1 ASSESS activities focused on a general cognitive assessment for all the schools in the region, in parallel and in support of the ordinary activities provided for by the Ordinance 3274/03 concerning the obligation to seismic verification of strategic and important buildings by the owner institutions. The development of ASSESS has followed a comprehensive, interdisciplinary, progressive, and finalized approach through an investigative methodology structured on three levels: the first one (desk approach), based on existing documents, interested all the 1,022 schools located in Friuli Venezia Giulia; the second (expeditious approach), based on field fast inspections, interested a sample, suitably selected, of a hundred buildings; the third (detail approach) was a calibration of the analysis methods developed and verification of the results obtained in the previous levels on a sample of about a dozen buildings. The ASSESS project (Analysis of the Seismic ScEnarios of the School buildings for a definition of retrofitting priorities for Seismic risk reduction) was a 3‐year project started in 2008 as an initiative of the Civil Protection of the Friuli Venezia Giulia Region (Italy) aimed at reaching a global knowledge about the seismic risk of schools in the region, so as to highlight the weaknesses and provide tools for decision support for emergency management and activation of the consequent actions for risk mitigation. ASSESS is the natural continuation of projects funded by the Friuli Venezia Giulia Region from 1976 (the year of the terrible earthquake) and developed jointly by OGS (National Institute of Oceanography and experimental Geophysics) and the universities of Udine and Trieste. The multilevel approach has proved to be very useful in detecting the cases where it was appropriate to investigate at a higher level. In practice, with this approach, the results of the evaluations obtained at Level 1 have directed the choice of the buildings suitable for the analysis at Level 2, and the evaluation of the results of Level 2 have guided the identification of the buildings suitable for the analysis at Level 3. Earthquake in Friuli 1976 REGIONAL CIVIL PROTECTION (instituted in 1986) funding data gathering L.17/76 1991‐1994 REGIONAL SEISMIC RISK MAP SEISMIC RECLASSIFICATION RISK OF RELEVANT/STRATEGIC BUILDINGS (SCHOOLS) Finalized studies 1998‐2001 2003‐2006 2008‐2011 REGIONAL SCIENTIFIC INSTITUTIONS data ASSESS project 1 2 3 integrated system GO: 134 school buildings and 15 gymnasiums Total 149 buildings PN: 208 school buildings and 18 gymnasiums Total 226 buildings TS: 122 school buildings and 1 gymnasium Total 123 buildings UD: 473 school buildings and 51 gymnasiums Total 524 buildings Total 1022 buildings UD GO PN TS 524 bldgs 149 bldgs 226 bldgs 123 bldgs SCREENING APPROACH (rapid visual screening) DESK APPROACH improvement priority survey priority improvement priority LEVEL 2 APPROACH INTERVENTION NEEDS LEVEL 3 APPROACH Bldg N. <1976 … >2003 rock hazard bldg date/retrof. BLDG FORM SCHOOL ARCHIVE 1 2 3 Livello I II III K€ PLANNING OF MITIGATION INTERVENTIONS Preliminary screening Evaluation of potential criticalities Ranking list according to objective uniform criteria Preliminary estimate of resources ASSESS Contextualised assessment Identification of intervention needs seismic verifications and targeted adjustments resources and intervention planning COMPREHENSIVE AND INTERDISCIPLINARY APPROACH SCENARIO ANALYSIS (SITE – BUILDING) MULTILEVEL ANALYSIS PROGRESSIVE APPROACH STRATEGIES 1 2 3 SCHOOL BUILDINGS PRELIMINARY CHARACTERIZATION FINALIZED APPROACH DECISION SUPPORT cognitive elements for decision support Previuos finalised studies Seismic risk Regional maps Proposal on seismic reclassification of the regional territory Analysis of the Seismic ScEnarios of the School buildings for a definition of retrofitting priorities for Seismic risk reduction
Transcript
1
ASSESS activities focused on a general cognitive assessmentfor all the schools in the region, in parallel and in support ofthe ordinary activities provided for by the Ordinance3274/03 concerning the obligation to seismic verification ofstrategic and important buildings by the owner institutions.
