Catenary action in steel framed buildings with buckling restrained braces

• The frames with BRBs have more capacity than the bare steel frames.
• The building height has a negligible effect on the catenary action development.
• BRB placement scenarios have a significant effect on the catenary action development.

Progressive collapse is disproportionate failure of the structure due to the failure of a relatively small part of it. Catenary action is a load mechanism that is developed to resist the additional loads as a result of sudden column loss and prevent disproportionate collapse. Buckling restrained braces (BRBs) have been widely adopted as a dependable lateral load mechanism since the early 1990s. The impact of BRBs on the performance of steel frames subjected to lateral seismic forces suggests that BRBs might be beneficial to steel frames that are subjected to progressive collapse loads as well. The objective of this research is to conduct a detailed study on the impact of BRBs on the catenary action demands in steel framed structures. Push-down analysis of three, five and eight story steel frames with and without BRBs was carried out. The results showed that buckling restrained braced frames had a higher load carrying capacity compared to the bare steel frames. Different BRB placement scenarios and building heights were considered for this study. The BRB placement scenarios had more impact on the catenary action demands of the steel frame compared to the different building heights. Different loading types were studied and results showed that the loading of the model has significant impact on developed catenary forces. Finally, the results of the study highlight the importance of incorporating BRBs in future guidelines addressing the progressive collapse resistance of steel structures.