4-LESSLOSS-Publishable Final Activity Report

8/10/2019 4-LESSLOSS-Publishable Final Activity Report

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FP6 IP Project LESSLOSSRisk Mitigation fo r Earthquakes

and Landslides

PUBLISHABLE FINAL ACTIVITYREPORT

Sept, 1st2004 Aug, 31st2007

1

Project N. GOCE-CT-2003-505448

LESSLOSS

Risk Mitigation for Earthquakes and Landslides

Integrated Project

Priori ty 1.1.6.3 Global Change and Ecosystems

LESSLOSS ANNUAL REPORT

Publishable Final Activity Report

Period covered: from September, 1st

, 2004 to August , 31st

, 2007Date of preparation: September, 2007

Start date of the Project: September, 1st

2004

Duration: 36 months

Partner Name: Gian Michele Calvi

Organisation Name: Universit degli Studi di Pavia

Revision: Final


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LESSLOSSRisk Mitigation for Earthquakes and Landslides

www.LESSLOSS.org

1. Project Execution

Earthquake and landslide risk is a public safety issue that requires appropriate mitigation measuresand means to protect citizens, property, infrastructure and the built cultural heritage. Mitigating thisrisk requires integrated and coordinated action that embraces a wide range of organisations anddisciplines. For this reason, the LESSLOSS IP has been formulated by a large number ofEuropean Centres of excellence in earthquake and geotechnical engineering integrating in thetraditional fields of engineers and earth scientists some expertise of social scientists, economists,urban planners and information technologists.

The LESSLOSS IP project has endeavoured to address both the general aims of the IntegratedProject FP6 instrument as well as the specific goals identified in the Thematic Priority 1.1.6.3(Global Change and Ecosystems), through the implementation of an ambitious but feasibletechnical research programme, which has been carried out by a consortium of prominentinstitutions (see Table 1 for the list of participants), managed in such a way so as to guarantee thatthe set objectives were met in their fullness and by means of an optimised use of availableresources. Within this framework, a number of specific technological objectives were identified andset as the prerequisites for advancement in earthquake and landslide risk mitigation:

- Development and application of improved tools for landslide monitoring- Development and application of in-situ assessment and monitoring techniques for structures- Development of innovative displacement-based earthquake-resistant design methods for

structures

- Development of innovative approaches for prediction of landslide triggering- Development of innovative probabilistic risk assessment methods of structures- Development of innovative methods for stabilisation of landslide-prone areas- Development and manufacturing of innovative anti-seismic devices- Definition of optimised structural intervention strategies for seismic vulnerability reduction- Improvement of disaster scenario prediction and loss modelling due to landslides and

earthquakes- Improvement of pre-disaster planning and mitigation policies

In order for the multi-disciplinary Science and Technological (S&T) ingredients of the project to betackled in an efficient and productive manner, it was found necessary to split the researchprogramme into three distinct areas of research; physical environment, urban areas and

infrastructures. The rationale for such subdivision is clear; each of these areas call for differentresearch expertise and approach methodologies. Then, the four main types of research activitythat are required to achieve the S&T objectives described above were identified; (i) instrumentationand monitoring, (ii) vulnerability reduction, (iii) innovative approaches for design/assessment and(iv) disaster scenarios and loss modelling.

Taking stock of the above, the S&T implementation plan can be readily obtained through themerging and cross-cutting of each of the three areas of research with the required four researchactivity types, leading to the implementation framework schematically depicted in Fig. 1, where theprojects research components are identified. The latter constitute in fact the underlying workingstructure of the LESSLOSS project.


