A new methodology to design against disproportionate collapse is proposed for critical building that must be operational after a terrorist attack. The disproportionate collapse analysis uses the alternate path method where the structure must be designed to support the applied loads when a column is removed from the building. In some cases, when columns are close to each other, the blast pressure can damage more than one column. The new methodology can identify the number of columns or vertical load bearing components that should be removed in a disproportionate collapse analysis. Then, an alternate load path analysis is to be performed using the applied element method for the cases where one or more vertical load bearing components fail to match the actual risk level for critical structures and provide consistent design benchmarks. The applied element method is an optimized numerical technique which allows the analysis to be completed within a time-frame that is practical for design professionals. The method also allows the designer to choose the required resilience or the acceptable degree of risk based on the actual performance of the structure and the amount of acceptable damage under the effects of extreme loading events.
Elfouly, A., Khalil, A., Rahman, N. (2016). New Methodology of Designing for ATFP Using Modified Alternate Load Path Method, Structures Congress 2017. Key Words: ATFP, Nonlinear Dynamic Analysis, Progressive Collapse, Disproportionate Collapse, Alternate Load Path.