Preventing progressive collapse through strengthening beam-to-column connection, Part 1: Theoretical analysis

This is part one of a two-part paper reporting the results of an investigation into the characteristics of catenary action and their effect on structures. In this paper, it is shown that when catenary action occurs, the bending moment will decrease significantly in the beams. It is also demonstrated that when a column is destroyed by a blast, the failure strain will be reached at the simple beam-to-column joint. To enhance the survival capability of the steel framed structures subjected to a terrorist blast, novel retrofitting schemes are proposed in this paper for strengthening the simple joints of existing tall steel framed structures by changing the partial-strength shear-resisting joints to the full-strength moment-resisting joints, ensuring the full development of catenary action. To support the above mentioned viewpoints, the catenary behavior of a truss model is evaluated and exact results are given. In the subsequent companion paper, these views are also corroborated by means of finite element analysis.