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Participant

Role*

Participant

Number

Participant

Name

Participant

Shortname

Country

Dateenter

project

Dateexit

project

CR 47 VINCI Construction Grands Projets VCGP France Month 1 Month 36CR 48 CESI SpA CESI Italy Month 3 Month 36

*CO = Coordinator (contact Prof. Gian Michele Calvi [email protected])CR = Contractor

Research area 1Physical environment

Research area 2Urban areas

Research area 3Infrastructures

Research com ponent 1.1

Landslide monitoring and

warning system


Landslide zonation , hazard

and vulnerability

assessment


Innovative approaches for

landslide assessment

Research co mponent 1.4

Landslide disaster

scenarios predictions

and loss modelling

Research compon ent 2.4a

Earthquake disaster

scenarios predictions and

loss modelling for urban

areas .

Research compon ent 2.1

In-situ assessment, monitoring and typification

Research co mponent 2.4b

Earthquake disaster

scenarios predictions and

loss modelling for

infrastructures

Buildings Bridges, Lifelines

Research compon ent 2.2a

Development and manufacturing of energy

dissipation devices and seismic isolators

Research com ponent 2.2b

Techniques and methods for vulnerability reduction

Research co mponent 2.3a

Displacement-based design methodologies

Research co mponent 2.3b

Probabilistic risk assessment: methods and

applications

Research activity 1

Instrumentation and

monitoring .

Research activity 2

Vulnerability reduction

Research activity 3

Innovative approaches

for design/assessment

Research activity 4

Disaster scenarios

predictions and loss

modelling

.

Buildings Bridges, Underground

Buildings Bridges, Viaducts



Fig. 1. Scientific and Technological Implementation Plan

In order to meet the objectives of the project, a large variety of research activities have beencarried out by all partners involved during the three years of the project, including state-of-the-artmethodology reviews, data collection, constitutive modelling, analytical modelling, manufacture ofprototypes, laboratory testing, experimental testing, structural monitoring, software development,and methodology calibration. This has led to the production of a total of 169 deliverables during theproject, as presented in Table 2. The deliverables produced are available for download on thedissemination section of the projects web portal (www.LESSLOSS.org/main).

A major objective of the project has been to describe current best practice or usual practice in eacharea investigated. During the third year of the project, LESSLOSS produced a series of Technicalreports addressed to specific Users Communities and Stakeholders with the following titles:

LESSLOSS 2007/01: Landslides: Mapping, Monitoring, Modelling and Stabilization,LESSLOSS 2007/02: European Manual for in-situ Assessment of Important Existing

Structures

LESSLOSS 2007/03: Innovative Anti-Seismic Systems Users ManualLESSLOSS 2007/04: Guidelines for Seismic Vulnerability Reduction in the Urban

Environment


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Sub-Project 1: Landslide monitoring and warning systems

Sub-Project 1 has focused on the developmentand utilization of monitoring techniques andgeodatabases for the recognition and mitigation oflandslides. This includes: in-situ and remotemonitoring techniques (Task 1.1.1), GIS-geodatabases (Task 1.1.2); alert thresholdsthrough GIS data analysis (Task 1.1.3); anddocumentation of selected landslides (Task 1.1.4).To accomplish these objectives three mainresearch groups were engaged: University ofMilano Bicocca (UNIMIB), University ofNewcastle upon Tyne (UNEW), SwedishGeotechnical Institute (SGI-SW). Other researchgroups were involved in the collection andpreparation of datasets on landslides that havebeen used within other Sub-Projects.

Task 1.1.1: Regarding the implementation of in-situ and remote techniques for landslidemonitoring, the activity was focused on three maintopics: LIDAR for topographic mapping (Sub-task1.1.1.1), low cost GPS stations for in-situmonitoring (Sub-task 1.1.1.2), and monitoringshallow slope failures (Sub-task 1.1.1.3).

The first activity allowed to assess the potential ofLaser scanning (LIDAR) digital terrain model forlandslide hazard zonation (cfr. Deliverable 7), andfor local scale slope stability analysis (cfr.

Deliverable 6). The high resolution topographyderived by LIDAR was found to be excellent tofind old landslide scars, erosion, and otherfeatures that can be significant for landslides. Forhazard assessment, an automated algorithm havebeen implemented to process the high resolutiontopography within the Swedish landslide hazardzonation method. Tests has been performed inLilla Edet Town, situated at the banks of the Gtalv River in southwest Sweden.

