Vulnerability Curves For Buildings Research Articles

Development of vulnerability curves of buildings to windstorms using insurance data: An empirical study in South Korea

Windstorms have caused a range of damage on the built environment. Although several risk assessment models for estimating such damage have been widely developed, the results generated by these models often turn inaccurate due to the building information required for such models at a regional scale are usually incomplete, or of a poor quality. Alternatively, this study utilizes an insurance company's loss data pertaining to the high winds of Typhoon Maemi in South Korea in 2003 for calculating building damage in terms of damage ratios. Next, these damage ratios and storm-wind speeds are utilized for constructing vulnerability curves that can be used to predict levels of damage to designated building types subject to given wind speeds. Lastly, geographical information systems spatial data is combined with those vulnerability curves to arrive at four distinct wind-damage levels. It is hoped that the present research will serve as a reference for further studies of developing building vulnerability curves for storm winds.

Assessment of Building Vulnerability Curve Subjected to Debris-Flow

In this study, the vulnerability curves for masonry and concrete frame buildings are assessed based on building fragility curves for the debris-flow caused by landslides on mountain slopes. The First-Order Second-Moment (FOSM) method is used to estimate the building fragility curve (expressed as probability of damage exceedance) subjected to debris-flow. In this method, the horizontal displacement of a building impacted by debris-flow and the statistics of resistance (i.e., building displacement) following four different damage states (i.e., slight, moderate, extensive, and complete) are utilized to estimate the building fragility curve. The building vulnerability curves (expressed as mean probability of damage) were evaluated based on the estimated building fragility curve and corresponding mean damage ratio for each damage state and were verified by calculating the root mean square error with datasets obtained from post-disaster damage assessment. In this study, the effects of structural material, type, and height on the building vulnerability curves were also studied. All vulnerability curves of buildings estimated in this study were fitted and databased using parameters of the log-normal cumulative distribution function and can be used to measure the performance of buildings in debris-flow prone areas as well as to provide information for risk and loss assessment.

Estimating the casualties of the earthquake caused by the Lembang Fault in Coblong, Bandung, Indonesia

Bandung is a metropolis in Indonesia located 10 km from the Lembang Fault. Being near a fault and having a dense population places Bandung at a high risk of suffering an earthquake. The lack of an earthquake risk assessment for the Lembang Fault is the main motivation of this study, which aims to provide information on the risk of building damage and estimated casualties in the Coblong District. This study uses earthquake scenarios with magnitudes of 6 and 7 caused by the Lembang Fault. Earthquake acceleration data on bedrock along with building vulnerability curves are used to obtain the probability of building damage. The number of victims is calculated based on the level of building damage using the event tree model from the HAZUS method. The results of the calculation show that the Lembang Fault earthquake with a magnitude of 6 could cause casualties in Coblong amounting to around 0.6% of the population, rising to as much as 1.5% for a magnitude of 7. The level of building damage is 36.6% and 55.6%, respectively.

Empirical fragility and vulnerability curves for buildings exposed to slow-moving landslides at medium and large scales

Slow-moving landslides yearly induce huge economic losses worldwide in terms of damage to facilities and interruption of human activities. Within the landslide risk management framework, the consequence analysis is a key step entailing procedures mainly based on identifying and quantifying the exposed elements, defining an intensity criterion and assessing the expected losses. This paper presents a two-scale (medium and large) procedure for vulnerability assessment of buildings located in areas affected by slow-moving landslides. Their intensity derives from Differential Interferometric Synthetic Aperture Radar (DInSAR) satellite data analysis, which in the last decade proved to be capable of providing cost-effective long-term displacement archives. The analyses carried out on two study areas of southern Italy (one per each of the addressed scales) lead to the generation, as an absolute novelty, of both empirical fragility and vulnerability curves for buildings in slow-moving landslide-affected areas. These curves, once further validated, can be valuably used as tools for consequence forecasting purposes and, more in general, for planning the most suitable slow-moving landslide risk mitigation strategies.

Insights into the possible seismic damage of residential buildings in Bucharest, Romania, at neighborhood resolution

Seismic loss estimation analysis for large cities is a very demanding yet necessary task; the modelling of such complex systems requires first of all insightful input data at good resolution, referring to local effects, buildings and socio-economic aspects. Also, the implementation of less empirical estimation methods is needed. Until recently, these requirements could not be fulfilled for Bucharest, the capital city in the European Union which is most at risk due to earthquakes. Based on 2011 and 2002 census data, standardized according to the framework of the Near-real time System for Estimating the Seismic Damage in Romania (SeisDaRo) through a unique approach, and on relevant hazard scenarios, we estimate for the first time the building damage at census tract scale. The methodology applied relies on 48 vulnerability curves for buildings, on the Improved Displacement Coefficient Analytical Method included in the SELENA software for computing damage probabilities and on deterministic seismic hazard scenarios, including the maximum possible earthquake. By using overlay analysis with satellite imagery and a new methodology integrated in GIS we show how results can be enhanced, reflecting more localized characteristics. Best practices for seismic risk mapping are also expressed. The results are promising and contribute to mitigation efforts in Bucharest.

