EPICentre Seminars - State-dependent fragility for ground motion sequences traditional vs innovative

18 November 2020, 12:00 pm–1:00 pm


This seminar will look at a framework to derive state-dependent fragility relationship of structures subjected to ground-motion sequences, such as mainshock-aftershock or triggered earthquakes.

This event is free.

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Arash Nassirpour – UCL EPICentre / Department of Civil, Environmental & Geomatic Engineering

A framework to derive state-dependent fragility relationship of structures subjected to ground-motion sequences (e.g. mainshock-aftershock or triggered earthquakes) is proposed. The hysteretic energy dissipated in the sequence is adopted as the main demand parameter, since it is a cumulative measure monotonically increasing with the length of the excitation. Based on theoretical considerations, the hysteretic energy-peak deformation trend is discussed, highlighting that:
1) the significant duration of the ground motion explains the variability of the hysteretic energy for a given peak deformation;
2) in the aftershock, a structure dissipates less energy (for a given aftershock peak displacement) if the peak displacement in the mainshock is higher. A vector-valued probabilistic seismic demand model consistent with these considerations is proposed in the form of a surface relating the hysteretic energy in the sequence to the peak deformation in the mainshock and a ground-motion intensity measure of the aftershock. 
The results show the feasibility of the proposed approach, effectively capturing damage accumulation without inconsistencies in the obtained statistical model. 


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Photo Credit: A local resident watches as rescue teams search for survivors in the debris of a collapsed building in Izmir, Turkey, Oct. 31, 2020. (AP Photo)

About the Speakers

Dr Roberto Gentile

Marie Curie Senior Research Fellow at EPICentre / UCL CEGE

I am a Marie Curie Senior Research Fellow at UCL (University College London). My main research interests focus on building frameworks for the design and analysis of earthquake risk reduction strategies. I am currently working at a multi-criteria decision making algorithm defining the optimal compromise among structural retrofit/strengthening, tax rebates from the government and insurance to reduce earthquake risk for individual reinforced concrete buildings or portfolios.

Karim Aljawhari

PhD Researcher at Istituto Universitario di Studi Superiori, Pavia