly change the stiffness and rigidity of the connections. Finite element software, ABAQUS, is used for this assessment. Vertical displacement of the modified connections after removal of the column is compared as an evaluation criterion. The results indicate that the bracket-tendon system is quite effective in reduction of vertical displacement of the connection up to 46%, and applying of dampers enhances the performance of the connections notably from 20% to 58%.