Building vulnerability to debris flows in Taiwan: a preliminary study

In quantitative risk analyses for natural hazards, vulnerability can be expressed as the ratio of reconstruction, replacement or reproduction expenses due to a damage caused by a certain process intensity and the original value of the element at risk exposed. To discuss the building vulnerability under debris flow events, the ratio is mostly related to debris flow inundation height, building materials and building values. Different types of buildings would resist to the impact of debris flows differently, resulting in different damage levels even under the same inundation height. After debris flow events, the damages to a building include the content loss and the structure loss, which is also variable due to the individual building conditions. This study proposes a flowchart to establish building vulnerability curves through estimating the damages to buildings after debris flow hazards. The losses of content and structure are firstly calculated separately to obtain the loss ratios with respect to original buildings. Secondly, by combining the content and structure loss ratio, the building vulnerability function is derived. In this paper, the original building content value was obtained from governmental statistic records and was based on the market price, and the structure value was received from a regional architecture office. The losses resulting from debris flow impacts were synthetically derived following field surveys. To combine the content and structure losses, a unit building with a floor area of 60 m2 was assumed. The result shows that due to a higher percentage of content value compared with the total building value, the loss ratio resulting from debris flows in Taiwan is higher compared with European studies, in particular with respect to high-frequency but low-magnitude events. The concept of obtaining building vulnerability is particularly suitable for regions where well-documented building loss records are unavailable.

Experimental vulnerability curves for the residential buildings of Iran

Iran is one of the most seismically active countries of the world located on the Alpine-Himalayan earthquake belt. More than 180,000 people were killed due to earthquakes in Iran during the last five decades. Considering the fact that most Iranians live in masonry and non-engineered houses, having a comprehensive program for decreasing the vulnerability of society holds considerable importance. For this reason, loss estimation should be done before an earthquake strikes to prepare proper information for designing and selection of emergency plans and the retrofitting strategies prior to occurrence of earthquake. The loss estimation process consists of two principal steps of hazard analysis and vulnerability assessment. After identifying the earthquake hazard, the first step is to evaluate the vulnerability of residential buildings and lifelines and also the social and economic impacts of the earthquake scenarios. Among these, residential buildings have specific importance, because their destruction will disturb the daily life and result in casualties. Consequently, the vulnerability assessment of the buildings in Iran is important to identify the weak points in the built environment structure. The aim of this research is to prepare vulnerability curves for the residential buildings of Iran to provide a proper base for estimating probable damage features by future earthquakes. The estimation may contribute fundamentally for better seismic performance of Iranian societies. After a brief review of the vulnerability assessment methods in Iran and other countries, through the use of the European Macroseismic method, a model for evaluating the vulnerability of the Iranian buildings is proposed. This method allows the vulnerability assessment for numerous sets of buildings by defining the vulnerability curves for each building type based on the damage observations of previous earthquakes. For defining the vulnerability curves, a building typology classification is presented in this article, which is representative of Iranian building characteristics. The hazard is described in terms of the macroseismic intensity and the EMS-98 damage grades have been considered for classifying the physical damage to the buildings. The calculated vulnerability indexes and vulnerability curves show that for engineered houses there is not any notable difference between the vulnerability of Iranian and Risk-UE building types. For the non-engineered houses, the vulnerability index of brick and steel structures is less than the corresponding values of the other unreinforced masonry buildings of Iran. The vulnerability index of unreinforced and masonry buildings of Iran are larger than the values of the similar types in Risk-UE and so the Iranian buildings are more vulnerable in this regard.

Deterministic earthquake damage and loss assessment for the city of Bucharest, Romania

On March 4, 1977, an earthquake with a moment magnitude Mw 7.4 at a hypocentral depth of 94 km hit the Vrancea region (Romania). In Bucharest alone, the earthquake caused severe damage to 33,000 buildings while 1,424 people were killed. Under the umbrella of the SAFER project, the city of Bucharest, being one of the larger European cities at risk, was chosen as a test bed for the estimation of damage and connected losses in case of a future large magnitude earthquake in the Vrancea area. For the conduct of these purely deterministic damage and loss computations, the open-source software SELENA is applied. In order to represent a large event in the Vrancea region, a set of deterministic scenarios were defined by combining ranges of focal parameters, i.e., magnitude, focal depth, and epicentral location. Ground motion values are computed by consideration of different ground motion prediction equations that are believed to represent earthquake attenuation effects in the region. Variations in damage and loss estimates are investigated through considering different sets of building vulnerability curves (provided by HAZUS-MH and various European authors) to characterize the damaging behavior of prevalent building typologies in the city of Bucharest.