Seismic Vulnerability Assessment Research Articles

Vulnerability and Seismic Exposure of Residential Building Stock in the Historic Center of Alcamo

The influence of exposure evaluation methodology in the assessment of the seismic vulnerability of the residential building stock in the historic center of Alcamo, a town of 45,000 inhabitants in Western Sicily (Italy), hit by an earthquake in 1968, is evaluated in this study. A comparison of exposure estimates on the basis of the description of the residential building stock according to two different approaches is performed. The first, typical of seismic vulnerability assessment procedures at a territorial scale, refers to the description of residential building stock through an accurate typological description, conducted using the CARTIS survey form. The form allows for a detailed description and survey of the prevailing ordinary building types within areas characterized by the homogeneity of the building fabric in terms of age of construction, structural characteristics, construction techniques, and distribution of types. The detailed description of building types allows for the assessment of exposure at the municipal scale based on an estimate of the total number of units and the percentage of each type within each compartment, obtained by interviewing local technicians. The second is based on a similar survey at the building scale, namely, drawing up a form for each building. The comparison of exposure and damage scenarios obtained with the two methods proves that the approximations provided by the compartment-scale survey are compatible with the purposes of an assessment of vulnerability and damage scenarios at the territorial scale.

Classification of buildings' potential for seismic damage using a machine learning model with auto hyperparameter tuning

The research on the application of machine learning (ML) methods in the field of earthquake engineering shows a continuous and rapid progress in the last two decades. ML methods and models belonging to the category of supervised, unsupervised and semi-supervised learning are applied for the assessment of seismic vulnerability of structures and estimation of the expected level of seismic damage. These models lead to the classification of seismic damage into predefined classes through the extraction of patterns from data collected from various sources. However, the lack of detailed knowledge can affect their performance and ultimately reduce their reliability, as well as the generalizability that should characterize them. Towards this direction, the present paper attempts to compare and evaluate for the first time the ability of an extensive number of ML methods in the correct classification of R/C buildings at the first stage pre- and post-seismic inspection considering three seismic damage categories. A database consisting of 5850 training samples is used for this evaluation. This database is generated by solving 90 R/C buildings for 65 actual seismic excitations applying nonlinear time history analyses. For each one of the training samples the maximum interstory drift ratio is calculated as a damage index. In addition, a major contribution of this paper is the presentation and extensive documentation of the procedures required for the preprocessing of the data. Finally, an auto hyperparameter tuning method for the winning algorithm is proposed, so that the hyperparameters are automatically optimized utilizing Bayesian Optimization. The most significant conclusion extracted is that the studied ML algorithms extract very different classification results. In addition, the Support Vector Machine - Gaussian Kernel algorithm extracted the most accurate results of all the studied ML algorithms.

A Machine-Learning-Based Seismic Vulnerability Assessment Approach for Low-Rise RC Buildings

ABSTRACT Seismic vulnerability evaluation of existing buildings is essential to minimize the destructive impacts of earthquakes. Rapid visual screening (RVS) methods are simple and effective vulnerability assessment techniques to help quickly identify high-risk buildings for more detailed evaluations. Among various RVS methods, the Hassan–Sozen priority index (PI) is one of the simplest methods that can be used for low-rise reinforced concrete (RC) buildings. The PI relates simple, easily attainable geometric features of a building including number of stories, floor area, column area, and wall area to damageability. However, the relationship is overly simplified, and there is no absolute basis for defining damage classification boundaries that can be used to interpret the PI. Furthermore, given the lack of seismic parameters as inputs, the PI only allows for a relative evaluation of buildings in a specific region. To address these issues and develop a more broadly applicable RVS method, this study first proposes an improved PI evaluation method using machine learning techniques to define damage classification boundaries. Then, a new generalized RVS method is proposed that considers the PI input features and earthquake intensity measures to predict damage states. Data from six post-earthquake damage surveys (Duzce (1999), Bingol (2003), Nepal (2015), Taiwan (2016), Ecuador (2016), and Pohang (2017)) are used to train and evaluate the classification models. Two earthquake intensity features, modified Mercalli intensity and peak ground acceleration, are introduced to develop a new earthquake intensity aware RVS. The results of the proposed methodologies show a considerable improvement from the original PI with no judgment needed to define the damage classification boundaries.

