Rehabilitation in Simple Steel Connections against Progressive Collapse due to Column Removal

Strengthening of the structures against progressive collapse is very essential. Structural frames with simple connections are of highest potential in progressive collapse; therefore, rehabilitation of such structural system for both existing and new structures is vital. The available simple connections consist of double web angles and one seat angle which are assessed numerically, leading to the proposal of some effective techniques in order to reduce destruction due to this phenomenon. The proposed methods do not increase hardness and rigidity of the connections, and they hardly change the size or type of the loads of the other members, but, they are very beneficial in existing strategic structures. Eight models with both bolted and welded connections are considered in this study. The effect of damper in control of this phenomenon is assessed. The obtained results indicate that applying tendons in details improve performance of the models to considerable extent, because the proposed techniques reduce the vertical displacement of the connection up to 70%. Applying of damper in some of the models leads to a 20% reduction in vertical displacement.