Methodology For Seismic Vulnerability Assessment Research Articles

Exposure and physical vulnerability indicators to assess seismic risk in urban areas: a step towards a multi-hazard risk analysis

Understanding the impacts of multi-hazard risk in urban areas is a fundamental step towards the adoption of resilience-enhancement and disaster prevention strategies, underpinning institutional adjustments aimed at improving the capacity of the authorities and stakeholders to manage risk. Within this framework, the work presented in this paper seeks to identify and analyze a set of exposure and buildings’ physical vulnerability indicators to be used as input to a parametric-based seismic vulnerability assessment methodology for the unreinforced masonry (URM) building stock of Lisbon Metropolitan Area (LMA). For this approach, data from the 2011 Census survey are used to define the parameters describing the building’s physical vulnerability and characterise the level of exposure in the study area. These results are then combined with the hazard component into a GIS tool. Seismic vulnerability results are presented for the URM building stock in LMA, and a more detailed analysis is conducted for the building stock of Setúbal municipality. Finally, risk outputs are presented and briefly discussed. Ultimately, understanding the impact and extent of multi-hazards can help prioritize resilience-increasing actions and disaster prevention measures to mitigate and manage natural hazards.

Improved Component-Level Deterioration Modeling and Capacity Estimation for Seismic Fragility Assessment of Highway Bridges

AbstractThis paper presents a novel vector-based seismic vulnerability assessment methodology for deteriorating highway bridges by uniquely accounting for realistic deterioration of key structural ...

Assessing the Vulnerability of Kota Kinabalu Buildings

A gradual increase in moderate and low seismic activity has occurred in Sabah over the course of several years due to the presence of certain moderately active fault lines in the region. Around 300 moderate earthquakes with magnitudes ranging from MW 4.0 to 7.0 have occurred in the last 120 years. The majority of existing buildings in Sabah are wind and gravity loaded. This study proposes a preliminary seismic vulnerability assessment methodology based on empirical and analytical vulnerability method for 250 existing buildings in Kota Kinabalu city. The empirical vulnerability assessment focuses on building evaluation utilizing a standard Rapid Visual Screening (RVS) method and the FEMA 154 guidebook's moderate seismicity assessment form. A field survey was conducted on the buildings ranging in height from low-rise to high-rise. As a result, when subjected to moderate-intensity earthquakes, 60% of the buildings are classed as susceptible and vulnerable to seismic hazard. The current study included the use of nonlinear static analysis to seven different building cases for further investigation. The findings of the analysis demonstrate that the majority of the buildings respond linearly elastical when subjected to peak ground acceleration (PGA) at 0.17g, which indicate that, buildings without seismic design accumulate damage early when subjected to moderate earthquake loadings.

Database Enabled Rapid Seismic Vulnerability Assessment of Bridges

As the seismic hazard has been updated for the central U.S., state Departments of Transportation (DOTs) find an increasing need to assess the seismic vulnerability of their bridge network. Traditional methods to perform seismic assessment require developing dynamic models for each bridge. However, this approach requires specialized engineering knowledge and information from structural drawings, and is time-consuming. To streamline this important task, a simplified dynamic modeling procedure is described that leverages readily available information from DOTs’ asset management databases. With a minimal amount of additional data items, the asset management database can be used to identify vulnerable bridges rapidly and with sufficient accuracy for the prioritization of retrofit decisions. A detailed analysis of a 100-bridge sample set identified typical vulnerabilities and established corresponding capacity thresholds. The rapid seismic vulnerability assessment methodology is implemented as an Excel macro-enabled tool for bridge owners and asset managers to rapidly assess the vulnerability of each individual bridge based on current information in the database, and then classify the vulnerability of each individual bridge as low, medium, or high. Current DOT databases used for asset management in regions of low-to-moderate seismicity do require some data items be added for a robust assessment. These data items are identified here and leveraged to demonstrate the method. The rapid assessment methodology presented can be implemented to effectively identify the most vulnerable bridges in a bridge network, thus facilitating a rapid state bridge inventory network assessment to prioritize and inform actions such as maintenance and rehabilitation.

