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Structural robustness

Modern design codes recommend ensuring an appropriate level of robustness to prevent from disproportionate collapse under an exceptional event. One of the major difficulties is to quantify the concept of structural robustness when checking the structural safety under exceptional situations. In this respect, the Eurocodes define the structural robustness as “the ability of a structure to withstand events like fire, explosions, impact or the consequences of human error, without being damaged to an extent disproportionate to the original cause”. To meet such requirements, robustness indicators are essential to assess the capacity of the structure to withstand events, estimate the safety against disproportionate collapse, and finally be used as a decision support for design choices. Several robustness metrics have been recently proposed in the literature. However, despite developments in this field, these methods are still not fully used in engineering practice to effectively assess structural robustness.

The main objective of these research activities is to propose an approach to quantify the structural robustness. Progressive collapse is modelled based on an iterative coupling between the yield design approach and a non-linear analysis.

Illustration of the proposed approach

Static load considered

First iteration of yield design calculation

Non linear analysis

Second iteration of yield design calculation

Final configuration

Some indices are then introduced to measure the structural robustness and be used as a decision support tool.

 

Robustness Propagation Failure Index (RFPI)

Robustness Energy Index (REI)

References

El Hajj Diab, M.  2019. ANALYSE DE LA ROBUSTESSE STRUCTURALE - Caractérisation des actions accidentelles et/ou exceptionnelles et de leurs effets sur les structures. Thèse de l'Université Paris-Est. Soutenue le 24 octobre 2019.

El Hajj Diab, M., Orcesi, A., Desprez, C., Bleyer, J., 2019. An embedded yield design approach within anon-linear analysis for structural modeling of progressive collapse. Presented at the RILEM spring convention and sustainable materials, systems and structures conference, Rovinj, Croatia.

El Hajj Diab, M., Orcesi, A., Desprez, C., Bleyer, J., 2019. A scenario-based procedure for structural robustness assessment. Presented at the IABSE symposium 2019 Guimarães, towards a resilient built environment - risk and asset management, Guimãraes, Portugal.