Seismic Vulnerability Assessment Methods Research Articles

COMPUTATIONAL IMPLEMENTATION FOR SEISMIC ASSESSMENT OF EXISTING STRUCTURES

Increasing of seismic record in Brazil resulted in first Brazilian code of seismic NBR 15421:2006. Once publication succeed Brazilian sample building assessment must be developed in order to prevent or mitigate effects of horizontal accelerations from seismic. For preliminary screening of existent reinforced concrete structures qualitative Hirosawa method seems to be suitable to Brazilian reality. This paper aims to implement computationally seismic vulnerability assessment method in order to optimize assessments through opensource SMath Solver and programming language is C#. Adapted Hirosawa method compares resistance of building through seismic index of structure and Seismic demand index . Index is a product of indexes (Basic seismic index of structure, Irregularity index, Time index) and index is formed by zone index, ground index and usage index. Model structure proposed by literature are analyzed in different levels of seismic acceleration as well as types of soil defined by Brazilian seismic code in order to demonstrate usability of tool. Graphical interface and results obtained from the application are showed aiding in decision-taking about new refined assessments or feasible interventions.

A mechanical-based seismic vulnerability assessment method with an application to masonry structures in Cosenza (Italy)

AbstractThe paper presents a mechanical-based framework for the evaluation of local-scale seismic fragility curves. The approach is oriented to a seismic vulnerability assessment of unreinforced masonry buildings and makes use of basic exposure data easily obtained from survey or available in existing database. An efficient finite element model and static nonlinear analyses are employed to assess the structural behaviour. The mechanical-based fragility curves are evaluated using Monte Carlo simulations that allow to account for the uncertainties propagation. The proposed approach is tested on a case-study regarding the city centre of Cosenza, in southern Italy, using exposure information available from CARTIS database.

Seismic vulnerability assessment of RC buildings at compartment scale: the use of CARTIS form

Large-scale seismic vulnerability assessment methods allow to classify the vulnerability of groups of buildings according to recurring parameters. The parameters necessary for the application of these methods may come from the adoption of survey forms. The 1st level CARTIS survey form collects the parameters of an area (town compartment) characterized by homogeneity among building types. The variation of the parameters within the same compartment may lead to the definition of several typological-structural groups of buildings, which can be characterized by different vulnerability. Therefore, the assessment of the seismic vulnerability of a compartment requires knowing the distribution of different typologies and their relative structural performance. In this work the vulnerability is evaluated at town compartment level starting from the vulnerability of the RC building typologies, by applying the RE.SIS.TO® method to the data collected from the 1st level CARTIS forms. In particular, a tree chart representation, characterized by variable number of branches depending on the different number of possible choices allowed by CARTIS form, is proposed for data organization of the typological-structural groups of buildings.

Development in Fuzzy Logic-Based Rapid Visual Screening Method for Seismic Vulnerability Assessment of Buildings

In order to prevent possible loss of life and property, existing building stocks need to be assessed before an impending earthquake. Beyond the examination of large building stocks, rapid evaluation methods are required because the evaluation of even one building utilizing detailed vulnerability assessment methods is computationally expensive. Rapid visual screening (RVS) methods are used to screen and classify existing buildings in large building stocks in earthquake-prone zones prior to or after a catastrophic earthquake. Buildings are assessed using RVS procedures that take into consideration the distinctive features (such as irregularity, construction year, construction quality, and soil type) of each building, which each need to be considered separately. Substantially, studies have been presented to enhance conventional RVS methods in terms of truly identifying building safety levels by using computer algorithms (such as machine learning, fuzzy logic, and neural networks). This study outlines the background research that was conducted in order to establish the parameters for the development of a fuzzy logic-based soft rapid visual screening (S-RVS) method as an alternative to conventional RVS methods. In this investigation, rules, membership functions, transformation values, and defuzzification procedures were established by examining the data of 40 unreinforced masonries (URM) buildings acquired as a consequence of the 2019 Albania earthquake in order to construct a fuzzy logic-based S-RVS method.