Seismic vulnerability assessment methodology for historic masonry buildings in the near-field areas

Timisoara is the biggest city located in the Banat seismic area, the second most important seismic zone of Romania. The specificity of the area is represented by shallow earthquakes of crustal type, with small focal depths and a PGA = 0.20 g.Because Timisoara was declared the European Capital of Culture 2021, it is mandatory to assess the seismic vulnerability of its most sensitive areas and to design potential losses scenario. This study also provides useful data for the local authorities, helping them develop/improve the prevention and intervention plans.The paper focusses on the analysis of two historical urban districts, likely to be among the most attractive tourist areas. The study aims to assess the seismic vulnerability of the districts in a quick and simplified way, seeks to identify the exposure of the city, and also to provide losses statistics for a specific seismic scenario. The empirical seismic vulnerability assessment methodology is based on European studies and is applied for more than 100 historic buildings.Our assessment analysis aims to adapt the existing seismic assessment methodologies to the near-field earthquake’s effects. That is why a new formula is proposed to correlate the empirical vulnerability curves with the actual damage level. The real damage state was observed on similar historical masonry buildings during the site inspection and after the past earthquakes in nearby areas. Besides, a new failure mechanism is highlighted based on the investigation of the effects of previous near-field earthquakes in the Banat seismic region. The new methodology proposes original vulnerability curves, particularly for the near-field earthquakes specific to Banat seismic area.

The use of Artificial Neural Networks to estimate seismic damage and derive vulnerability functions for traditional masonry

This paper discusses the adoption of Artificial Intelligence-based techniques to estimate seismic damage, not with the goal of replacing existing approaches, but as a mean to improve the precision of empirical methods. For such, damage data collected in the aftermath of the 1998 Azores earthquake (Portugal) is used to develop a comparative analysis between damage grades obtained resorting to a classic damage formulation and an innovative approach based on Artificial Neural Networks (ANNs). The analysis is carried out on the basis of a vulnerability index computed with a hybrid seismic vulnerability assessment methodology, which is subsequently used as input to both approaches. The results obtained are then compared with real post-earthquake damage observation and critically discussed taking into account the level of adjustment achieved by each approach. Finally, a computer routine that uses the ANN as an approximation function is developed and applied to derive a new vulnerability curve expression. In general terms, the ANN developed in this study allowed to obtain much better approximations than those achieved with the original vulnerability approach, which has revealed to be quite non-conservative. Similarly, the proposed vulnerability curve expression was found to provide a more accurate damage prediction than the traditional analytical expressions.

Seismic vulnerability assessment of churches at regional scale after the 2009 L'Aquila earthquake

The extension of damage on churches observed after strong earthquakes stresses the need to define suitable speedy methods for the assessment of the main sources of structural fragility for these constructions. This paper presents a methodology for seismic vulnerability assessment of churches based on a damage reconnaissance activity carried out after the 2009 L'Aquila earthquake on a population of 64 churches. Firstly, the post-earthquake evaluation of damage is described aiming at identifying recurrent damage mechanisms. It has been observed that the occurred damage scenario, shown through damage probability matrixes, can be represented by a binomial distribution, which depends only on mean damage level. Then, a literature predictive model is applied for outlining fragility curves, which represent a useful tool for prediction of likely damage scenarios. Finally, some ongoing applications of the proposed analysis methodology to churches of different territorial areas are described.

