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Seismic Risk Map in MATLAB

One of the main goals of STABLE project is the development of a platform that will address seismic risk for cultural heritage sites at a medium scale (block of buildings and large structures) in order to derive damage maps before the occurrence of a seismic event and define the areas of maximum probable loss. Towards the development of the platform, a MATLAB code is written that calculates the risk map of the building stoke of an area for a given seismic hazard by applying a simplified mechanical method. The risk is defined as the probability of a certain level of damage to be exceeded. Four different levels of damage are examined, namely P1, P2, P3 and P4. The level of damage Pi increases with increasing i = 1 to 4. The probability takes values from zero (totally unlikely) to one (certainty). The input data include:

  • Information regarding the structures (geometrical data, exact coordinates, typology)
  • Information regarding the seismic hazard in the examined area (seismic acceleration) resulted from a seismic hazard analysis taking into account the seismic sources and the local soil effect

The code provides as results the four seismic risk maps that correspond to the four different levels of damage. Every figure depicts with color the value of probability Pi for the given seismic hazard. The results are also provided in a txt output file while the original structural shapefile are also updated based on the results.

Output of the MATLAB code

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CITY CENTRE IN STROVOLOS, NAFPLIO AND RIETI: SEISMIC MOVEMENTS IMPACTING ON THE BUILDINGS

Three cases study to define a new approch to protect the city centre and Cultural Heritage from earthquake damage. In STABLE project (co-funded by the European Commission, carried out in the context of the HORIZON 2020 program supervised by EU Authority) consortium members focusing the attention on monitoring methods.

Keyword: Cultural Heritage, European project, Historical Centres

 

The cases study of Rieti (Italy), Strovolos (Cyprus) and Nauplion (Greece) are choosen for their specific geological characteristics and for their historical interest, but at the same time for their position, in a trait high seismic risk areas.  

In order to reach a seismic hazard assessment, the study of the sites followed specific steps:

  • description of the plate tectonics regime, faults and studies of their movements,
  • historical seismicity of the area,
  • seismic sources (models of the faults recognised in the area of interest). The modelling has been performed cautiously, taking into consideration all available geological, seismological, and geophysical data,
  • seismic microzonation mapping, a synthesis of data obtained from in-situ tests, detailed surveys, historical damage reports, etc. incorporating investigations at different scales.

To calculate the synthetic accelerograms for the regions, were initially conducted probabilistic seismic hazard analysis, then were calculated synthetic acceleration time series using the stochastic simulation methodology, getting the deterministic seismic hazard assessment by using specific software. Then all the information gathered will be processed in the open source GIS software QGis.

At the end will be achieved the seismic analysis of the different cases study, the time histories, that will be accesible, viewable inside a dadicated WebGis platform, like all the rest of the documentation (primary and secondary) data used and producted inside the project by the partners of the consortium.

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SEISMIC MOVEMENTS IMPACTING ON THE STRUCTURAL STABILITY OF THE CULTURAL HERITAGE

Generation of risk maps and structural stability model assessment are fundamental to prevent earthquake damage on Cultural Heritage. Earthquake simulation with different intensities will be used to assess the assessment regarding expected damage on monuments and city center.

Keyword: Cultural Heritage, European project, Historical Centers

The STABLE (STructural stABiLity risk assEssment) project attempts to address seismic risk maps on Cultural Heritage (CH) at medium scale and introduce a new strategy, by selecting the most efficient methods and tools for data harmonization as well as criteria and indicators for tracking of impact of environmental changes on tangible cultural heritage assets.

To achieve this goal, it is necessary to design and develop an IT service platform, that combine advanced satellite technologies with existing ground-based data and risk forecasting modelling. This enables a continuous long-term monitoring and update of structural stability of the architectural heritage and the historical centers, affected by geo-hazards.

The generation of Earthquake scenarios is also a must, in the form of spectrum compatible artificial and/or semi-artificial records representative of the seismic hazard at selected areas of critical distance. The results are provided in the form of a database with time-history records of ground acceleration, velocity and displacement for each earthquake scenario considered. Objectives consist in the following tasks:

  • Estimation of earthquake hazard based on models
  • Development of earthquake scenarios in the form of artificial ground acceleration records compatible with different earthquake hazard levels.

All the activities and the processes described above, produce huge mass of data because they are based on the probabilistic methodology (PSHA) for the calculation of the seismic hazard, as well as the deterministic methodology (DSHA) for the calculation of synthetic accelerograms from specific earthquake scenarios.  

The application of this methodologies will be tested in three case studies, located in different countries of the Mediterranean: Nafplio in Greece, Strovolos in Cyprus and Rieti in Italy.

At the end all the data will be distributed through a web open platform for access from anyone interested.

Article by: Matteo Serpetti

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A PLATFORM FOR STABLE PROJECT

A new instrument to create risk maps of Cultural Heritage at medium scale, to derive similar damage maps but before the event occurs addressing damage forecast for seismic movements impacting on the structural stability of the Cultural Heritage.

Keyword: Cultural Heritage, Historical centres, Structural stability

The STABLE (STructural stABiLity risk assEssment – H2020-MSCA-RISE-2018 – No: 823966) intention is to define a instrument that allow to host and further analyze and integrate all preprocessed data and results developed in earlier stages of the project while making use of sophisticated geospatial software and techniques. Goal is to make avalaible a set of tools to classify historical centres or block of buildings and large structures.

