Seismic loss estimation for efficient decision making

Proceedings of the 8th International Conference on Computational Methods in Structural Dynamics and Earthquake Engineering (COMPDYN 2015), 2021

In this paper, a framework developed for the seismic risk assessment and loss estimate of the Health-Care sector is described. The methodology herein presented derived from a wider study that refers to a multi-hazard (earthquake, hurricane, flood, landslide, rockfall, avalanche) and multi-asset (healthcare and energy infrastructure). The loss estimate is based on the probabilistic modelling of hazards and asset vulnerability and an overall assessment of the impact generated from the suffered damage treated as a deterministic consequence of it. Specifically, the total impact computation is based on the combined analysis of different aspects, such as physical damages, service reduction, and social impact. For the sake of completeness also the impact is evaluated per each aftermath level. It must be pointed out that in so doing the loss computed per each impact can be ensured as hazard independent. An important role in the impact evaluation is also played by resilience. A simplified evaluation of preparedness and resourcefulness at asset and local level is performed to originate a set of resilience-based coefficients which, in turn, are used to influence the evaluation of the loss per each impact component and level of damage. Finally, the Expected Annual Loss (EAL) is provided as the exponential relation between the probability of damage occurrence expressed as mean annual frequency, and the loss, expressed in economic terms. So, this relation can define the properties of damage occurrence and loss of each possible event. Thanks to the quantitative approach of the framework it can be seen how each risk aspect influence the curve properties, such as the horizontal stretch due to resilience influence on the loss degree and the vertical stretch due to vulnerability effect on the damage occurrence.

Interest in sustainability and resilience of buildings has led to a growing body of literature on merging environmental impact assessment methods with seismic loss estimation methods. Researchers have taken different approaches to connecting the two fields with the common goal of estimating the social, environmental, and economic impacts of damage to buildings subject to seismic events and thus enabling the study of tradeoffs between performance objectives. The differences among these studies include topics such as treatment of uncertainty , types of components and systems considered in the performance assessment, fidelity of structural analysis ranging from region-specific empirical fragility curves to detailed building-specific finite element analysis, scope of life cycle assessment, and so on. One of the aspects of the most diverse treatment has been in obtaining environmental impact data and relating it to pre-use impact estimates. For example, the translation of damage and repairs into life-cycle environmental impacts has been done by one of three approaches: (1) Economic Input-Output Life Cycle Assessment (EIO-LCA) has been applied to economic loss estimates; (2) repair cost-ratios have been applied to environmental impacts from the pre-use stage; and (3) repair descriptions have been used to model environmental impacts of damage scenarios directly using process life cycle assessment (LCA). All of the approaches are generally accepted but may pose limitations in certain applications and can potentially result in inconsistent conclusions from study to study. A review of existing literature in the area is presented and is followed by a comparative analysis and discussion of the outcomes of taking different environmental life cycle assessment approaches. This paper provides a comprehensive overview of the research efforts in this area and discusses opportunities for further development in order to make the implementation consistent and practical for design decision making.

Structure and Infrastructure Engineering, 2020

This paper presents a uniform and consistent semi-quantitative classification of consequences of failure of buildings as part of a multi-level seismic risk management framework for existing buildings to help building owners make risk-informed decisions for the seismic evaluation and retrofit of existing buildings to minimise the life safety risk. The management framework consists of three levels of risk assessment, namely: (i) Level 1: Preliminary seismic screening; (ii) Level 2: Semi-quantitative seismic risk screening; and (iii) Level 3: Quantitative seismic evaluation. The proposed classification consists in general of three classes, namely: (i) Consequence Class-Low (CC-L), (ii) Consequence Class-Medium (CC-M); and (iii) Consequence Class-High (CC-H). These consequence classes are based on semi-quantitative criteria, including building occupancy, number of people at risk, building area, number of storeys, and mobility and ability to escape. The proposed classification can be used to refine the building importance classification in many codes, standards and guides to yield more uniform classification of consequences of failure that can be integrated with the seismic risk management framework to determine more uniform risks of failure. An example illustrating the application of the proposed classification is provided for the case of office buildings.

Engineering Structures, 2017

The probabilistic seismic risk assessment in terms of economic losses for building portfolios aims to the estimation of the probability distribution functions (PDF) of economic losses for a set of stochastic events representing the seismic hazard at a particular geographic zone. This paper proposes a methodological approach to evaluate and integrate, in a consistent and rigorous way, the economic losses as a function of the seismic hazard intensity for prototype building constructions. Prototype building models are designed and characterized with a set of reference parameters. By means of 3D structural models, detailed nonlinear response history analyses are performed for a set of seismic records at several increasing intensities. Seismic records are selected to represent particular seismological and geotechnical conditions at the site of analysis. Then, a component-based model is conformed considering structural, non-structural, and content components potentially susceptible to damage. Each component type is assigned a fragility specification for various damage states in terms of costs and times of repair. Using Monte Carlo simulations, the different sources of uncertainty are included in the assessment of the costs and times of repair at different seismic intensities. Uncertainties in the hazard, model response, damage states, and costs and times of repair are considered. Aspects such as geographical variations in the hazard, scale economy, special commercial conditions, minimum or total intervention costs, and business interruption costs are included in the assessment. Finally, the results are represented by means of vulnerability functions for specific building typologies. To illustrate the methodology, a case study is presented in detail for a typical 5-story reinforced concrete moment resisting frame building designed for special seismic code level and located in a typical soft soil deposit of Bogotá, Colombia. Additional results are presented for six (6) different building typologies illustrating variations in results due to different story heights and seismic code levels. The resulting vulnerability functions are compared with equivalent results from other similar methodologies. Conclusions and possible potential applications related to probabilistic risk assessment are summarized.

