A multi-hazard risk prioritization framework for cultural heritage assets

Abstract

Abstract. Multi-hazard risk assessment of building portfolios is of primary importance in natural-hazard-prone areas, particularly for the prioritization of disaster risk reduction and resilience-enhancing strategies. In this context, cultural heritage assets require special consideration because of their high vulnerability to natural hazards – due to ageing and the type of constructions – and their strong links with communities from both an economic and a historical/sociocultural perspective. As part of the Cultural Heritage Resilience & Sustainability to multiple Hazards (CHeRiSH) project, funded by the UK Newton Fund, this paper introduces a multi-hazard risk prioritisation framework specifically developed for cultural heritage assets. The proposed framework relies on a multi-level rapid-visual-survey (RVS) form for the multi-hazard data collection and risk prioritization of case-study assets. Because of the multi-level architecture of the proposed RVS form, based on three levels of refinement/information, an increasing degree of accuracy can be achieved in the estimation of structural vulnerability and, ultimately structural risk of the considered assets. At the lowest level of refinement, the collected data are used for the computation of seismic and wind risk prioritization indices, specifically calibrated in this study for cultural heritage assets with various structural/non-structural features. The resulting indices are then combined into a unique multi-hazard risk prioritization index in which the intangible value of cultural heritage assets is also considered. This is achieved by defining a score expressing the cultural significance of the asset. The analytic hierarchy process is extensively used throughout the study to reduce the subjectivity involved in the framework, thus obtaining a simplified, yet robust, approach which can be adapted to different building typologies. The proposed framework is applied to 25 heritage buildings in Iloilo City, Philippines, for which innovative, non-invasive techniques and tools for improved surveying have also been tested. Thermal and omnidirectional cameras have helped in the collection of structural data, together with drones for the inspection of roofs. Results of the study are presented and critically discussed, highlighting advantages and drawbacks of the use of new technologies in this field.

Typhoon Fragility Analysis and Climate Change Impact Assessment of Filipino Cultural Heritage Asset Roofs

“…The procedure proposed in this study has been developed within the Cultural Heritage Resilience & Sustainability to multiple Hazards (CHeRiSH) project [7], funded by the UK Newton Fund. This project aims to develop a multi-level risk and resilience assessment framework for CH assets in the Philippines exposed to multiple natural hazards.…”

“…The twenty-five CH assets analysed in this study ( Figure 1) have been surveyed during a field trip in Iloilo City, Philippines, in July 2019 by a research group composed of members from the University College London (UCL, United Kingdom), the De La Salle University (DLSU, Philippines) and Central Philippines University (CPU, Philippines) [7]. The surveyed CH portfolio is composed of 24 RC structures and one URM building date back to the first half of the 20th century.…”

“…Corrosion phenomena, which can affect the strength of both fasteners and LWMS, must then be considered in the typhoon-risk quantification both at building specific and portfolio level. As shown in Figure 2, most of the surveyed CH roofs were characterised by diffused and heterogeneous corrosion levels [7].…”

“…Since no damage-to-loss models are specifically available for Filipino buildings, those developed by the Federal Emergency Management Agency (FEMA, 2014) [22] in terms of direct repair cost for residential buildings in the USA are used in this study. This assumption is somehow justified by the fact that the prescriptions included in the Filipino building codes [19] are fully consistent with the recommendations of US building codes [7], across the years. Moreover, the damage-to-loss curves reported in Figure 3 are defined in terms of percentage of building replacement value rather than in absolute terms.…”

“…Typhoon-related economic losses in the Philippines are not just due to the adverse environmental conditions. Rapid population growth along the coast together with highly-vulnerable structures/infrastructure contribute to intensify the typhoon-risk of Filipino buildings [7]. Particularly vulnerable in this sense are CH asset roofs (i.e., wood frame and light-weight metal sheet, LWMS) because of the general lack of any hazard-resistant design considerations, presence of non-engineered structures/detailing, and material/structural degradation due to aging.…”