Physical vulnerability assessment procedures for confined and unconfined (unreinforced) clay brick masonry buildings due to mass movements, rigid foundation

Abstract

While climate change and urban development in mountainous terrain continue to impact society through geo-mass transport phenomena, quantitative risk models must evolve and be communicated as clearly as possible to enhance the social appropriation of knowledge. Recent advancements in mass movement risk analysis equate external hazard intensity measures with the internal strength of buildings. However, procedures for estimating building capacity and developing fragility curves remain less well-defined, particularly for masonry buildings, which are among the most common construction types worldwide, especially in less developed regions, and where laboratory or field data may be scarce. Fragility curves relate hazard intensity to the probability of reaching or exceeding a level of physical damage and have thus become essential tools in vulnerability and risk assessments related to natural hazards. This paper presents a procedure for deriving structural damage thresholds through fragility curves for mass movements, featuring the following characteristics: it is not based on seismic design parameters, does not require excessive computational resources, and is straightforward to implement. Recognizing that damage during a mass movement event may depend not only on the structural strength of buildings —assuming a rigid foundation— but also on ground resistance, which can cause permanent deformations, this study focuses on the rigid, fixed foundation scenario. The method incorporates geometrical and mechanical parameters along with their associated uncertainties, and provides damage state thresholds as functions of momentum flux and mass movement height for two typical wall types: unconfined, unreinforced clay brick masonry (URM) and confined clay brick masonry (CM).