Comparison of Numerical Strategies for Historic Elevated Water Tanks: Modal Analysis of a 50-Year-Old Structure in Italy

The seismic vulnerability assessment of existing structures is a well-known challenging task, due to a combination of several aspects. The use of analytical or finite element (FE) numerical models can offer robust support in this analysis but necessitates the accurate calibration of geometrical and mechanical input, with related uncertainties. In this paper, attention is focused on the identification of dynamic parameters, based on modal numerical analysis, of a 50-year-old, reinforced concrete, elevated water tank (EWT) characterised by a reservoir with a truncated cone shape. The structure is located in a high seismic region of northern Italy and presently necessitates retrofit plans to preserve its functionality. Based on the limited available experimental evidence and technical drawings, major efforts are spent for the numerical prediction of fundamental vibration modes and frequencies of the structure, which represent a first key step for seismic analyses, under various water-filling levels. To this aim, four different FE numerical strategies able to include both structural features and possible fluid–structure interaction (FSI) effects are developed. By progressively increasing the computational cost (and expected the accuracy of the solutions), FE models based on added-mass (M0 model), spring-mass (M1-DM or M1-DS models), or acoustic (M2 model) strategies are taken into account and combined with increasing detailing in geometrical description of the structure. Results from parametric modal analyses are discussed for the case-study EWT, in terms of computational cost, possible numerical limitations, accuracy of predicted frequencies/modal shapes, sensitivity to water-filling levels and operational configurations, with the support of several pieces of experimental evidence and consolidated analytical formulations for fundamental frequency estimations.

Knowledge-Based Investigation of Seismic Vulnerability Assessment and Compatible Strengthening Design of an Existing Masonry Building

Most existing masonry buildings were built without following code regulations for seismic criteria. Hence, their performance compared to the demands of the current codes, for both seismic and static actions, could be very low. In engineering practice, strengthening interventions can be pursued at different levels, based on qualitative assessments of masonry structures. Firstly, the structures are evaluated through in situ inspections. Then, based on the structural system of the building a strengthening design is proposed. The design can be targeted at guaranteeing a box behavior of structures acting through macro-elements, or at strengthening the in-plane capacity of piers and spandrels. However, lower cognitive levels may drive inaccurate impressions about the capacity of structures, leading to unreliable strengthening solutions. While in some cases the confidence factor could underestimate the effects of the reinforcements, in other cases lower knowledge levels could lead to incorrect reinforcements that do not provide helpful solutions. In this paper, the issues concerning the strengthening design of masonry structures are presented and discussed with regard to an existing building. The construction is a 20th century masonry building used as a nursing home for elderly persons. The study follows a knowledge-based procedure where, after achievement of the highest knowledge level and the proposal of compatible and effective strengthening interventions, the analysis of the potential effects of achieving lower knowledge levels is discussed both in terms of vulnerability computations and in terms of strengthening effectiveness. Regarding vulnerability assessment, a lower knowledge level leads to non-conservative results, with an increase in the estimated capacity of around 80%. Critical evaluation of the different configurations for the case study makes it clear that for the considered masonry building the mortar investigation represented the most important parameter to be investigated. The proposal of strengthening interventions before assessment of this parameter may lead to ineffective improvements resulting in index values lower than 0.60. The study represents the opportunity to assess comparisons in the setting of different investigation strategies and their effect on the definition of the strengthening solutions.

Seismic Risk Assessment of Simply Supported Girders Bridges

Abstract Transport infrastructures, such as bridges, located in seismically active regions are potential exposure due to seismic hazards. A bridge collapse can have tremendous consequences because they provide vital links in a transportation system. Cross border region historically is very well known as territory characterized with high seismic risk. For that purpose, this study is related to the identification of seismic hazard cross-border harmonization vulnerability assessment of risk based on defined levels of seismic hazard and definition of reliable risk of simply supported girders bridge, which is main typology scheme. This study presents an analytical method to predict damage exceedance probabilities due to seismic events using the development of fragility curves. The proposed framework is demonstrated by performing case study highway bridges located in cross border Albanian region with Greece and North Macedonia. Bridge hazard identification is defined by established each damage state of probabilistic structural capacity. The damage probabilities of exceedance that structural demand exceeds capacity are analyzed, displaying results in the fragility curves of bridges.

