Static Security Analysis based on Vulnerability Index (VI) and Network Contribution Factor (NCF) Method

Risk assessment and management is an important step towards resilient and sustainable cities. Among many other perils, both natural and manmade, seismic risk is a major threat for resilience and sustainability. In recent decades, several methods for seismic risk assessment have been proposed, including the well-known Vulnerability Index Method (VIM). In this study, a probabilistic version of the VIM, which we call the Vulnerability Index Method-Probabilistic (VIM_P), is proposed. The VIM_P requires essential information on the seismic hazard and on the vulnerability of the building stock. Seismic hazard is determined using the exceedance rates of macroseismic intensities, as defined in the European Macroseismic Scale (EMS). Seismic vulnerability is defined by means of vulnerability probability density functions (pdf) that describe the probability distribution of the corresponding vulnerability index. Beta-like functions are used for these pdfs. VIM_P quantifies seismic vulnerability by means of three vulnerability curves, Lower, Best and Upper, according to the quantity and quality of available information, thus allowing three estimates of seismic vulnerability and risk. Then, seismic risk is computed via the convolution of seismic hazard and seismic vulnerability, considering semi-empirical damage functions. Seismic risk is given through the exceedance frequencies of the damage grades. To highlight the capabilities of the VIM_P, the seismic risk of about 70,000 residential buildings in Barcelona was assessed. According to the results, the exceedance frequency of the collapse damage state for more than the 50% of the buildings in the Eixample district would be greater than 1 × 10−5. This confirms the relatively high seismic risk in the city, mainly due to the high vulnerability of the built environment. Specific software, USERISK20015, has been developed for routine applications of VIM_P. It is hoped that VIM_P and this new tool for seismic risk assessment will be useful to stakeholders and civil protection authorities for risk management and prioritizing actions that can help to create more resilient, sustainable cities.

Al Hoceima is one of the most seismic active regions in north of Morocco. It is demonstrated by the large seismic episodes reported in seismic catalogs and research studies. However, seismic risk is relatively high due to vulnerable buildings that are either old or don’t respect seismic standards. Our aim is to present a study about seismic risk and seismic scenarios for the city of Al Hoceima. The seismic vulnerability of the existing residential buildings was evaluated using the vulnerability index method (Risk-UE). It was chosen to be adapted and applied to the Moroccan constructions for its practicality and simple methodology. A visual inspection of 1102 buildings was carried out to assess the vulnerability factors. As for seismic hazard, it was evaluated in terms of macroseismic intensity for two scenarios (a deterministic and probabilistic scenario). The maps of seismic risk are represented by direct damage on buildings, damage to population and economic cost. According to the results, the main vulnerability index of the city is equal to 0.49 and the seismic risk is estimated as Slight (main damage grade equal to 0.9 for the deterministic scenario and 0.7 for the probabilistic scenario). However, Moderate to heavy damage is expected in areas located in the newer extensions, in both the east and west of the city. Important economic losses and damage to the population are expected in these areas as well. The maps elaborated can be a potential guide to the decision making in the field of seismic risk prevention and mitigation strategies in Al Hoceima.

The ancient Algerian urban nuclei are composed of different kind of structural systems, such as unreinforced masonry building (URM) buildings, reinforced concrete (RC) buildings, steel buildings and last but not the least the reinforced masonry structures. This type of structure is one of the most vulnerable to seismic action, as they were not built to seismic codes and regulations. In this paper, a contribution for the safety assessment of reinforced masonry buildings under seismic loading is presented. With this purpose, a vulnerability index method has been applied to this type of buildings for the Algerian case according to the national seismic regulations (RPA), by identifying the most important parameters that have an influence on the seismic behaviour of such structures. Weighting factors are then assigned to each parameter in order to evaluate the vulnerability index, which allows classifying each assessed structure according to a suggested classification. The weighting factors were first estimated by a dynamic analysis using ten seismic records. Lastly this method was implemented in a Delphi program and performed using several examples to show its efficiency.