The second activity allowed the development andtesting of a low cost dual frequency (L1/L2) GPS

station for in-situ monitoring (cfr. Deliverable 5). Alow cost GPS monitoring system, in comparison tocommercially available GPS systems, has theadvantage to allow an increase in the spatialdistribution of GPS stations, e.g. on a landslide,for the cost of one commercial GPS receiver.Therefore, more dense, detailed and accurateinformation on landslide movements, which is ofparamount importance, can be available forimproved modelling and monitoring. The completeGPS system was acquired for 4410.35, and iscomposed as follow: GPS receiver NovAtel OEM-G2-L1/L2W (3,435 ), GPS antenna (858.02 ),

cables (117.38 ). The receiver records both L1(1575 MHz) and L2 (1228 MHz) GPS frequencies.During the development of the station, it wasnecessary to: 1) Evaluate the GPS antenna with

benchmark testing with respect to other GPS fixedstations; 2) Improve script of GPS data recording atpredefined intervals (Refine data logging as required);Develop communication and data transfer algorithms:

scripting of automatic data transfer using GPRS;Assemble autonomous GPS monitoring system anddeploy system to a remote site in UK for furthertesting.

The third activity led to the instrumentation of a slopeparcel for in situ monitoring of hydrological processespotentially responsible for shallow landslide triggering(cfr. Deliverable 92). The field site is a 1600 m2 open-slope parcel (Montemezzo, Como lake, central ItalianAlps), 1150 m a.s.l. in elevation. The slope gradientranges from 30 to 40, and the soil cover isconstituted by 1-2 m thick glacial and slope-colluvial

debris with low to medium hydraulic conductivity (10-6m/s). The slope parcel has been instrumented with acontinuous monitoring system composed of: a raingauge, thermometers, tensiometers and equi-tensiometers (for the measurement of soil suction),FDR soil moisture measurement probes, and pressuretransducers (for the measurement of piezometriclevel). Data collection every 30 minutes allowed tobuild a significant database of rainfall events withdifferent intensity and duration. These data helped incharacterizing the dynamical behaviour of the slopesystem. The most interesting result from themonitoring activity are: 1) the high variability of the

water content vertical profile monitored with FDRsensors installed at different depths (i.e., 10, 20, 40,60, 100 cm), even within a distance of a few meters;2) the absence of a perched water table above thebedrock; 3) the relatively large amount of surfacerunoff (up to 30% of rainfall). In addition, an infiltrationtest with artificial rainfall was performed, monitoringthe hydrological response with 1 tensiometer, 2 FDRprofile probes, 6 TDR sensors (for water contentmeasurement), and cross-hole Electrical ResistivityTomography (ERT). As a result, it was possible toobserve a fast infiltration within the soil cover and asignificant infiltration within the bedrock, 1.5 m deep.

This is consistent with the observation that no perchedwater table exists above bedrock in the slope parcel.Finally, a rapid drainage of soil cover, slower for thebedrock, was also observed.

Task 1.1.2: The second task of the sub-project wasfocused on GIS-geodatabase for landslide hazardmapping. The activities of this task allowed to producea large dataset for demonstration activity in a studyarea located in the Italian Southern Alps (Val Trompiaand a sector of Val Sabbia, Lombardy, Northern Italy),510 km2 in size. For the development of the database,innovative techniques for data collection and datamanagement within ArcGis (ESRI inc.) environmenthas been applied. First, all available data have beenintegrated within a common geographic framework,


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solving problems related to heterogeneity in theformat and the scale of the original data. Then,new data on landslide have been collected with amulti-temporal aerial photo-interpretation. In all, 9different flights have been interpreted for thefollowing years: 1954, 1958, 1965, 1970, 1982,

1986, 1995, 2000, 2004. This allowed to buildtemporal inventories, where the activation of newor reactivated landslides was attributed to theperiod comprised between two successive flights.As a consequence, it was possible to investigatethe rate of recurrence of the landslides, thusallowing to estimate the temporal probability,which is of fundamental importance in hazardassessment. At the same time, a multi-temporalinventory of urban development was prepared, toestimate the variation of risk exposure andvulnerability in the last half century.Methodologically, the traditional use for

stereoscopes has been complemented with theuse of stereographic software and GPS survey.