The development of ASSESS has followed a comprehensive,interdisciplinary, progressive, and finalized approach throughan investigative methodology structured on three levels: thefirst one (desk approach), based on existing documents,interested all the 1,022 schools located in Friuli VeneziaGiulia; the second (expeditious approach), based on field fastinspections, interested a sample, suitably selected, of ahundred buildings; the third (detail approach) was acalibration of the analysis methods developed andverification of the results obtained in the previous levels on asample of about a dozen buildings.
The ASSESS project (Analysis of the Seismic ScEnarios of theSchool buildings for a definition of retrofitting priorities forSeismic risk reduction) was a 3‐year project started in 2008as an initiative of the Civil Protection of the Friuli VeneziaGiulia Region (Italy) aimed at reaching a global knowledgeabout the seismic risk of schools in the region, so as tohighlight the weaknesses and provide tools for decisionsupport for emergency management and activation of theconsequent actions for risk mitigation.ASSESS is the natural continuation of projects funded by theFriuli Venezia Giulia Region from 1976 (the year of theterrible earthquake) and developed jointly by OGS (NationalInstitute of Oceanography and experimental Geophysics) andthe universities of Udine and Trieste.
The multilevel approach has proved to be very useful indetecting the cases where it was appropriate to investigateat a higher level. In practice, with this approach, the resultsof the evaluations obtained at Level 1 have directed thechoice of the buildings suitable for the analysis at Level 2,and the evaluation of the results of Level 2 have guided theidentification of the buildings suitable for the analysis atLevel 3.
Earthquake in Friuli 1976
REGIONAL CIVIL PROTECTION(instituted in 1986)
fundingdata gathering L.17/76
1991‐1994
REGIONAL SEISMIC RISK MAP
SEISMIC RECLASSIFICATION
RISK OF RELEVANT/STRATEGIC BUILDINGS(SCHOOLS)
Finalized studies
1998‐2001
2003‐2006
2008‐2011
REG
IONAL
SCIENTIFIC IN
STITUTIONS
data
ASSESS project
1
2
3
integrated system
GO: 134 school buildings and 15 gymnasiums Total 149 buildingsPN: 208 school buildings and 18 gymnasiums Total 226 buildingsTS: 122 school buildings and 1 gymnasium Total 123 buildingsUD: 473 school buildings and 51 gymnasiums Total 524 buildings
Total 1022 buildings
UD
GO
PN
TS524 bldgs
149 bldgs
226 bldgs
123 bldgs
SCREENING APPROACH(rapid visual screening)
DESK APPROACH
improvementpriority
surveypriority
improvementpriority
LEVEL 2APPROACH
INTERVENTIONNEEDS
LEVEL 3 APPROACH
Bldg N.
<1976…
>2003
rock hazard bldg date/retrof.
BLDGFORM
SCHOOLARCHIVE
1
2
3
LivelloIIIIIIK€
PLANNING OF MITIGATION INTERVENTIONS
Preliminary screening
Evaluation of potential criticalities
Ranking list according to objective uniform criteria
Proposal on seismic reclassification of the regional territory
Analysis of the Seismic ScEnarios of the School buildings for a definition of retrofitting priorities for Seismic risk reduction
2
In this study, the estimation of the regional seismic hazardhas played a key role. Three seismic hazard maps at differentlevels of detail have been computed: the "rock‐hazard map"refers to a rocky terrain, the "soil‐hazard map" that considersthe specific litho‐stratigraphic characteristics of the soil atthe investigated site, and the "site‐hazard map" which alsotakes into account the morphological characteristics of thesite.
The site‐hazard map pinpoints the strong spatial variability ofthe local seismic hazard and this is particularly importantwhen one has to make lists of expected damage to buildingsspread over a relatively large territory, as in the case ofschool buildings.At Level 1 (desk approach) the ground shaking is defined bythe reference peak ground acceleration (PGA) modifiedaccording to the specific soil type.For each school analyzed, a geological‐technical form wasprepared accompanied by an explanatory sheet defining thegeological, geomorphological and hydrogeologicalcharacteristics of the site.