RILEM Bookseries, 2021

Buildings are among the major contributors to environmental impacts, in terms of non-renewable resource depletion, energy and material consumption, and greenhouse gas (GHG) emissions. For this reason, modern societies are pushing towards the refurbishment of existing buildings aiming at the reduction of their operational energy consumption and at a major use of renewable energy and lowcarbon materials. At the same time, buildings are expected to provide population with safe living and working conditions, even when hit by different kinds of hazards during their service life, such as earthquakes. Until recently, life cycle assessment (LCA) procedures tended not to include the effects of natural hazards. However, if considered in a building LCA, earthquake-induced environmental impacts would constitute a very informative performance metric to decision-makers, in addition to the more customarily used monetary losses or downtime indicators. Within this context, therefore, a comprehensive review of the existing literature is presented, with comparisons between available methodologies being carried out in terms of their employed seismic loss estimation method, environmental impact assessment procedure, damage-to-impact conversion, impact-to-cost conversion, and selected decision variable. Further, an illustrative case-study application is also included.

Bulletin of Earthquake Engineering

The definition of relationships between damage and losses is a crucial aspect for the prediction of seismic effects and the development of reliable models to define risk maps, loss scenarios and mitigation strategies. The paper focuses on the analysis of post-earthquake empirical data to define relationships between buildings’ damage expressed as usability rating or as global damage state and the associated costs for repair (i.e. direct costs) or for population assistance (i.e. a part of total indirect costs). The analysis refers to the data collected on residential buildings damaged by 2009 L'Aquila earthquake. For different usability rating or damage states, the paper presents the costs expressed in terms of percentage with respect to the reference unit cost of a new building (%Cr and %Ca for repair and population assistance costs, respectively). In particular, the costs analysis refers to undamaged, lightly or severely damaged buildings classified according to usability ratin...

Within seismic loss estimation much research has been carried-out in regards to characterizing ground motions, but less in regards to building vulnerability (also known as fragility) and damage costs. There is especially little data in respect to earthquake damage costs. Reasons for this include the fact that major earthquakes are infrequent and do not always occur in the urban environment or affect the range of building types of interest. Furthermore, the usability of cost data in the latter case is often limited by the lack of detail in the associated cost data or by its unavailability. To circumvent this problem cost ratios (ratio of damage level to total construction replacement cost) are commonly used. However, the methodology for deriving cost ratios is often unsatisfactory given that supporting evidence of their applicability for diverse geographical areas and building types is not usually provided. New data and a new approach to cost ratio definition are presented in this pa...

2022

Industrial facilities play a significant role in economic growth now and for the foreseeable future. However, past earthquake reconnaissance surveys have revealed that the seismic vulnerability of these facilities has resulted in huge economic losses mainly due to operational failures. As per ASCE 7, industrial facilities could be classified as buildinglike and nonbuilding-like types. In this paper, the fragility of building-like industrial facilities is focused. First, relevant design code requirements and provisions were summarized for further discussion on possible improvements. This is followed by a review of the latest techniques, challenges, and knowledge gaps related to the fragility development of building-like industrial facilities. The review indicates gaps in fragility development specific to seismic loss quantification. The need for updated design guidelines, component interdependencies, robust seismic modeling, and analysis techniques for improved decision-making are hence recommended.

New procedures are being developed in the United States for building-specific seismic performance (loss) assessment. These procedures are substantially different from those currently used in practice. The new procedures will characterize performance in terms of direct economic loss, indirect economic loss and casualties rather than by building component deformations and accelerations. Uncertainty and randomness will be captured in every step of the performance assessment process. The paper summarizes the state-of-practice in seismic performance assessment, discusses the types of performance assessment made possible by the next-generation procedures, describes each step in the proposed loss assessment process and introduces a performance assessment calculation tool that can be used to perform the loss calculations.

2016

The probabilistic seismic risk assessment in terms of economic losses for building portfolios requires the seismic hazard assessment, the definition and characterization of the building portfolio and the estimation of the expected economic losses of specific building typologies for increasing seismic intensities. The probability distribution function of economic losses for different seismic intensities can be estimated by integration of individual building component ́s repair costs. By means of Monte Carlo simulations, all relevant variables that influences the final repair cost can be introduced into the analysis. The results of the analysis are integrated and represented through specific vulnerability functions for each building typology, which relates the expected economic losses and its corresponding uncertainty measure with the seismic intensity level. The integration of losses considers the uncertainties associated with the hazard assessment, the dynamic response of the model,...