Evaluation of seismic vulnerability assessment building using rapid visual screening method: case study at the Faculty of Islamic Economics and Business of Islamic State Prof. KH. Saifuddin Zuhri University

Indonesia is one of the nations that is more prone to earthquakes due to its location at the intersection of the Indo-Australian, Eurasian, and Pacific plates. This study aims to find out the vulnerability and final score of the Faculty of Islamic Economics and Business of Islamic State Prof. KH. Saifuddin Zuhri University used the RVS method based on FEMA P-154, where this method is one of the earliest methods used to evaluate the vulnerability of a building, and has a final value limit of 2. If the final score is more than 2, then the building under review has a low vulnerability to earthquakes and vice versa. This building is one of the mid-rise buildings in Purwokerto which was established in 2019. Based on RVS analysis, the final score was 3.6 for the category of concrete moment-resisting frames (C1) and 1.4 for the category of concrete frames with unreinforced masonry infill walls (C3). Thus, the results showed this 6-story building has a vulnerability to earthquakes with a high category of a high probability of damage to level 3 and a very high probability of level 2 damage.

Seismic Vulnerability Assessment of RC Frame Buildings Designed Using the DDBD Approach: A Parametric Study

Seismic Vulnerability Assessment of RC Frame Buildings Designed Using the DDBD Approach: A Parametric Study

The Seismic Vulnerability Assessment of Heritage Buildings: A Holistic Methodology for Masonry Churches

ABSTRACT The seismic vulnerability assessment of monumental buildings is a complex task. Several uncertainties mine the reliability of evaluations. Within historical buildings, churches appear as particularly vulnerable objects, prone to instabilities and collapse when undergoing seismic loads. Global and local collapse mechanisms related to in plane and out-of-plane response of walls, respectively, are commonly observed in existing masonry buildings subjected to a seismic event. The main cause is the lack of strong connections among orthogonal walls and between walls and floors, which does not allow a global box-type behaviour of the building. This paper shows an approach to evaluate the vulnerability of churches based on a three-step analysis with increasing detail. The first step is a large-scale analysis to be applied to sets of churches, based on a simplified form comparing 28 mechanisms that can be activated by seismic events. The second step is referred to the evaluation of single churches and related, based on a kinematic approach, to the possibility to have out-of-plane mechanisms. The third step is based on the results of numerical models. It is useful to evaluate the behaviour in detail of some macroelements and to validate the obtained results in the first two steps.

Seismic vulnerability assessment of steel storage tanks protected through sliding isolators

AbstractAn adequate seismic protection of steel storage tanks of industrial, chemical and petrochemical plants is essential since potential consequences of failures, besides the economic losses, can be catastrophic for the environment and for people living nearby. Among the most common damages suffered by steel tanks in recent earthquakes, there are the elephant‐foot‐buckling of the perimeter wall and the tanks’ uplift or overturning. Due to the uncertainties related to the estimation of the mechanical properties of filled tanks and related seismic loads (i.e. dynamic overpressures generated by the content), conventional design approaches may lead to unsafe or, on the contrary, oversized solutions. Among effective alternatives, base isolation through Curved Surface Slider isolators (CSSs) offers some valuable advantages like high load bearing and displacement capacity with compact dimensions, independence of the oscillation period on the supported mass, and minimisation of torsional effects. Despite being neglected by most common commercial FEM codes, as a drawback, recent studies pointed out that the initial peak of friction force at CSSs’ motion breakaway can lead to significantly increased lateral deformations and accelerations of the superstructure. Within this framework in this study, a refined numerical model is developed in OpenSees FEM code, and an exhaustive parametric study is carried out to investigate the effect of the breakaway on isolated tanks providing some useful insights for the selection of the most suitable isolators.

Vulnus Web: A Web-Based Procedure for the Seismic Vulnerability Assessment of Masonry Buildings

Masonry is a widespread construction system, but it is very prone to seismic damage. In Italy, almost 60% of residential buildings are constructed in masonry, and 85% of them were built before 1980 without specific design regulation; thus, there is the need for large-scale vulnerability assessment. When large stocks of residential buildings (>50–100) are involved, also in historical centers, seismic vulnerability analysis must resort to simplified and computer-aided methods. Among these, the best known analyze (i) the overall shear strength normalized to the weight; (ii) the activation coefficient of local mechanisms; and (iii) dimensionless indexes obtained from the weighted sum of scores associated with a set of vulnerability factors. The Vulnus procedure proposes a vulnerability function in the 3D space defined by these factors, namely VIP, VOP and VV. The ‘mechanical’ indexes VIP and VOP determine the capacity of the building (in-plane and out-of-plane, respectively), whereas the ‘empirical’ index VV sets the pace at which this capacity is reached and the uncertainty in its final value. The procedure considers the confidence level of the indexes by means of fuzzy set theory, which enables expression of the vulnerability in linguistic terms (e.g., ‘high’ or ‘low’), as well as through a fragility curve. In this paper, a web toolbox based on the Vulnus procedure, namely, Vulnus Web, is proposed. It enables the central archiving of data, improved interaction with the program code and a wider dissemination. The new procedure was applied to a masonry building hit by the Central Italy 2016 earthquake; both the vulnerability level assessed numerically and the damage prediction were in good accordance with the actual seismic performance of the building.