In Level 2 ("expeditious" approach), the shaking has beencalculated by 1D modelling, calibrated on site‐specificvelocity profiles, and the vulnerability was estimated on thedesign documents of the building accompanied by visualinspections carried out by means of a method ofinvestigation specifically developed in the framework of theproject.In particular, the HVSR technique has been applied formapping the natural frequencies of the investigated sites.The HVSR technique has also allowed us to assess the effectsof geomorphology on the local seismic response and hasdriven, then, the choice between a 1D or 2D modelling.
With respect to vulnerability assessment, at Level 1 (deskapproach), reference was made to the data available in thedatabase of the characteristics of the school buildings. Anindex of potential damage for each of the 1,022 schools inthe region was estimated using to the macroseismic method(already adopted in the European project Risk‐UE). Thismethod allows us to forecast the average damage on thebasis of the level of the expected macroseismic intensity atthe site and of the building vulnerability. The so obtainedexpected damage is realistic in the case that the datacontained in the register/database correspond to the reality.This aspect must be checked, anyway, by visual inspections(at Level 2). This index should, therefore, be understood as apriority index for deeper investigations rather than as anactual indicator of the expected damage.
Potential damage index
Macroseismicintensity
Vulnerabilityof the building
MACROSEISMIC
METHOD
Input
Output
Pshake
Site‐hazard map
Soil‐hazard map
Location
Buildingfeatures
3
The structural performance is not the only indicator whenthe overall problem of seismic safety is under investigation.It is necessary, indeed, to judge all aspects that cancontribute to causing casualties or injuries.Five main bearers of potential problems have been identifiedin the ASSESS project, namely: the problems of the site, theglobal and the local structural, non‐structural deficiencies,and, finally, the functional ones.The site deficiencies refer to the fact that the place might beunsuitable because of unstable conditions (e.g., flood‐proneareas, areas with the presence of ground cavities, areascharacterized by the presence of faults, areas with potentialliquefaction, areas affected by potential landslides). Thepresence of one of these conditions implies the need toassess whether it is convenient to retrofit the building, or it ispreferable to move it to another stable location.The global and local structural characterization, focus theattention on the values of the seismic resistance of thebuilding and its parts (such as walls, roof, floors, etc.).The evaluations on the non‐structural elements (e.g.,ceilings, bookcases, fireplaces, etc.) synthesize the potentialproblems related to the presence of non‐structural elementsthat can fall or, in general, can cause damage to theoccupants.
A specific survey methodology, developed during theproject, has been used for the vulnerability assessment atLevel 2. The method, called VISUS (Visual Inspection onSeismic Unitary Scenario), is based on a quick visualinspection that allows us the identification of possibleweaknesses or critical effects in the building seismicbehaviour, both globally and locally.At the global level, the seismic performance is evaluatedusing a simplified calculation methods, calibrated on theresults obtained at Level 3 (developed by applying computercodes based on the finite element method), which, inparticular, have made it possible to calibrate the simplifiednumerical models adopted in the Level 2.In particular, the seismic performance is defined by the ratiobetween the strength capacity (calculated with simplifiedmethods developed within the project) and the referenceacceleration at the site (including possible local effects).Five classes of structural performance have been definedconsidering the design acceleration, as defined by specificregulations, using graphic symbols similar to those used todefine the energy efficiency classes.
Finally, an assessment of the evacuation system is alsoprovided, as also the possibility to leave the building quicklyis a key aspect for the assessment of seismic safety.In particular, the potential deficiencies for each investigatedaspect (site effects, global and local structural response,response of non‐structural elements, and functionalresponse) are identified and classified into 3 degrees ofseverity (absent or negligible potential damage, importantdamage, severe damage) and are represented in a graphsummary called "rose of intervention" as follows.
The summary judgment on the conditions of global seismicsafety is finally rated in terms of " safety stars." The basicconcept of the "safety stars " is the same one used in otherfields, where a judgment of quality / overall performance isrequired (e.g., the quality of the hotels, the quality of cars).After several evaluations, every single star is assigned only ifthe building meets certain requirements.
