Rockfall quantitative risk assessment (QRA): Vulnerability of buildings subjected to rockfall impacts.

Risk analysis has two components: the hazard and the consequences. The former can be expressed by the impact probability of a rock block on an element and its intensity and the latter on the vulnerability of the exposed elements.

So far, the vulnerability has been mostly treated using empirical and/or judgmental approaches that do not provide objective and quantitative information on the expected damage and do not take into consideration the kinematical characteristics of the rock block impact. Besides, differentiation between different structural typologies is seldom made. These are limiting the application of these approached for damage prediction.

The research group of this project is working on structural vulnerability due to rockfalls since 2007 and has developed analytical methodologies for evaluating the vulnerability of reinforced concrete buildings impacted by rockfalls (Mavrouli & Corominas, 2010a y b). These approaches incorporate the kinematic properties of the block, their size and the probability of impact on key structural elements for the stability of a building. The obtained vulnerability is expressed in quantitative terms and can be directly integrated into the QRA using fragility curves (Corominas & Mavrouli, 2012).

In ROCKRISK we aim at developing a methodology to address the vulnerability of masonry buildings, which are typical structures in rural and mountainous areas. The methodology will take into consideration the rock block deceleration due to its impact on the exterior walls of a building (e.g. natural stone or brick walls), as it has been observed at rockfalls that occurred in built zones.

The achieved objectives of this area are:

- Definition of an analytical process for the evaluation of the damage for different masonry typologies, caused by blocks of different sizes and velocities and application to some characteristic typologies.

- Development of a methodology for the calculation of fragility curves that provide in a single diagram the probability of exceeding a given damage level for increasing rock block energy (depending on the block dimensions and velocity).

- Development of an Excel tool for the automatic calculation of fragility curves for a given study site depending on the local characteristics of the buildings and rock blocks (size and velocity) – see the Tools section of this web.

Other specific objectives in development are:

-  Recommendations for the design and reinforcement for reducing the vulnerability of the analysed structures.

-  Application of the QRA to a pilot case-study.

References:

Corominas J. & Mavrouli O. (2013) Estimation quantitative du risque (QRA) pour les bâtiments lié aux © European Union, 2002-2013 | http://europass.cedefop.europa.eu Page 4 / 7 éboulements rocheux: progrès et défis. Société Vaudoise des Sciences Naturelles (SVSN), Switzerland

Mavrouli O., Giannopoulos P. G., Carbonell J. M. and Syrmakezis C. (2017) Damage analysis of masonry structures subjected to rockfalls. Landslides. Volume 14, Issue 3, pp 891–904 doi: 10.1007/s10346-016-0765-8 Full Paper

Mavrouli O., Corominas J. (2010a) Rockfall vulnerability assessment for reinforced concrete buildings. Nat Hazards Earth Syst Sci 10:2055–2066

Mavrouli O., Corominas J. (2010b) Vulnerability of simple reinforced concrete buildings in front of the rockfall impact. Landslides 7(2):169–180