The seismic vulnerability of urban assets exposed to earthquake hazard represents a growing concern in the engineering field due to the potential risk of collapse for the buildings, and the associated devastating consequences for the inhabitants. This concern has led to the development of novel strategies for the assessment of the seismic vulnerability of the existing buildings. An accurate evaluation of the seismic vulnerability constitutes the point of departure for the implementation of the necessary mitigation strategies aimed at increasing the seismic resilience of the cities. Seismic vulnerability assessment (SVA) at large-scale requires robust knowledge of the existing structural typologies, often biased by the intrinsic uncertainties related to local construction materials and techniques, especially in territories composed of historical and vernacular constructions. A propaedeutic stage of SVA is the definition of building taxonomies to characterize the structural features of the buildings and their main sources of vulnerabilities. This difficult task requires the availability of consistent technical data, which are commonly scarce in cities with historical constructions. This doctoral thesis contributes to the development of suitable methodologies for the systematic surveying of urban buildings in historical urban centres, by proposing four complete survey forms for timber, masonry, reinforced concrete and steel/iron structural typologies. This tool aims to improve and optimize the complex process of collecting and gathering data about the structural characteristics of the existing building stock. This thesis also contributed to the calibration of simplified numerical models for the assessment of the seismic vulnerability of traditional buildings composed of timber frame and masonry wall structures. The nonlinear behaviour is simulated through the adoption of Lumped Plasticity Models (LPM) for timber frames, and continuum Finite Element (FE) models for masonry walls. The calibration of these models is pursued based on rigorous comparisons with numerous experimental tests available in the scientific literature. The developed simplified numerical models for timber frame and masonry wall structures are used to assess the seismic vulnerability of two existing buildings located in the historical centre of the city of Valparaíso, Chile. The numerical models are employed afterwards to analyse the different structural configurations of timber-masonry buildings of the study area. The examined structural configurations differ in the organization of the resisting systems, number of storeys, and presence of structural irregularities. The different pushover analyses show the influence of the aforementioned parameters on the seismic behaviour of the buildings. This research proposes a tentative set of scores and weights for the application of the Vulnerability Index Method (VIM) to traditional buildings composed of timber frame and masonry wall structures based on a numerical investigation. The resulting VIM form is calibrated by applying the N2 method to determine the seismic performance of the representative typologies within the study area. This study is based on the results of a numerical study, unlike other available VIM forms available in the existing literature are based on past post-earthquake surveys of damaged buildings. The thesis ends in a prospective study on the seismic vulnerability by VIM of 111 buildings located in three neighbourhoods of the historical centre of Valparaíso. This is an area of special interest, as it includes two of the main evacuation routes for the city in case of a tsunami, and congregate different typologies of heritage buildings, made of timber, masonry, and reinforced concrete. The obtained results are used to create seismic vulnerability maps in a GIS environment that may be used for future works aimed at the definition of proper policies for the implementation of mitigation strategies. La vulnerabilidad sísmica de zonas urbanas expuestas a terremotos representa una creciente preocupación en el campo de la ingeniería debido al potencial riesgo de colapso de los edificios, y las consecuencias devastadoras que afectan a sus habitantes. Esta inquietud ha motivado el desarrollo de nuevas estrategias para la evaluación de la vulnerabilidad sísmica de los edificios existentes en centros urbanos. Un correcto estudio de la vulnerabilidad sísmica constituye el punto de partida para la correcta implementación de estrategias de mitigación enfocadas a aumentar la resiliencia sísmica de las ciudades. Los estudios de vulnerabilidad sísmica a escala urbana requieren un alto nivel de conocimiento respecto a las tipologías constructivas existentes, información comúnmente sesgada por las incertidumbres intrínsecas de los edificios, asociadas a los materiales y técnicas de construcción locales, especialmente en territorios compuestos por construcciones históricas o de naturaleza vernácula. Una etapa propedéutica de este tipo de estudios es la definición de una taxonomía de edificios, que permita caracterizar los sistemas estructurales existentes y detectar sus principales fuentes de vulnerabilidad. Esta tesis doctoral contribuye al desarrollo de una metodología para el levantamiento sistemático de edificios históricos en centros urbanos, basada en la formulación de cuatro formularios de encuestas para tipologías estructurales de entramado de madera, mampostería, hormigón armado y acero/hierro forjado. Otra importante contribución de esta tesis se centra en la calibración de modelos numéricos simplificados y orientados a la práctica para la evaluación de la vulnerabilidad sísmica de edificios tradicionales compuestos por muros de entramados de madera y mampostería. El comportamiento no lineal dichas estructuras es simulado mediante el uso de Modelos de Plasticidad Concentrada para muros de entramado de madera, y modelos continuos de Elementos Finitos para muros de mampostería. La calibración de estos modelos se lleva a cabo en base a rigurosas comparaciones entre diferentes ensayos experimentales disponibles en la literatura científica. Los modelos propuestos se utilizan para la evaluar la vulnerabilidad sísmica de dos edificios existentes situados en el centro histórico de la ciudad de Valparaíso, Chile. Este caso de estudio se caracteriza por su singular entorno urbano, donde predominan los sistemas estructurales compuestos por muros de entramados de madera y mampostería. Los modelos numéricos se utilizan para analizar diferentes configuraciones estructurales de los edificios de entramado de madera y mampostería localizados en tres barrios históricos del centro de la ciudad de Valparaíso. Este estudio examina diferentes configuraciones estructurales que difieren en la organización de los sistemas resistentes, número de plantas y la presencia de irregularidades estructurales. La siguiente etapa de esta investigación propone una calibración preliminar del Método del Índice de Vulnerabilidad (MIV) para edificios de entramado de madera y mampostería. Una nueva ficha de vulnerabilidad se calibra en base a una investigación numérica y en la aplicación del Método N2 para determinar el rendimiento sísmico de los edificios. Esta tesis culmina con un estudio prospectivo de la vulnerabilidad sísmica aplicando el MIV a 111 edificios ubicados en tres barrios del centro histórico de Valparaíso. Esta incluye dos de las principales rutas de evacuación de la ciudad en caso de tsunami y alberga diferentes tipologías de edificios patrimoniales, hechos de entramados de madera, mampostería y hormigón armado. Los resultados obtenidos se utilizan para crear mapas de vulnerabilidad sísmica en el entorno GIS que pueden utilizarse para llevar a cabo planes futuros para la implementación de estrategias de mitigación de la vulnerabilidad.