Unsuitable site (presence of heavy criticalities in the site)
Absence of criticalities in the functional parameter
Structural performance at least in the B‐class AND absence of criticalities for non‐structural parameters
Suitable site (absence of heavy criticalities in site)
Structural performance at least in the D‐class
Structural performance at least in the C‐class AND absence of heavy criticalities for all the parameters
Assignment criteriaSafety stars
SAFETY
PARAMETER
S
SITE
STRUCTURAL (global)
STRUCTURAL (local)
NON STRUCTURAL
FUNCTIONAL
Need for intervention of grade 0 (no criticalities)No action is necessary because it was not detected thepresence of problems, which could lead to importantconsequences for the people safety in the case of anearthquake.
Need for intervention of grade 1 (moderate criticalities)Need to remove / manage critical issues identified for which itis not possible to exclude the generation of difficult or riskysituations for the people safety.
Need for intervention of grade 2 (heavy criticalities)Need to remove / manage critical identified issues that, in thecase of an earthquake, can lead to severe consequences for thepeople safety.
Prof. Stefano GrimazGeneral coordinator of ASSESS project andCoordinator of University of Udine (UD, Italy) Research Unit
Dott. Dario SlejkoCoordinator of National Institute of Oceanographyand Experimental Geophysics (TS, Italy) Research Unit
Prof. Franco CucchiCoordinator of University of Trieste (TS, Italy) Research Unit
Scientific coordination of the project
ATLAS OF SCHOOL BUILDINGSPROPOSED INTERVENTIONS
TECHNICAL HANBOOKS
SCIENTIFIC HANDBOOKSfor the Friuli Venezia Giulia territory
4
The study has highlighted the importance of creating prioritylists of intervention for a better and more rational allocationof economic resources, according to criteria that take intoaccount different aspects (characteristics of the sites, thevulnerability of the structures, possible strategic role ofbuildings in terms of civil protection, etc.). Moreover, thestudy has pinpointed how the creation of priority lists basedonly on the structural vulnerability can lead to gross errorsand improper use of resources (investment for the structuralretrofitting of buildings located in potentially unstable areasunder the seismic or geological profile of the site). In thisregard it should be noted that this error can potentially becommitted even if we proceed in agreement with the moredetailed structural seismic monitoring requested by OPCM3274/03.
The methodology developed and adopted in the frameworkof the ASSESS project is a useful tool for decision support interms of civil protection, for planning seismic risk reduction,extensible, however, also to other types of strategic orimportant buildings.
The final products of the ASSESS project were: 1) a series ofguidebooks for improving knowledge of the territory of theFriuli Venezia Giulia region; 2) a series of technical guidesthat describe the complete methodology applied for theseismological, geological and structural evaluations; 3) theatlas of school buildings; and 4) a proposal plan of action.
These results, in addition of providing overall frameworks ofterritorial extension, allow us to formulate priority lists forintervention distinguished according to the different criteriaon which the interventions should be based (source offunding, area of intervention, risk level, type of intervention ,etc.) and to arrive at a rough estimate of the financialresources necessary for their implementation.
Friuli Venezia Giulia Region funding
1.500.000 € 3 years
Duration
SCHOOL ID SCHOOLTYPOLOGY
STRUCTURALPERFORMANCE
CLASS
INTERVENTIONREQUIREMENT
ROSE
ASSESSSAFETY STARS
COSTS(K€)
GO 000 XXX
GO 000 XXX
GO 000 XXX
GO 000 XXX
GO 000 XXX
Preschool
Preschool
Primary
school
Secondary
school
Secondary
school
0
Technical
verification
47÷63
1.30÷1.870
2.300÷3.150
The data collected and the results of the calculations aresummarized in forms divided into 3 main sections. The firstpresents an overview of the school with the most importantidentification data. The second section summarizes the dataon the site where the building is situated, in particular, itreports the values of seismic hazard, the geologicalinformation, any site deficiencies (if present), and theexpected site effects. The third section summarizes thestructural information (structural design, materials and theirresistance), any structural, non‐structural, and functionaldeficiencies, and suggests the appropriate countermeasures.The form reports , finally, the summary indexes: class ofperformance, intervention rose, and safety stars.
The synthetic data for the site and building characterizationare reported in lists like the one shown below, together withan indication of the range of estimated costs for theproposed interventions.