To achieve the goal were designed an open source software kit consisting of:

  • A desktop GIS platform
  • A dedicated database

The platform is organized to elaborate the information hold in the repository database, in specific:

  • Geological and geotechnical data
  • Seismic data
  • Deformation data

But at the same time take information from another database, called building database, a specific instrument where will be stored the building identifying with its characteristics, specially designed with the collaboration of the structural engineers, partners of the project.

All this data will be elaborate inside a GIS platform by a plugin called STABLE code, that produce structural stability model maps of the chosen case studies, based on the different level of earthquake intensity.
At the end of the activities, the final outputs of the project will be ready for the WebPortal and the final dissemination, in the form of the building Database itself.

This web portal will be created for visualization and dissemination purposes, and all primary and secondary data are intended to be included in a way that all users can easilly comprehend the intermediate processing steps.


Article by: Matteo Serpetti

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STRUCTURAL STABILITY MODELS FOR CULTURAL HERITAGE

Europe implement policies in an effort to preserve their cultural heritage, a very important part of their national history and an integral part of European tradition. A major objective of the STABLE project is to address earthquake risk maps of cultural heritage sites through the development of vulnerability assessment.

Keyword: Cultural Heritage, European project, Structural stability

In STABLE (STructural stABiLity risk assEssment – Grant Agreement No: 823966) one of the goals is to summarize the various methods used for the vulnerability assessment and conclude with the required parameters that need to be collected from each structure of the chosen case studies.

The consortium members working on the vulnerability assessment that will be performed with the implementation of a simplified method such as the macroseismic method while at the same time, for a selection of buildings, it will be performed following a more elaborate method such as the analytical, which requires the simulation of 3D models in a finite element software.

The damage potential of buildings subjected to earthquakes can be represented by a series of curves, namely the fragility curves, which provide the probability of reaching or exceeding a given damage level as a function of the intensity of the earthquake. The information coming from the fragility curves and the implementation of statistics can produce the vulnerability curves.

Exploiting the experience from recent earthquakes have provided more data that have been useful in developing models to better assess the performance of structures in order to estimate the economic losses to structures and lifelines and the social consequences such as casualties and needs for provisional accommodation.

In STABLE the case studies are analyzed with various methods (depending on the objective of the assessment but also on the availability of data and technology), investigating the vulnerability of the built environment with the hazard scenarios as the first fundamental step in the seismic risk mitigation process.

The expected risk is determined according to the following expression: Risk = Hazard × Vulnerability, where:

  • Hazard: as defined for the seismicity of the region and the accepted probability of exceedance,
  • Vulnerability: as expressed by the defined capacity of the structure as described in the following.

The estimation of damage probability will be performed by means of a simplified mechanical methodology, based on this input parameters:

  • Geometrical data (total height, number of storeys, perimeter, footprint area, average bearing wall thickness for masonry structures, Plan view at least of the ground-floor, etc)
  • Use (residential, commercial, etc.),
  • Year of construction and the relevant specification.

Article by: Matteo Serpetti

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STABLE PROJECT: LAND MOVEMENTS MONITORING METHODS, ANALYSIS AND TECHNIQUES. STATE OF ART

A project to introduce a strategy and select most efficient methods and tools for harmonization of data, criteria and indicators to be addressed for tracking of impact of environmental changes on tangible cultural heritage assets, buildings and monuments, including structural deterioration processes at a city/village scale.

Keyword: Cultural Heritage, European project, Historical Centres

 

Inside the project STABLE (co-funded by the European Commission, carried out in the context of the HORIZON 2020 program supervised by EU Authority – Grant Agreement No: 823966), the consortium members are working on the structural stability risk assessment of the cultural heritage.

In particular a part of the activities are focused on the monitoring methods and the techniques that will be used for STABLE project purposes, that is to build the deformation model and the geological, geotechnical and seismostratigraphic model of the test sites, using information coming from in-situ and satellite SAR remote sensing, optical data and geophysical methods.

The objectives are two: identify the critical areas and/or structures affected by deformation phenomena, and build the geological, geotechnical and seismostratigraphic model of the subsoil, and provide three-time histories for each seismic ambient noise measurement, representing the three components of the motion.

Until now the consortium are working on three cases study: Rieti (Italy), Nauplion (Greece) and Strovolos (Cyprus)

The Strovolos (CY) case study.

From June 2019 the Strovolos area was under study with acquisition campaigns to define the seismic ambient noise (seismostratigraphic model of the subsoil), in the perspective of providing the expected seismic shaking parameters by the subsequent local seismic response analysis, integrated all with data coming from engineering geological setting and other geological information. 

The definition of the structure and the composition of the Strovolos area, allowed to classify the case study as a non-resonant site characterized by an outcropping seismic bedrock.

Article by: Matteo Serpetti

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Stable main case study site in Greece: Historical City of Nafplion

GSH team dealt with photogrammetric image analysis of Nafplion, with the aim of estimate the geometrical characteristics of the buildings selected for assessing the structural vulnerability, according to the information shared with the NTUA group.


In the following picture the RGBNIR stereomodel from airborne acquisition at 0.20 cm

In next picture some results of 3DCity Building modeling realized using LOD2 accuracy and standard for the Building Information Modeling (BIM).

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Second STABLE Summer School Scheduled

Rethymno, Crete

Rethymno, Crete, (GR), Sept. 2020 – FORTH

The second summer school of STABLE will be held in Rethymno (Crete, GR) and will be organized by FORTH (Foundation for Research and Technology – Hellas)