With the UHV (Ultra High Voltage) power grid construction and the interconnection of regional power grids, the scale of power grids in China is increasing rapidly. At the same time, significant uncertainty and variability is being introduced into power grid operation with the integration of large-scale renewable energy in power systems. All of these pose an enormous challenge to the operation control of power systems in China. For a long time, online static security analysis, as an important part of EMS (Energy Management System), has been an effective tool for power grid operation. However, it is increasingly difficult for traditional static security analysis in serial computing mode to be online applied in bulk power grids in China. A new practical parallel approach for online static security analysis is put forward in this paper. A multithread parallelism is introduced into contingency screening, detailed contingency evaluation and decision support for reducing the execution time. By employing the multithread technology, the hardware resources of multi-processor/multi-core computer can be fully used and the program can be speeded up effectively. The performance of the parallel static security analysis is demonstrated by tests on two large-scale power systems. The test results show that the proposed method can be online applied in real bulk power grids.

The level of safety of groundwater to pollution hazards can be identified based on the level of vulnerability of the groundwater to pollution. Determination of groundwater vulnerability intrinsically can be done by using the Aquifer Vulnerability Index (AVI) method based on two physical parameters i.e. the thickness of each layer above the uppermost of saturated aquifer surface and the estimated hydraulic conductivity of each of these sedimentary layers. The objective of this study was to determine the level of groundwater vulnerability intrinsically based on the vulnerability index value of aquifers by using the AVI method. This study was conducted based on sample of 25 dug wells scattered in the Jombang District of Jombang Regency, East Java, Indonesia. Based on the results of the analysis using the AVI method, it can be stated that the hydraulic resistance logarithm in the study area were found to be in the range from -5.22 to 3.84 with the intrinsic vulnerability of groundwater to pollution hazards from extremely high to low.

Seawater intrusion is one of the major issues in Qeshm Island, which is the biggest island of the Persian Gulf. To investigate seawater intrusion in this island, a modified GALDIT index is used to map the vulnerability of the whole region. Considering the vulnerability map, two critical sections which have the highest vulnerability, one in the northeast and the other in the west side of the island, are chosen for detailed investigation. To achieve this goal, two numerical models, MODFLOW and SEAWAT are applied to simulate the groundwater flow and solute transport. The results show that the aquifer is in a dangerous level of threat of vulnerability and 15 km2 of the aquifer is in danger of being salinized. A comparison is made between MT3DMS and SEAWAT results, indicating that SEAWAT simulates seawater intrusion with more accuracy. It seems because of considering salt density in SEAWAT flow equations. The numerical simulation shows that the seawater is intruding on the island at a rapid rate.

Unreinforced Masonry (URM) structures, such as historic buildings, traditional buildings and ordinary buildings, exist all over the world and constitute a relevant part of the cultural heritage of humanity. Their protection against earthquakes is a topic of great concern among the earthquake engineering research community. This concern mainly arises from the strong damage or complete loss suffered by these types of structures when subjected to earthquake and also from the need and interest to preserve them as a built heritage.
 This paper initially presents a methodology for assessing the seismic vulnerability of URM buildings based on vulnerability index evaluation approach. Moreover, this paper presents the correlation between vulnerability index and Macroseismic method to estimate the physical damage in relationship with seismic intensity. Finally, presents implementation of the methodology to construct vulnerability curves, fragility curves and estimate losses.

Today, scientists are deeply concerned by the vulnerability of groundwater reservoirs to pollution. Relatively simple overlay and index methods can be used to produce groundwater vulnerability maps in geographic information system. In addition, this study deals with contamination from nonpoint sources. In this study, two such models, DRASTIC and GOD, were applied in the Jijel Plain area of northeast Algeria and compared with measured groundwater nitrate concentrations. This showed that results from DRASTIC were better than GOD, 69% correlation with nitrate compared to 56%. DRASTIC was better able to identify vulnerable zones along the river valleys. The DRASTIC model was then modified using the nitrate concentrations to optimize the rating score given within each parameter range and sensitivity analysis to change the weighting given for each parameter. These combined changes gave a final Pearson's correlation of 83% with nitrate. This showed that recharge, aquifer type, and topography were the key factors in controlling vulnerability to nitrate pollution.