Task 1.1.3: In order to define alert thresholdsthrough data analysis, a new approach has beendeveloped for the construction of probabilisticrainfall thresholds for shallow landslide triggering,using both a statistical (logistic regression) modeland a physically-based model. The logisticregression model was implemented using bothhourly and daily rainfall data. The spatially-distributed coupled hydrological and slope stabilitymodel (Iverson, 2000; Crosta and Frattini, 2003)was applied to the study area, using a highresolution 5x5 m Digital Elevation Model. In order

to account for the uncertainty about the modelparameters (i.e., hydraulic conductivity, hydraulicdiffusivity, soil cohesion, friction angle, soil depth) astochastic approach using Monte Carlo simulation wasused. As a result, the probabilities of failureassociated to different combinations of rainfall

intensity, rainfall duration, and potentially destabilizedarea were calculated. The thresholds derived usingthe two different approach resulted to be comparable.In addition, the stochastic physically-based modelprovided an estimation of the percentage of potentiallyunstable areas (degree of severity) that can betriggered with a certain probability of failure. Finally,the return period of rainfall responsible for landslidetriggering was studied, by using a Gumbel ScalingModel of Intensity-Duration-Frequency curves (IDF,Borga et al., 2005). In order to obtain realistic results,it was needed to account for the antecedent rainfall.For that, a simple new approach was adopted for the

correction of the return period, by filtering the rainfallmaxima with a fixed threshold of antecedent rainfall.

Task 1.1.4: Regarding the documentation of selectedlandslides, many research groups were involved. Theaim of the task was to provide all the LESSLOSSpartners with data to be used for landslide modelling.Hence, the activity of this task was mostly exploited inother sub-projects (especially Sub-Project 3 and Sub-Project 4). The list of landslides that have beenincluded in the case studies is the following (inparentheses, the partners responsible for datacollection): Nikawa landslide, Japan (NTUA); Corniglio

landslide, Italy (SGI-MI); Petacciato landslides, Italy(SGI-MI); Grand Ilet landslide, la Reunion, France(BRGM); Rudbar landslide, Iran (NGI); Las Colinaslandslide, San Salvador (UNIMIB); Bindo landslide,Italy (UNIMIB); Vajont landslide, Italy (UNIMIB).

All deliverables from this Sub-Project can bedownloaded from the LESSLOSS website:www.LESSLOSS.org.

References

Crosta, G.B., Frattini, P. (2003) Distributed modelling

of shallow landslide triggered by intense rainfall.NHESS, 3, 81-93.

Iverson, R. M. (2000), Landslide triggering by raininfiltration, Water Resour. Res., 36, 1897-1910.

Borga, M., C. Vezzani, and G. Dalla Fontana (2005),Regional Rainfall DepthDurationFrequencyEquations for an Alpine Region, Natural Hazard, 36,221235.

Figure 1.1 A landsl ide inventory: activelandslides for 1965 are drawn together with all

landslides recognized in the demonstration area.