Using remote sensing for exposure and seismic vulnerability evaluation: is it reliable?

ABSTRACT Conducting field surveys for exposure and seismic vulnerability evaluation is the most costly, resource-intensive task when assessing earthquake risk. During the past decade, risk analysts have been trying to alleviate this using remote sensing for building characterization. However, the use of vulnerability databases created with remote sensing had not been sufficiently validated thus far. In this paper, we have created an exposure and seismic vulnerability database in Port Prince (Haiti) using freely accessible aerial ortho-imagery and LiDAR points. We have validated this database against two reference datasets from different, independent studies. Then, we have computed an earthquake damage scenario to test whether remotely sensed data are actually valid for seismic risk evaluation. We have seen how our vulnerability database yields an accurate damage distribution with a low Mean Absolute Percentage Error of 3.78% when compared to the damage obtained with the reference vulnerability dataset. Further, we have conducted a thorough comparison of the cost that entails creating a vulnerability database using remote sensing with a traditional field survey. Twelve international experts have collaborated in the cost estimation of a typical in-field building inspection. As a result, we have found that using remote sensing techniques allows for saving up to 75% of the cost and 85% of the time. These outcomes seem to prove both, the technical and economic feasibility of remote sensing for seismic vulnerability assessment. Thus, we have proposed a 5-step approach for evaluating building vulnerability that combines both, the analysis of remotely sensed data and a reduced, targeted field survey to optimize time and cost. The final goal is to help cities reach the Sustainable Development Goal nr. 11.B to increase their resilience against disasters.

On the Seismic Vulnerability Assessment of Urban Areas Using Census Data: The Lisbon Metropolitan Area as a Pilot Study Area

ABSTRACT This paper presents a procedure for the application of an index-based vulnerability assessment method to the seismic risk assessment of 292,978 reinforced concrete and 152,916 unreinforced masonry buildings in the Lisbon Metropolitan Area (LMA). A singular innovation of this proposed methodology is that it is tailored to be fed with data from the 2011 national population and housing Census. The vulnerability results are then combined with the seismic hazard component into a GIS tool used to map seismic risk across the LMA. The spatial representation of these results highlights the areas of different levels of vulnerability and risk.

Assessment of Seismic Vulnerability in Urban and Rural Health Service Centers of Hamadan Province Using Geographic Information Systems

Background: Maintaining the performance of healthcare centers during an earthquake is essential. Evaluating the seismic vulnerability of these centers is a priority. This study aims to evaluate seismic vulnerability using geographic information systems (GIS) in urban and rural health service centers of Hamadan Province, Iran, in 2021. Materials and Methods: This is a descriptive, analytical cross-sectional study that was conducted in comprehensive health centers. The data of this study were collected in the form of a questionnaire and a map and analyzed using the hierarchical analysis model. In the study, 10 criteria, such as the type of materials, the age of the building, the quality of the building, the number of floors, the area of ​​the centers, as well as the distance from the existing fault lines, and the proximity to the hazardous centers, are defined using a valuation questionnaire, using the chain analysis method, weighting and prioritizing, and using GIS, vulnerability maps of comprehensive urban and rural health centers of Hamadan province were obtained. Results: Among the indices, the distance from the fault index with a weight of 0.328 has the highest and the area distance with a weight of 0.17 has the lowest final weight. The vulnerability distribution of the centers included 46.99% very low vulnerability, 7.23% low vulnerability, 5.42% moderate vulnerability, 20.48% high vulnerability, and 19.88% very high vulnerability. Conclusion: Considering that many urban and rural health service centers are vulnerable to seismic hazards, it is necessary to strengthen vulnerable centers against earthquakes.