Seismic vulnerability assessment methodology for slender masonry structures

ABSTRACTSlender masonry structures such as towers, minarets, chimneys, and Pagoda temples can be characterized by their distinguished architectural characteristics, age of construction, and original function, but their comparable geometric and structural ratios yield to the definition of an autonomous structural type. These structures constitute a part of the architectural and cultural heritage. Their protection against earthquakes is of great importance. This concern arises from the strong damage or complete loss suffered by these structures during past earthquakes. Seismic vulnerability assessment is an issue of most importance at present time and is a concept widely used in works related to the protection of buildings. However, there is few research works carried out on developing the seismic vulnerability assessment tools for such structures.This article presents a new method for assessing the seismic vulnerability of slender masonry structures based on vulnerability index evaluation method. The calculated vulnerability index can then be used to estimate structural damage after a specified intensity of a seismic event. Here, 12 parameters are defined to evaluate the vulnerability index for slender masonry structures. Implementation of this methodology is carried out in different types of slender masonry structures to develop vulnerability curves for these structure types.

The Use of a Large-Scale Seismic Vulnerability Assessment Approach for Masonry Façade Walls as an Effective Tool for Evaluating, Managing and Mitigating Seismic Risk in Historical Centers

ABSTRACTThe vulnerability assessment of the building stock in a given territorial area, such as a city or an entire country, is a key prerequisite for evaluating risk, not only because of the potential physical consequences resulting from the occurrence of an event, but also because it is one of the few aspects in which engineering research can intervene. In fact, the rigorous vulnerability assessment of existing buildings followed by the implementation of appropriate retrofitting solutions can help to substantially reduce the levels of physical damage and economic impact of future events. Particularly regarding the seismic vulnerability assessment of historical centers, the amount of knowledge that has been accumulated over the past decades, together with the broad damage data obtained from post-earthquake damage surveys, provides a singular opportunity to develop and calibrate innovative large-scale seismic vulnerability assessment approaches, which can be used to outline and support risk mitigation and management strategies. This article addresses this issue by discussing the use of a large-scale seismic vulnerability assessment methodology for masonry façade walls as a tool for evaluating the potential benefit resulting from the application of different seismic retrofitting strategies, both considering their contribution to reduce post-event urban losses and accessibility.

Spectral Functions of Damage Index (DI) for Masonry Buildings with Flexible Floors

Most of the buildings in old city cores of Croatia, built between 1860 and 1920 with wooden floors, are mainly designed to bear vertical loads. In this paper we propose a methodology for seismic vulnerability assessment of unreinforced masonry buildings with flexible floors. The methodology is based on the calculation of Damage Index (DI), a numerical value indicating the level of structural damage. In this methodology, the structure is represented using an SDOF model determined by damping, weight, elastic base shear capacity, elastic stiffness and post-elastic stiffness. Using accelerograms of earthquakes, step by step time-history numerical integrations are provided along with the results: top displacement, yield excursions, cumulative energy and base shear–displacement. These results serve as parameters which are then input in the formula for Damage Index (DI). The results of the paper are presented in the form of diagrams with DI values on the y axis and fundamental period of the structure on the x axis. These spectral functions of DI, along with knowledge of fundamental period and chosen accelerogram, can be used to quickly determine the level of damage for unreinforced masonry buildings with flexible floors.

Urban-scale seismic fragility assessment of RC buildings subjected to L'Aquila earthquake

A damage scenario on a database of Reinforced Concrete (RC) buildings subjected to the 6th April 2009 L'Aquila earthquake is derived from the application of the POST (PushOver on Shear Type models) procedure, a simplified analytical methodology for seismic vulnerability assessment of RC buildings at large scale.Based on the simplified assumption of shear type modelling, POST methodology allows the derivation of the non-linear static behaviour of RC buildings accounting for the influence of infill panels. The seismic capacity is evaluated in terms of spectral intensity measures at different Damage States (DSs) based on the displacement capacity of structural and non-structural elements. DSs and the corresponding displacement thresholds are defined through the interpretation of the observational-based DSs provided by the European Macroseismic Scale EMS-98. Finally, a seismic fragility assessment is carried out, introducing random variables and adopting a Monte Carlo simulation technique.A database of 250 RC buildings located in the Municipality of L’Aquila is considered. The predicted damage scenario is compared with the observed post-earthquake damage collected from post-earthquake emergency survey forms. The influence of certain parameters on the derivation of damage scenarios is investigated, namely the assumptions made regarding the distribution of infill panels within the analysed buildings (i.e., internal partitions) and on spectral shape.The reliability of the adopted simplified analytical procedure and of the assumed mechanical interpretation of damage classification of EMS-98 are validated through the comparison of the predicted and observed percentage of buildings in each DS and distributions of damage to structural components (vertical structures and infill panels).