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Sub-Project 2: Landslide zoning, hazard and vulnerability assessment

Sub-Project 2 has dealt with two main elements ofrisk analysis in landslides: i) hazard zonation, andii) vulnerability assessment. Both these topicshave gained much attention during the past fewyears due to an increase in number of disastersinitiated by landslides. Five main research groupswere engaged in Sub-Project 2: NorwegianGeotechnical Institute (NGI), VCE Holding GmbH(VCE), Swedish Geotechnical Institute (SGI-SW),University of Milano Bicocca (UNIMIB),University of Newcastle upon Tyne (UNEW). Thefollowing is a summary of activities performed inSP2 in each of the aforementioned topics:

Landslide zonation. Fairly good progress hasbeen made in the past few years in developing

methods for landslide zonation. The methods,which range from heuristic to statistical and moreadvanced probabilistic methods, are quitedifferent in details. This is due to the fact thatlandslide zonation depends on many factors, suchas scale of zonation (i.e. local and regional),method of zonation (e.g. inventory, statistical andphysically-based), type of landslide (i.e. creep,fall, slide and flow), triggering mechanism (e.g.rainfall, earthquake, human activities, etc.), andpurpose of zonation (risk assessment, land-useplanning, or stabilisation/countermeasures). Inorder to address this dynamically evolving topic,

the project partners considered the followingactivities: i) Conduct a critical review of theexisting methods of landslide hazard zonation,including the standard practice in differentcountries; ii) Based on this review, select severalmethods and apply them to different study areas -it was believed that this would reveal the positiveand negative sides (deficiencies) of thesemethods; iii) Apply different methods to the samesite - this would more specifically identify theadvantages and disadvantages of the methods;iv) Establish procedures for qualitative andquantitative assessment of the zonation methods;

and finally, v) Document the implementedlandslides zonation cases for future applicationsby other researchers.

In line with these objectives and following acomprehensive literature review, a number ofzonation methods were selected and were appliedto well-documented study areas. They include aGIS-based bi-variate statistical method usingweights-of-evidence method applied to the villageLichtenstein-Unterhausen in the Swabian Alb,Germany; landslide hazard zonation at Swedishsite by, by qualitative, and physically-based

methods which have become standardised inNorway, Sweden and Canada; physically-basedlandslide mapping at a sandy site in Sweden,different statistical (most notably the discriminant

model) and physically-based methods applied toLandslide hazard mapping at Val Trompia, Italy Val diFassa area, Eastern Alps; statistical and probabilisticmodels (such as logistic regression, frequency ratio

and first-order second-moment) for landslide hazardzonation of quick clay sites in Shien in Norway andSwedish site by. In addition, a different method,based on hydrological data of rainfall was developedfor debris flow mapping in large areas. The model wasapplied successfully to the Valsassina catchments,Southern Albs, Italy, and Ijuez catchment, centralPyrenees, Spain. Most of these methods wereimplemented in a GIS-framework which provided aflexible computational tool as well as demonstrationfeatures.

These studies have demonstrated that the methodsapplied in the present research are reliable andmature enough to be used in research and practiceand are quite effective if implemented in a GISframework. The principles and state-of the art reviewof landslide zonation are presented in Deliverable 9and the details of the applications to the study areasare given in Deliverable 94.

Vulnerability assessment. Unlike hazard zonation, theprogress towards establishing quantitative methodsfor vulnerability assessment in landslides has beenvery limited. Realising this situation, the project aimedat developing a probabilistic framework for thequantitative estimation of the vulnerability of the builtenvironment to landslides. To this end, it was noted

Figure 2.1 Example landsl ide hazard map from aLogistic Regression Model


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that there are considerable uncertainties in theparameters and models relevant in vulnerabilityassessment, and thus there was a need forquantification of uncertainty if one aims atimproving the quality of risk assessment. In thedeveloped model approach, the built environment

is subdivided into categories of elements at risk.Then Vulnerability, V, is defined in terms of boththe landslide Intensity, I, and the Susceptibility, S,of the elements at risk as V = I S. Landslideintensity is characterised by its displacement(creep type) and velocity (debris flow and rapidslides). Both the landslide intensity and theelement susceptibility have been modelled in thesecond moment sense, and First-Order Second-Moment (FOSM) approximation has been used toobtain the category vulnerability. Additionally, bothaleatory and epistemic uncertainties haveincorporated in the developed model. The aleatory