An improved rapid visual screening method for seismic vulnerability assessment of reinforced concrete buildings in Indian Himalayan region

An improved rapid visual screening method for seismic vulnerability assessment of reinforced concrete buildings in Indian Himalayan region

Seismic vulnerability assessment of old churches in the twin cities of Bhubaneswar and Cuttack using the macroelemental approach

Historic buildings are the cultural and traditional identity of a country. However, these buildings are vulnerable to earthquakes because of their aged structure, poor maintenance, and inadequate structural health monitoring. Therefore, seismic vulnerability assessment is a critical aspect in the restoration and retrofitting of heritage buildings. In this study, a comprehensive survey was performed to collect the data of old and historic church buildings in and around the twin cities of Bhubaneswar and Cuttack in Odisha for evaluating the performance of these structures against seismic activity. The macroelemental method for seismic vulnerability assessment was used to calculate the seismic vulnerability index of church buildings. The probable damage was estimated based on the obtained values of the mean damage grade according to the EMS-98 scale and were compared with the grade of damageability acquired using the rapid visual screening method for Indian conditions. Damage probability matrices were constructed to determine the probabilistic future damage. This study identified church buildings that require immediate renovation and retrofitting.

Seismic Damage Index Spectra Considering Site Acceleration Records: The Case Study of a Historical School in Kermanshah

The frequency content and time duration of earthquakes are as effective as the peak ground acceleration on structural damage. Therefore, using rapid seismic vulnerability assessment methods that consider the earthquake acceleration time history is noticeable. Kermanshah is a historical city that is generally affected by far-field earthquakes. Therefore, it is necessary to consider the effect of the low-frequency shocks in evaluating the vulnerability of buildings in this city. Herein, a historic school in Kermanshah is assumed as a case study and two well-known damage index formulas are used for determining the damage index spectra of this structure, considered as a single degree of freedom system. Then, the effective parameters of the damage index, including ductility, relative degradation of stiffness, and dissipated energy are determined from a nonlinear analysis of the structure under the effect of the most probable earthquake acceleration records. Finally, the damage index spectra can be used for rapid seismic vulnerability assessment of masonry buildings on similar sites with various fundamental periods for large-scale assessments. The result shows that the building tends to collapse at a peak ground acceleration of 0.15 g. Furthermore, results confirm the seismic resistance reduction effect of flexible floors.

Development of Intrinsic Seismic Vulnerability Index (ISVI) for assessing roadway system and its assets framework

Roadway systems and their assets are the backbone of the transport sector and are vital for social and economic prosperity. Hence, it is important to design and develop transportation networks that can withstand natural hazards such as earthquakes. In recent decades, research concerning disaster risk management for roadway systems has received a lot of attention, particularly via the use of seismic vulnerability assessment methods. The majority of those models focus on a single criterion e.g., physical degradation of road assets, traffic disturbance, and/or functionality loss of the network, rather than considering how different criteria interact, such as association between asset damage, functionality, and network traffic. The main purpose of this study is to provide an integrated methodology for evaluating the seismic vulnerability of road networks to inform decision-making for risk mitigation. The proposed framework correlates the Intrinsic Seismic Vulnerability Index (ISVI) scores with the variation of accessibility rates to critical service centers. The methodology is demonstrated through an application to a part of a road network for specific seismic scenarios. The ISVI quantifies the impact caused by a parameter's physical performance on the road behaviour using Non-Linear Dynamic Analysis (NLDA) technique, which can reduce or limit the role of the studies that are based on expert opinion decisions. The validated results shows that the embankment height is considered the most effective parameter in the physical assessment approach, followed by the number of lanes, while the soil type and pavement strength are the least effective parameters with a better effectiveness for soil type compared to pavement strength. Additionally, the integration between the physical assessment approach and the analysed accessibility rates is clearly showing compatibility between the vulnerability and accessibility approach, demonstrating more precise assessment tool by considering the correlation between the vulnerability rates and the reduced accessibility levels. The proposed approach can assist infrastructure owners and operators to reduce risk and boost emergency accessibility.• Conducting ISVI for roadway and its assets based on physical damage approach.• Assessing road networks accessibility rates by introducing an accessibility index (AI) using different geographical aspects.• Formulating an integrated model between physical damage and traffic accessibility through building transport performance maps.