The development of a seismic vulnerability assessment methodology for contemporary loadbearing masonry buildings in the Maltese Islands

This study focuses on the development of a seismic vulnerability assessment method adapted for use on the contemporary loadbearing masonry building typology present in the Maltese Islands. This assessment methodology refers to existing vulnerability assessment methodologies, preand post-earthquake survey methods and manuals developed for different Italian regions. The methodology refers to seismic vulnerability characteristics present in the building typology under study. The method was tested in a pilot study in Msida and then in the test sites of Xemxija and Nadur covering 183 individual buildings. The assessment was carried out through site surveys and information extracted from the Development Permit Drawings. FEMA 154 and a GNDT level II seismic vulnerability evaluation were carried out to assess the differences between the methods when these are applied to the typology analysed and also to assess the merits of the proposed new method developed for the Maltese Islands.

Seismic Resistance Assessment of Heritage Masonry Buildings in Ljubljana

A recently developed parametric method (PO-ZID) for the assessment of the seismic resistance of masonry buildings is presented, with an estimate of the correlation of this approach with the latest Slovenian methodology for seismic vulnerability assessment (RAN-Z). The acronyms PO-ZID and RAN-Z refer, in Slovenian, to the seismic resistance and seismic vulnerability of masonry buildings. The new method is based on a well-considered choice of parameters and a suitable database. The input parameters are determined on the basis of the known mechanical properties of masonry, the amount and distribution of the structural walls, and the weight of the building. The only output parameter is the seismic resistance coefficient, which is the ratio between the seismic resistance and the weight of the building. The database has been assembled from the results of the seismic resistance analysis of existing buildings, mainly heritage masonry buildings, located in the Municipality of Ljubljana, as well as in other parts of Slovenia. This new method was applied to several groups of older masonry buildings, many of which are in public use, such as fire stations, older elementary school buildings and kindergartens, and some buildings belonging to local or national authorities.

Vulnerability assessment and earthquake damage scenarios of the building stock of Potenza (Southern Italy) using Italian and Greek methodologies

The prevailing Italian and Greek methodologies for seismic risk assessment are used herein to construct loss scenarios for the building stock of a small city (Potenza, Southern Italy). The inventory of buildings of interest is obtained from a survey carried out after the 1990 earthquake that struck Potenza and its hinterland, subsequently updated in 1999. About 12,000 buildings were surveyed in Potenza, using the Italian first level survey form for damage and vulnerability evaluation. In the Italian methodology, a hybrid technique is set up to evaluate vulnerability, combining an analysis of building typologies with expert judgement. The probabilistic distribution of damage is evaluated by assigning Damage Probability Matrices (DPMs) from the literature. Besides the vulnerability classes A, B and C of the MSK-scale, the class D of the anti-seismic buildings is considered and the relevant DPM is defined. Damage and economic loss scenarios relevant to dwelling buildings are constructed for three reference earthquakes. Next, the hybrid methodology for seismic vulnerability assessment of reinforced concrete (R/C) and masonry buildings developed at the University of Thessaloniki (Greece) is applied to the same building stock. The methodology combines available statistical data of damage collected after past earthquakes with a systematic nonlinear analysis of various “model buildings”, representative of several vulnerability classes. Similarities, as well as discrepancies, between the two methods are discussed in the light of the obtained results, and possible sources for the discrepancies are suggested.