Seismic vulnerability assessment of stone masonry façade walls: Calibration using fragility-based results and observed damage

Seismic vulnerability assessment for the historical areas of the Timisoara city, Romania

Coastal areas are highly dynamic environments facing increasing threats from both natural processes and human activities, such as coastal erosion, sea level rise, and land use changes. Prancak Village is one such coastal area vulnerable to geomorphological changes. This study aims to assess coastal vulnerability through geomorphological analysis using the Coastal Vulnerability Index (CVI) method. Data were collected from primary and secondary sources, including satellite imagery, field surveys, digital elevation models (DEMs), and data from relevant agencies. The analyzed parameters comprised coastal morphology, beach slope, shoreline change, wave height, and tidal range. The CVI calculation yielded a value of 6.93, which falls within the 5.8–10.06 range classified as “low vulnerability” (20–40% vulnerability level), indicating that the study site has relatively low susceptibility to the physical factors assessed Although the overall index is low, local physical dynamics still pose risks in certain areas, confirming that geomorphology and coastal ecosystem conditions are more decisive in determining vulnerability than oceanographic parameters such as wave height.

Coastal areas are inherently sensitive and dynamic, susceptible to natural forces like waves, winds, currents, and tides. Human activities further accelerate coastal changes, while climate change and global sea level rise add to the challenges. Recognizing and safeguarding these coasts, vital for both socioeconomic and environmental reasons, becomes imperative. The objective of this study is to categorize the coasts of the Mersin and İskenderun bays along the southeastern coast of Türkiye based on their vulnerability to natural forces and human-induced factors using the coastal vulnerability index (CVI) method. The study area encompasses approximately 520 km of coastline. The coastal vulnerability analysis reveals that the coastal zone comprises various levels of vulnerability along the total coastline: 24.7% (128 km) is categorized as very high vulnerability, 27.4% (142 km) as high vulnerability, 23.7% (123 km) as moderate vulnerability, and 24.3% (126 km) as low vulnerability. Key parameters influencing vulnerability include coastal slope, land use, and population density. High and very high vulnerability are particularly prominent in coastal plains characterized by gentle slopes, weak geological and geomorphological features, and significant socioeconomic value.

Purpose of this research to know 1) the level of social vulnerability, 2) socio economic description, and 3) mapping of comparison of social vulnerability in Watershed of Bengawan Solo covering Bojonegoro, Tuban, Lamongan and Gresik. The method used in this research by using Social Vulnerability Index (SoVI) method as social vulnerability analysis tool and Geography Information System (GIS) analysis tool to map the area and its vulnerability level. The results showed the highest level of social vulnerability with the highest score of SoVI score obtained by Tuban Regency with SoVI score of 7, then Bojonegoro with SoVI score of 6, Lamongan with SoVI score of 4, and Gresik with SoVI score of 1. Bojonegoro And Kabupaten Tuban have the same highest score on the components of social vulnerability level, then Lamongan regency, and the lowest level of social vulnerability is in Gresik regency. For the grade of social vulnerability, Kabupaten Tuban and Bojonegoro are categorized into high social vulnerability classes, Lamongan District with moderate social vulnerability, and Gresik Regency with the lowest social vulnerability.

West Pasaman has rich coastal potency. Marine resources and coastal tourism become income source for this regency. Besides the potency, West Pasaman Coast also vulnerable because it lays on tectonic path subduction and bordered with Hindia Ocean that triger abration, earthquake and tsunamis. The combinations of high abration and flat coast with mud and sand make the West Pasaman Coast very vulnerable. Extreme weather and dense population with convensional living in the coastal area create the complexity of coastal problems. Early, The Coastal Vulnerability Index (CVI) is a method to analyze coastal vulnerability based on certain factors i.e ocean hydrodinamics and coastal morphology. But nowadays, to minimize the risk of natural disasters, the CVI has been modified with additional factors. This research aims to analyze the coast vulnerability of West Pasaman Coast using Coastal Vulnerability Index (CVI) method based on GIS. The study use primary and secondary data. The field survey was conducted on April 2019 with purposive sampling method at 6 districts and 10 sites as the observation points. Those districts are Sungai Beremas, Koto Balingka, Sungai Aur, Sasak Ranah Pasisir, Luhak Nan Duo and Kinali. The result shows that Kinali Coast is categorized as high vulnerability (CVI 3.95) and other 5 districts are moderate vulnerability (CVI 2.3-2.9).