PAIR COPULA TECHNIQUE OF SEISMIC VULNERABILITY ASSESSMENT OF CABLE-STAYED BRIDGE SYSTEM

As a high-order statically indeterminate structure, long-span cable-stayed bridges usually consist of many components such as main towers, stay cables, main beams, auxiliary piers, and connecting piers. Due to the mutual influence between components under earthquakes, the accurate simulations of the correlations among component seismic responses are critical to the vulnerability assessment of the overall system of a cable-stayed bridge. Pair Copula can simulate the correlation between two components. It is theoretically feasible to use Pair Copula in a hierarchically iterated way to simulate the whole system of a cable-stayed bridge. Therefore, a new seismic vulnerability assessment method of a cable-stayed bridge system is proposed based on Pair Copula iterative model. Based on structural uncertainty parameters and ground motion uncertainty, Latin hypercube sampling technique is used to establish bridge-ground motion probabilistic seismic response analysis samples. The correlations among the seismic responses of components are quantified through nonlinear dynamic time history and correlation analysis. Pair Copula models are fitted with maximum likelihood estimation and optimized based on AIC and BIC criteria. Through the hierarchical iteration of Pair Copulas, the overall model of a cable-stayed bridge is established, and its seismic vulnerability is evaluated. The engineering example shows that the correlation among multiple components can be accurately simulated based on the technology of hierarchical iteration of Pair Copula. With the assumption that the seismic responses of components are completely unrelated, the seismic vulnerability of a whole cable-stayed bridge system will be significantly overestimated.

Assessing Earthquake Impacts and Monitoring Resilience of Historic Areas: Methods for GIS Tools

Historic areas (HAs) are highly vulnerable to natural hazards, including earthquakes, that can cause severe damage, if not total destruction. This paper proposes methods that can be implemented through a geographical information system to assess earthquake-induced physical damages and the resulting impacts on the functions of HAs and to monitor their resilience. For the assessment of damages, making reference to the universally recognised procedure of convoluting hazard, exposure, and vulnerability, this paper proposes (a) a framework for assessing hazard maps of both real and end-user defined earthquakes; (b) a classification of the exposed elements of the built environment; and (c) an index-based seismic vulnerability assessment method for heritage buildings. Moving towards the continuous monitoring of resilience, an index-based assessment method is proposed to quantify how the functions of HAs recover over time. The implementation of the proposed methods in an ad hoc customized WebGIS Decision Support System, referred to as ARCH DSS, is demonstrated in this paper with reference to the historic area of Camerino-San Severino (Italy). Our conclusions show how ARCH DSS can inform and contribute to increasing awareness of the vulnerabilities of HAs and of the severity of the potential impacts, thus supporting effective decision making on mitigation strategies, post-disaster response, and build back better.

FEMA 310 Tier 1 seismic evaluation of existing building: A case study of a 7-story academic RC building of Jenderal Soedirman University, Indonesia

A need to predict the seismic vulnerability of current buildings has led to a heightened interest in study that deals with seismic vulnerability assessment methods. The easiest and fastest method, known as a walk-down survey or a street survey, involves just the superficial information accumulated during a short inspection of a building. This paper picks a fairly new seven-story academic building made of reinforced concrete (RC) located at the Jenderal Soedriman University in Purwokerto, Indonesia, which was designed in 2015 using construction details illustrative of that exact period, for FEMA 310 Tier 1 assessment in the context of Performance-Based Earthquake Engineering (PBEE). Mandatory checklists as a role of the region of seismicity and the building’s level of performance are done. The outcomes after a procedure projected the building in the case-study demonstrated a range of possible flaws and seismic vulnerability. Therefore, detailed comprehensive evaluation is intensely endorsed.

Simplified Seismic Vulnerability Assessment Methods: A Comparative Analysis with Reference to Regional School Building Stock in Italy

The paper compares several simplified methods proposed in the literature for assessing the seismic vulnerability of existing buildings. Type and number of input and output data, limitations of use for different structural typologies, and complexity of use are examined for each methodology to identify the most suitable for assessing the vulnerability of a given class of buildings, based on the available data, the computational effort, and the type of vulnerability judgment. The selected methods were applied to a sample of school buildings located in the province of Naples (Italy). Data were available due to a digital platform and were used to verify the possibility of providing reliable large scale vulnerability judgments based on a reduced set of information, without carrying out additional surveys. The most simplified methods were applied to a sample of about a thousand of buildings, while more detailed methods, needing more information, were applied to a smaller sample. The comparison between the results obtained from different methods allows highlighting advantages and weaknesses of each, so as to identify the convenience in their use according to the specific available information and the objectives of the analysis, finally to evaluate which is more or less safe.

