Vulnerability Assessment Of Masonry Buildings Research Articles

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.

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.

Seismic vulnerability assessment of masonry buildings in Karachi

Seismic vulnerability assessment of masonry buildings in Karachi

On the Use of Web Mapping Platforms to Support the Seismic Vulnerability Assessment of Old Urban Areas

European countries are affected by various levels of seismic hazard, including many areas with medium to high seismicity. Heavy damage over large areas has been observed in past earthquakes in these countries, particularly in masonry buildings located in historical centers, confirming the need for enhancing the current knowledge on the seismic vulnerability of these constructions, so more informed technical and political decisions towards the mitigation of the risk can be taken. However, the characterization of building stocks for engineering purposes is still an open issue due to the enormous amount of resources that such a project would require. Nevertheless, the availability of virtual images and maps represents an outstanding opportunity for having remote approaches to urban environments. The role of on-site inspections can be complemented or even substituted by means of these remote approaches, provided it is complemented with suitable approaches. The use of these resources is not new, but the critical assessment of their capabilities and limitations deserves a critical discussion. The present paper aims at assessing the opportunities offered by web-based mapping platforms in the context of seismic vulnerability assessment of masonry buildings in old urban areas. After evaluating the advantages and shortcomings of some of the most popular web-based mapping services, an explanatory application to a set of 39 buildings located in the historic center of the city of Leiria (Portugal) is presented and critically discussed, contrasting the results obtained by using on-site and remote inspections. Two different seismic vulnerability assessment approaches are applied and analyzed herein, confirming that web-based mapping platforms can represent an efficient and cost-effective complement to traditional field surveys when the large-scale seismic vulnerability of old urban areas is of interest.

Fragility curves for Italian URM buildings based on a hybrid method

A hybrid seismic fragility model for territorial-scale seismic vulnerability assessment of masonry buildings is developed and presented in this paper. The method combines expert-judgment and mechanical approaches to derive typological fragility curves for Italian residential masonry building stock. The first classifies Italian masonry buildings in five different typological classes as function of age of construction, structural typology, and seismic behaviour and damaging of buildings observed following the most severe earthquakes occurred in Italy. The second, based on numerical analyses results conducted on building prototypes, provides all the parameters necessary for developing fragility functions. Peak-Ground Acceleration (PGA) at Ultimate Limit State attainable by each building’s class has been chosen as an Intensity Measure to represent fragility curves: three types of curve have been developed, each referred to mean, maximum and minimum value of PGAs defined for each building class. To represent the expected damage scenario for increasing earthquake intensities, a correlation between PGAs and Mercalli-Cancani-Sieber macroseismic intensity scale has been used and the corresponding fragility curves developed. Results show that the proposed building’s classes are representative of the Italian masonry building stock and that fragility curves are effective for predicting both seismic vulnerability and expected damage scenarios for seismic-prone areas. Finally, the fragility curves have been compared with empirical curves obtained through a macroseismic approach on Italian masonry buildings available in literature, underlining the differences between the methods.

GIS-Based Assessment of Seismic Vulnerability Information of Old Masonry Buildings Using a Mobile Data Validation System

AbstractThis study proposes a geographic information system (GIS)–based rapid visual screening approach for seismic vulnerability assessment of masonry buildings in culturally and architecturally i...

Seismic vulnerability assessment of masonry buildings in Banja Luka and Sarajevo (Bosnia and Herzegovina) using the macroseismic model

Assessment of seismic vulnerability in urban areas is a challenging task that requires a meticulous and systematic approach. Sarajevo and Banja Luka, together with Tuzla, are the most urbanized and densely populated cities in Bosnia and Herzegovina. Sarajevo and Banja Luka experienced devastating earthquakes in 1962 and 1969, respectively. This is why it is of the utmost importance to conduct seismic vulnerability evaluation of the existing building stock in Bosnia and Herzegovina. Until today no systematic database regarding structures and their typology has been compiled for the territory of Bosnia and Herzegovina in connection with their vulnerability to seismic actions. The choice of an appropriate vulnerability method plays a key role in the process of assessment of seismic risk and highly depends on the available information, characteristics of the buildings, organization of data collection and decision-makers. Among various methods, it was decided to use the macroseismic method derived from the EMS-98 scale for the vulnerability assessment of the existing buildings in Bosnia and Herzegovina. The database was obtained from the “typology of residential buildings in the BiH” project, a comprehensive survey of 13,044 existing residential buildings in BIH, which was conducted for energy performance assessment of the national building stock. For the purpose of this research, the database was reduced to a sample of 2933 buildings, as it included a selection of only unreinforced and confined masonry buildings built from 1918 to 2014 and located in Sarajevo and Banja Luka. The aim of this paper is to provide an overture in assessing the seismic risk in Sarajevo and Banja Luka by applying the method based on the vulnerability index. The vulnerability index is calculated by the macroseismic method which is in the function of the type of building, regional vulnerability factor and behavior modifier factors. The application of this method confirms the notable seismic risk in the cities of Sarajevo and Banja Luka due to the high vulnerability of the buildings. It may be argued that the behavior modifiers which had the largest impact on the change of the vulnerability class were the number of floors and type of roof structure. This research intends to contribute to the prevention of an earthquake disaster, in the form of a theoretical forecast of the aftermath: structural damage and/or socio-economic losses that may occur after an earthquake.

