Retrofit of simple welded connections against progressive collapse

Abstract

The progressive collapse potential of simple welded connections was investigated analytically. The performance of the connections was evaluated based on the requirement of UFC-4-023-03. The simple connection, which consists of a seat angle, was defined as the base model, and eight other models were derived from the base model to represent further effective details. Several solutions were developed to retrofit this kind of connection against progressive collapse in the event of removal of a column. The results showed that utilising a tendon in the connection caused considerable improvement: the proposed techniques reduced the vertical displacement of the connection by up to 50% due to the catenary action of the tendon, leading to resistance against load of the removed column. Highly effective methods that improve the quality of results even further with only a small effort are also proposed. The focus of this work was on methods that do not increase the rigidity of the connection, in order for them to be applicable in existing important structures.