An empirical method for seismic vulnerability assessment of Nepali school buildings

The 2015 Gorkha earthquake in Nepal damaged more than 28,000 school buildings across the affected areas. Nepali school buildings can broadly be categorized into special moment-resisting frame, brick masonry, stone masonry, timber, and composite construction (steel and masonry). This paper proposes a new methodology to designate seismic vulnerability of these building categories. The proposed methodology is based on the field study of around 3389 school buildings in central Nepal. Structural, non-structural, architectural, site conditions, seismic enhancement and retrofitting, and multi-hazard parameters are incorporated to develop a scoring system. Indexed based system is introduced using sensitivity analysis which allows the designation of total vulnerability scores to individual buildings. The scores are modified based on the level of seismic strengthening/retrofitting. Based on the total vulnerability score, a qualitative vulnerability level is assigned to the individual building. The results highlight that more than 90% of Nepali school buildings are moderate to very highly vulnerable.

Seismic Vulnerability Assessment of Historic Constructions in the Downtown of Mexico City

Seismic risk is determined by the sum of multiple components produced by a certain seismic intensity, being represented by the seismic hazard, the structural vulnerability and the exposure of assets at a specified zone. Most of the methods and strategies applied to evaluate the vulnerability of historic constructions are specialized in buildings with higher importance, either public or private, by relegating ordinary dwellings to a second plane. On account of this, this paper aims to present a seismic vulnerability assessment, considering a limited urban area of the Historic Downtown of Mexico City (La Merced Neighborhood), thus showing the analysis of 166 historic buildings. The seismic vulnerability assessment of the area was performed resorting to a simplified seismic vulnerability assessment method, composed of both qualitative and quantitative parameters. To better manage and analyze the human and economic exposure, the results were integrated into a Geographic Information System (GIS) tool, which allowed to map vulnerability and damage scenarios for different earthquake intensities.

Seismic damage scenarios for the Historic City Center of Leiria, Portugal: Analysis of the impact of different seismic retrofitting strategies on emergency planning

As a result of several impactful events, the focus of the international community on the effects of natural hazards in urban areas has been increasing in recent years. The framework for research and innovation on urban risk reduction and urban resilience is presently defined by several technical and societal challenges at different levels. In fact, urban risk is a very complex multi-dimensional matrix that can involve multiple elements at risk, multiple hazards, multiple temporal scales, and multiple sources of vulnerability. Understanding the impacts and interactions between these elements is an essential step towards the development of more effective risk reduction strategies, particularly in historical city centers, which, due to their characteristics, are even more demanding. Within this framework, the present paper takes advantage of a large-scale seismic vulnerability assessment method, specially developed to assess the vulnerability of masonry façade walls, to evaluate the vulnerability and to develop damage scenarios for the Historic City Center of Leiria. Based on these scenarios, obtained for the relevant seismic intensities of the region, a variety of probabilistic-based outputs related to emergency planning (inaccessible urban areas, isolated people, and possible evacuation routes) were generated and comprehensively discussed. Finally, the potential benefit resulting from the application of different seismic retrofitting strategies is also investigated, both in terms of expected damages and evacuation scenarios.

Development of a Numerical Tool for the Seismic Vulnerability Assessment of Vernacular Architecture

ABSTRACT Aiming at protecting the vernacular heritage located in earthquake prone areas, the paper presents the development and validation of the numerical tool that constitutes the core of a novel seismic vulnerability assessment method: Seismic Assessment of the Vulnerability of Vernacular Architecture Structures (SAVVAS). An extensive numerical modeling campaign was carried out to evaluate and quantify the influence of several parameters on the seismic response of vernacular buildings. The results were compiled into a database on which regression analysis could be performed to extract correlations between seismic capacity and qualitative and simple quantitative data that can be obtained from visual inspection.

Use of post-earthquake damage data to calibrate, validate and compare two seismic vulnerability assessment methods for vernacular architecture

The paper presents and discusses the application of two large scale seismic vulnerability assessment methods on the island of Faial in Azores (Portugal). The two methods are specifically conceived to assess the seismic vulnerability of vernacular architecture. The first method follows a classical seismic vulnerability index approach and is referred as SVIVA (Seismic Vulnerability Index for Vernacular Architecture). The second method is referred as SAVVAS (Seismic Assessment of the Vulnerability of Vernacular Architecture Structures) and it is a numerical tool intended to estimate the seismic capacity of vernacular buildings in terms of seismic load factors associated with different structural damage limit states. The main reason behind the selection of Faial Island as a case study was the availability of post-earthquake reports of the building stock after the 1998 Azores earthquake, which allowed comparing the damage scenarios obtained using both methods with the post-earthquake damage data and thus helped for the calibration and validation of the two methods. The application of both methods led to a good fit between estimated versus observed damage grades, which validated their applicability as large-scale first level approaches. Moreover, as the main outcome, the paper presents the novelties of the SAVVAS method, which had not been applied before, and discusses its main advantages, namely: no need for calibration with previous post-earthquake damage data, an enhancement of the prediction capabilities, a more individualized evaluation of the buildings and the possibility to assess the seismic performance of the building in different loading directions.