uncertainty in vulnerable elements is related to thedegree of homogeneity of category susceptibilityinside the reference area. Epistemic uncertainty isrelated to the lack of knowledge regarding suchdegree of homogeneity and in the imprecision inits estimation. Susceptibility functions have beenproposed for various elements at risk such ashouses by accounting for their type, age andmaintain ace, and for people in houses and openspaces accounting for such factors as age,gender and income. Through the formalisms ofFOSM approximations, expressions have beendeveloped for the mean and standard deviation

(or coefficient of variation) of the vulnerability.

A satisfactory application of the proposed model iscontingent on availability of susceptibility data for

the various elements at risk. So parallel with thedevelopment of the probabilistic framework, attemptshave also been made in the project to develop criteriafor susceptibility assessment. Through a large numberof calibrated numerical simulations of the response ofstructures to support motions, fragility curves have

been developed for structural damage. Similarly,fragility curves have been proposed, based onliterature data and numerical simulations, for roadsand pipelines to ground motions.

The developed model has been applied to the villageof Lichtenstein-Unterhausen in Swabian Alb(Germany) for which a landslide susceptibilityassessment was performed in the project. Thevulnerability was assessed for both structures andpeople in four distinct zones in the region. The factorsconsidered in the vulnerability assessment have beenbuildings (accounting for type and maintenance) and

people (considering, number, age and income). Theresults, which are in form of average and standarddeviation of total vulnerability for the four zones,clearly indicate the significance of accounting foruncertainty. Such results should be valuable for bothland-use planning and prioritising stabilisation andpreventive measures by decision makers.

A review of existing approaches for the estimation ofvulnerability of the built environment to landslideshave been described in Deliverable 10 and the detailsof the developed methodology as well as applicationto the study area are given in Deliverable 93 which are

both available from the LESSLOSS website:www.LESSLOSS.org.


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Sub-Project 3: Innovative approaches for landslide assessment and slope stabilit y

The work carried out in Sub-Project 3 coveredseveral different topics ranging from the study oftriggering mechanisms of landslides (rainfalls,earthquakes) to the improvement or evendevelopment of new constitutive models andpredictions of landslides displacements. One ofthe significant advances concerns the predictionof landslides displacements. Seven main researchgroups participated in Sub-Project 3:Geodynamique et Structure (GDS), AristotleUniversity of Thessaloniki (AUTH), Bureau deRecherches Geologiques et Minieres (BRGM),Institut National Polytechnique de Grenoble(INPG), National Technical University of Athens(NTUA), Stamatopoulos and Associates Co.(SAA) and University of Milano Bicocca(UNIMIB).

The models that have been tested and developedin Sub-Project 3 can be broadly classified into twocategories: those who predict permanent butlimited displacements and those required for theevaluation of long-run out slides. The formermodels are based on rather simplified constitutivemodels (equivalent linear model for instance) andare applicable to non degrading materials. Theyhave been used to highlight the importance ofspecific earthquake related features on theseismic response of slopes (topography,

directivity, flings, etc.); most often it has beenshown that previous results ignoring these effectssignificantly underestimate the induceddisplacements or ground motion amplification dueto the slope topography. The latter models havebeen the subject of new and sophisticateddevelopments; the most important requirement ofthose models is their capability of keeping track ofthe changes in geometry of the slope aslandsliding proceeds. Several models, based ondifferent constitutive assumptions, have beendeveloped or expanded for loadings related toearthquake situations. They range from an

extension of the well known Newmark rigid blockmodel to a multi-blocks model, to theimplementation of depth integrated rheologicalmodels, Bingham models, grain crushing modelsor the definition of new failure criteria (explainingthe diffuse type of failure observed in some gentleslopes). All these models were successfully usedto explain, at least qualitatively, some of theobserved slope failures either during earthquakesor following intensive rainfalls.