Seismic Vulnerability Assessment of Deteriorating Pile Foundations in Marine Environments

Seismic Vulnerability Assessment of Deteriorating Pile Foundations in Marine Environments

Rapid assessment of seismic vulnerability of historic masonry structures through fragility curves approach and national database data

The research focuses on shared built heritage, which forms one of the most vulnerable parts of the building stock in historic centres. To prevent severe damage to this building category and to aid decision-making, the paper presents a rapid seismic vulnerability assessment procedure based on an engineering approach to safety assessment. The construction of fragility curves is developed on a probabilistic framework on the computed set of Safety Factors over a range of considered Peak-Ground-Accelerations. Input data necessary for the computations are extracted from CARTIS database. The methodology is implemented in a spreadsheet combined with a script in Visual Basic for Applications. Two case studies are used to demonstrate the applicability to a single building and at the territorial scale. Results show that the proposed methodology allows for a rapid testing of loss of structural performance given various scenarios, as well as contributing by prioritizing interventions in probabilistic terms.

Seismic vulnerability and risk assessment at the urban scale using support vector machine and GIScience technology: a case study of the Lixia District in Jinan City, China

The increase in the number and severity of seismic disasters has put communities in danger, especially in rapidly developing and densely populated areas. Traditional seismic vulnerability and risk assessment methods, including field investigation, are accurate at the building scale; however, their low-efficiency and high-cost characteristics limit the application of these methods in urban-scale regions with high-speed development and risk exposure. To address this issue, multisource remote sensing interpretation, support vector machine (SVM) and geographic information science (GIScience) technologies are combined to test the performance and efficiency of a urban-scale macroscopic seismic vulnerability and risk assessment method in the Lixia District of Jinan City, Shandong Province, China, which is characterized by rapid development, a variety of building types, and moderate-to-low seismic risk. First, a traditional field survey was conducted in Lixia District, and a building attribute information database was constructed. Second, the vulnerability proxies of building attribute information and building seismic vulnerability were estimated based on the EMS-98 standard and the SVM. Finally, vulnerability proxies established based on the RISK-UE model were applied to the Lixia database, and the vulnerability and risk assessment under different seismic intensities were estimated with the experimental accuracy verified. The results showed that the SVM method can obtain stable and accurate results in urban scale vulnerability assessment. The mean building vulnerability index in Lixia District is 0.43, which indicates that the overall seismic performance is good. Most of the area falls within the seismic intensity range of VII-X degrees and would experience slight to moderate damage. The results of the study contribute to enhancing the precision and efficacy of large-scale seismic risk assessment, and they can be used by relevant departments to create tailored emergency plans and reduce seismic hazard losses. Additionally, these results can aid in achieving the climate action goal (SDG13) of the United Nations Sustainable Development Goals (SDGs).

A Methodology for Assessing the Component-Level Fragility Curves and Its Application to a Class of Integral Abutment Bridges

Seismic vulnerability assessment of structures is a major research area and the output, i.e., fragility curves (FCs), within a probabilistic framework, devises effective seismic disaster mitigation. The present study proposes a novel methodology for obtaining the structural component-level FC through two new approaches with respect to the assessment of seismic demand and the computation of fragility. The present study evolves an existing nonlinear static method by a few steps to be able to assess the probabilistic demands and develops a numerical computation technique that exploits the actual profiles of the evaluated distributions of the structural capacity and demand data in a study to obtain the fragility magnitudes. The substitute methodology is implemented to derive the FCs of a class of integral abutment bridges while assessing the demands in a simple manner and avoiding the complexities of dynamic analysis and yet with reliable precision as well as averting the misjudgment of fragilities stemming from the lognormal or normal fit on the data, which are practically very rough fit or misfit to it, as imposed in the traditional fragility formulation.

Reconnaissance surveys after June 2022 Khost earthquake in Afghanistan: implication towards seismic vulnerability assessment for future design

Reconnaissance surveys after June 2022 Khost earthquake in Afghanistan: implication towards seismic vulnerability assessment for future design

Typological fragility analysis of masonry buildings in Emilia Romagna region (Italy)

UnReinforced Masonry (URM) buildings constitute the majority of the Italian building stock and represent one of the most vulnerable construction typologies, as emerged during the seismic events occurred in the last decades. The objective of the present work is the proposal of a methodology for the seismic vulnerability and fragility assessment of different typologies of URM buildings. Through the statistical analysis of post-earthquake damage survey forms and of census data, the most prevalent structural typologies were identified in the Emilia Romagna region (Italy), leading to the definition of two reference masonry buildings, built at the beginning of the XX century and representative of the building stock of the study area. These buildings were modeled according to the equivalent frame method and their seismic performance was studied by means of nonlinear static analyses, considering uncertainties on the mechanical properties of masonry, on the intensity of the seismic action and on the displacement demand calculation method. Through the definition of Response Surfaces, analytical fragility curves relative to the investigated structural typologies were determined for the different damage states.