Assessing seismic vulnerability of urban road networks by a Bayesian network approach

Evaluating the seismic vulnerability of urban road network is important for proactive reinforcement of the weakest link of the road network and post-disaster response and recovery of infrastructure systems. The paper proposes a Bayesian network (BN) method for seismic vulnerability assessment of an urban road network considering spatial seismic hazard with different levels of ground motion intensities, vulnerability of the components and effect of structural damage of components within the road network to the network functionality.Seismic vulnerability of the components in the road network is quantified based on physical structural damage under the earthquake demand. The vulnerability of the network is evaluated in terms of its dis-connectivity due to structural damage and induced transportation functional loss. BN model is built with vulnerability of the components as prior probability. The BN structure and CPT (Conditional Probability Table) is established based on transportation network analysis. The dis-connectivity of the road network is updated in light of information obtained from the observation of system or component states. Thus, the posterior probability could be calculated to identify the critical links and assess the seismic vulnerability of road network respectively. A case study is presented to show the application of the method. Results may contribute to the decision making on the reinforcement of the road network and the management of available resources to improve the disaster resilience and functionality of transportation systems in terms of seismic vulnerability.

A Detailed Comparison of Preliminary Seismic Vulnerability Assessment Methods for RC Buildings

Tier 2 (preliminary) evaluation methods seem to be efficient in determining seismic vulnerability of buildings in large building stocks because they can be used to determine the seismic performance of a single building when compared to Tier 1 evaluation methods (street survey). Besides, they require less time as opposed to detailed evaluation methods (Tier 3). Eleven preliminary vulnerability analysis procedures are compared considering the data of 192 buildings experienced either 2011 Van Earthquakes, 2003 Bingol Earthquake or 2002 Afyon Earthquake. Comparisons are made in terms of the number of parameters, influence of parameters on final seismic score, weighing factors of the parameters, the success rate of predicting the seismic performance of the examined buildings. Investigated procedures use at least four parameters and at most 22 parameters. Although number of stories have adverse effect on the seismic performance, concrete strength, area of shear walls and columns seem to have positive effect. Among the main parameters used in all procedures, area of shear walls is found to be the most influential parameter; however, concrete strength is one of the least effective parameters. As for the rate of correct vulnerability estimate of the 192 buildings, it is found that the best prediction rate belongs to Sucuoglu and Yazgan (in Wasti and Ozcebe (eds) Seismic assessment and rehabilitation of existing buildings, NATO science series (series IV: earth and environmental sciences), Kluwer Academic Publishers, London, 2003) with 79.2%. All the procedures except Ozcebe et al. (in Wasti and Ozcebe (eds) Seismic assessment and rehabilitation of existing buildings, NATO science series (series IV: earth and environmental sciences), Kluwer Academic Publishers, London, 2003) have correct estimate rate equal to or higher than 63%.

Seismic vulnerability classification of roads

Experience from past earthquakes all over the world showed that the road network could undergo heavy damages. To prevent these damages, vulnerability studies must be carried out.The purpose of this study is to develop a seismic vulnerability assessment method for roads. The methodology is based on determination of a numerical indicator called Vulnerability Index (VI). To achieve this, the main parameters that influence the seismic behaviour of roads are identified on the basis of the worldwide seismic feedback experience and data from past Algerian earthquakes. Furthermore, the Analytical Hierarchy Process (AHP) is used to quantify the identified parameters and define an analytical expression of the ‘VI’. A classification of the seismic vulnerability of road sections is proposed, according to the obtained Vulnerability Index (VI) value.To exhibit the efficiency of the developed method, several road sections are studied and the obtained results are in good adequacy with in-situ observations. Moreover, in order to assess the seismic vulnerability of an urban city road network, the developed model is combined to a GIS (Geographical Information System) to perform several earthquake scenarios and the results of Tipaza city are presented.