Seismic vulnerability of URM structures based on a Discrete Macro-Element Modeling (DMEM) approach

The assessment of the seismic vulnerability of unreinforced masonry (URM) structures based on numerical modeling constitutes a difficult task due to their complex behavior, especially in the nonlinear dynamic field, and the lack of suitable, low-demanding, computational tools. In the last decades, practical statistical tools for the derivation of fragility curves have been successfully proposed mainly with reference to framed structures. This approach has been adopted also for the seismic vulnerability assessment of masonry buildings focusing on the in-plane collapse mechanisms by means of equivalent frame models. Nevertheless, the lack of computationally effective tools which involve the interaction between in-plane and out-of-plane mechanisms makes the definition of fragility curves an arduous task when it comes to existing masonry structures without box behavior.In this paper, a practical and thorough methodology for the assessment of the seismic vulnerability of URM buildings by means of analytical fragility curves is presented. This methodology presents some innovative features such as the definition of the Limit States (LSs) and their corresponding capacity based on multi-directional pushover analyses, as well as the application of nonlinear dynamic analyses, performed using a discrete macro-element modelling approach capable of simulating the main in-plane and out-of-plane responses of URM structures with a reduced computational burden. The present investigation focuses on the application of this methodology for assessing the seismic vulnerability of a brick masonry structure characterized by a strong out-of-plane failure mechanism. After a fitting process, the fragility curves were compared to the ones obtained using expert-based approaches.

Performances of FRP reinforcements on masonry buildings evaluated by fragility curves

The seismic vulnerability assessment of masonry buildings reinforced with FRP was investigated by means of random sampling of their mechanical properties and repeated nonlinear static analyses. To this aim, the Monte Carlo simulation method was adopted to account for the uncertainty of the mechanical parameters characterizing the analytical model representative of each structural prototype. In particular, a two-step procedure was proposed. First, to ensure an appropriate calibration of the model, was investigated the mechanical behavior of two case-studies structures: an unreinforced masonry panel and a masonry panel externally reinforced with FRP composite strips applied with a grid configuration and anchored properly at their ends. Then, the effectiveness of a FRP reinforcement designed for the main façade of the historical Camponeschi Palace (located in the city of L’Aquila, Italy) was estimated. The proposed methodology was used to determine the probability of occurrence of several damage states and to estimate the relevant probability density functions corresponding to different levels of ground motion. The novelties of the modeling procedure proposed, together with the benefits provided by the FRP reinforcement, were presented and discussed in detail.

Damage Functions for the Vulnerability Assessment of Masonry Buildings Subjected to Tunneling

This paper describes a new framework for the assessment of potential damage caused by tunneling-induced settlement to surface masonry buildings. Finite element models in two and three dimensions, validated through comparison with experimental results and field observations, are used to investigate the main factors governing the structural response to settlement. Parametric analyses are performed on the effect of geometrical and structural features, like the building dimensions, the nonlinear behavior of masonry, and soil-structure interactions. These results are used to create a framework of an overall damage model that correlates the analyzed parameters with the risk of the building being damaged by a given level of settlement. The proposed vulnerability framework has the potential to be developed as a decision and management tool for the evaluation of the risk associated with underground excavations in urban areas.

Seismic vulnerability assessment of historical urban centres: case study of the old city centre in Seixal, Portugal

The seismic vulnerability assessment of old masonry buildings is essential not only to buildings with recognised historical and heritage value but also to ordinary residential masonry buildings. This paper approaches the seismic vulnerability assessment of masonry buildings by applying a simplified methodology to the old city centre of Seixal in Portugal. The methodology adopted in this study was based on a vulnerability index used for the evaluation of damage and the study of loss scenarios on a large scale. Over 500 buildings were assessed using this methodology, and the results were analysed using an integrated Geographical Information System tool. The integration of the vulnerability and loss results could allow city councils or regional authorities to plan interventions based on a global view of the site under analysis, leading to more accurate and comprehensive risk mitigation strategies that support the requirements of safety and emergency planning.

Seismic vulnerability assessment of masonry buildings in a region of moderate seismicity

To assess the seismic vulnerability of masonry buildings is largely matter of personal feeling and experience especially when dealing with old houses made of heterogeneous materials and without a plan. One way to predict their resistance to earthquake forces is the experience on models put on a shaking table. Costs and scaling problems, particularly severe for stone walls, are limiting factors in the extensive use of this technique. After the Friuli 1976 earthquake, the regional government arranged a detailed survey of damages suffered by buildings to be repaired. These data organised in the FRED (Friuli Earthquake Database) make it possible to compare, on a statistically significant basis, the a priori vulnerability with the effective damage. One further step towards the practical use of the results is given by characterising the relevant features of the buildings with the same parameters which can be found in the General Census periodically produced by the Italian Statistical Institute (ISTAT).

A Knowledge‐Based System for Seismic Vulnerability Assessment of Masonry Buildings

Abstract: A specific class of structures, masonary, is considered. For its analysis a great expertise is available. The ‘state of health’ of a single existing building is assissed by an expert system which incorporates this expertise. The paper illustrates a knowledge‐based expert system for the seismic vulneraility assesment of masonry buildings.