Abstract
The Alternate Load Path (ALP) is a useful method that has generated a considerable recent research interest for the assessment of progressive collapse. The outcome of the ALP analysis can be assessed either using the force-based approach or the energy-based approach. The Unified Facilities Criteria (UFC- 4- 023-03) of progressive collapse guideline - have outlined that the force-based approach can either be analysed using static or dynamic analysis. The force-based approach using static analysis is preferable as it does not require a high level of skill and experience to operate the software plus no effort is required in scrutinising the validity of the analysis results output. However, utilising the static approach will eliminate the inertial effect in capturing the actual dynamic response of the collapsed structure. In recent years, the development of the energy-based progressive collapse assessment is attracting widespread interest from researchers in the field; as the approach can produce a similar structural response with the force-based dynamic analysis by only using static analysis. Most of the current energy-based progressive collapse assessments are developed following the requirements which are given in the progressive collapse guidelines provided by the Unified Facilities Criteria. However, little attention is given to the development of the energy-based approach using the Eurocode standards as a base guideline. This article highlights the merits of utilising the energy-based approach against the force-based approach for a collapsed structure and explains the collapse mechanism of a steel frame in the perspective of the energy concept. The state of the art of energy-based progressive collapse assessment for a structural steel frame is reviewed. The comprehensive review will include insights on the development of the energy-based method, assumptions, limitations, acceptance criterion and its applicability with the European standards. Finally, potential research gaps are discussed herein.
Highlights
General Services Administration (GSA) document defined progressive collapse as “an extent of damage or failure that is disproportionate to the magnitude of the initiating event” [1]
The phenomenon of progressive collapse can be divided into three stages; the local failure, the spread of damage, and the final collapse state
The energy-based Alternate Load Path (ALP) method is the best substitute to the force-based ALP method in bringing forth an efficient and reliable progressive collapse assessment
Summary
General Services Administration (GSA) document defined progressive collapse as “an extent of damage or failure that is disproportionate to the magnitude of the initiating event” [1]. More detail is given on the TF method instead of the other two methods When it comes to realism, the ALP method is the best method to evaluate progressive collapse potential because it can imitate the real structural response towards localised failure. For that reason, this method is favoured by researchers in understanding the concept of progressive collapse. This method is favoured by researchers in understanding the concept of progressive collapse In this method, a load-bearing element is notionally or instantaneously removed to initiate a response, but the event that caused the removal the loadbearing element is not considered [1, 6]. The structural response is compared with the predefined acceptance criteria to justify the vulnerability of the building against progressive collapse
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