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01_General_Concepts.md

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    Renamed to EHRE
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    01_General_Concepts.md 2.74 KiB

    General concepts

    Exposure models describe the location and value of assets and people, as well as the connection to their fragility/vulnerability to specific hazards.

    The concept of "aggregated" exposure models arises in contrast with the idea of "building-by-building" exposure models: in the latter, each individual building is represented by its geometry and location, while in the former larger groups of buildings are represented by a single point in space, which is intended to represent a larger geographical extent.

    In order to run a damage calculation associated with a specific hazard, an exposure model needs to assign classes to the individual or grouped buildings, and these classes need to be meaningful in terms of representing the expected behaviour of the buildings when subject to the hazard. The latter means that the building classes need to allow the risk modeller to make a connection with fragility models that represent such behaviour.

    In order to run a loss calculation associated with a specific hazard, the exposure model also needs to assign replacement costs and/or number of occupants to each building (or building class) or group of buildings (or building classes). Similarly to the case of the damage calculation, the building classes need to be meaningful in terms of representing the expected behaviour of the buildings and outcome (in terms of losses) when subject to the hazard.

    The European High-Resolution Exposure (EHRE) model classifies buildings using the GEM Building Taxonomy v3.0 (Silva et al., 2022). The GEM Building Taxonomy v3.0 is a faceted taxonomy, which means that it characterises buildings by means of individual relevant attributes, such as construction material, type of lateral load-resisting system, number of storeys, expected ductility, etc. Building classes arise from the combination of the different possible values of these attributes. For example:

    • CR/LFINF+CDL/HBET:2-4 represents a 2- to 4-storey (HBET:2) reinforced concrete (CR) infilled frame (LFINF) with low seismic code design level (CDL),
    • MUR+CL/LWAL+CDN/H:1 represents a 1-storey (H:1) fired clay-unit (CL) unreinforced masonry (MUR) wall-system (LWAL) building with no seismic code design (CDN).

    It is not uncommon for aggregated exposure models to be associated with a specific occupancy case. Usual occupancy cases include residential, commercial and industrial buildings, for example. Other occupancy cases may be educational, agricultural or governmental buildings, as well as many others. The total number of buildings and distribution of building classes described above are thus associated with a specific occupancy case in the EHRE model (and, consequently, the ehre-core).