Using those models few additional studies werecarried out to assess the impact of a sliding soil

mass on a structure located within the slope, i.e.impacted by the moving mass, or near the crest ofthe slope. Design methods were proposed to takeinto account those effects. These methods really

improve the existing ones, mostly based on empiricalcorrelations, by relying on mechanically basedevaluations of the downstream velocity of the slidingmass. They represent a step towards more economic

design strategies: the structure can be designed toaccommodate the imposed displacements as opposedto common practice which requires stabilisation ofhuge areas of unstable slopes. In some instances ithas been possible to propose dimensionless charts forpreliminary design of piles located in the unstableslope.

Finally, new stabilising techniques for unstable slopeshave been investigated and specific numerical toolsdeveloped to ensure a rationale and efficient design.These techniques are based on the use of stiffinclusions to increase the resistance of the reinforcedsoil volume; contribution of the inclusions takes placenot only through their extensional stiffness andresistance, as in classical soil nailing, but mostlythrough their bending stiffness and resistance. Theimproved stability is checked with respect to theultimate capacity but also, more importantly, throughthe evaluation of induced displacements. This is made

possible through the development of a newelastoplastic constitutive model based on ahomogenisation technique.

All the tools have been tested, and to the extentpossible validated, by applying them to the data baseof case histories compiled by SP1. In some cases thesame slope was analysed using different models. It isinterested to note that the observed displacementpatterns can be satisfactorily predicted from differentfundamental assumptions on the constitutivebehaviour. This points out the difficulty of explainingthe observed slope failure from data based on global

observation.

All deliverables produced within this Sub-Project canbe downloaded from www.LESSLOSS.org.

Figure 3.1 Contours of plastic deformations in the caseof a one-storey building at 8m from the crest of the

slope with given load subjected to a record w ith 0.8g,when the foundation is (a) mat foundation and (b)

isolated footings.


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Sub-Project 4: Landslide disaster scenario predictions and loss modelling

Evaluation of the risk due to landslides needs agood understanding of the geological setting,material behaviour, and physical mechanisms, aswell as the use of adequate, flexiblecomputational models to make the predictions.Experience shows that getting sufficiently reliableparameters is one of the main challenges in riskanalysis. Crucial for a better comprehension andactual management of the risk is a strategycombining the definition of the predisposing andthe natural or human triggering factors, suitableconceptual models, and the identification ofrelevant physical input properties and calibrationrequirements. Being concerned with landslide riskassessment, Sub-Project 4 is closely related toSub-Projects 1, 2 and 3. Four main research

groups were involved in Sub-Project 4: Bureau deRecherches Geologiques et Minieres (BRGM),Aristotle University of Thessaloniki (AUTH),Norwegian Geotechnical Institute (NGI) andStudio Geotecnico Italiano, Milano (SGI-MI). Theachievements within the four tasks which weretackled in this Sub-Project are described below.

Task 1.4.1: Characterisation and hazardassessment of representative landslide sites:

Hazard assessment, i.e. the determination of theprobability of occurrence of unfavourable events

for a given location and time exposure, is one ofthe first steps in the landslide risk assessmentmethod. It is largely dependent on the availabilityand the quality of the (geo-referenced) geological,geo-morphological, and geotechnical data.

In this task, the data collection and analysis of theCorniglio landslide case history (mountainousApennines region of Northwestern Italy) has beenperformed. In particular, substantial data has beencollected on the landslide movements (fromDecember 1995 to March 2000) and the effectscaused to the buildings laying within the Village

area. The set of data consisted of inclinometermeasurements, building displacements (fromgeodetic surveys) and crack monitoring withinstruments placed on the damaged buildings. Inaddition, a complete census of the buildingssubjected to ground movements in the Villagearea has been conducted: for each building aphoto has been taken and the main data collected(type of structure, number of floors etc.). The datahas been collected and organised with the aim ofassessing the relationship between the absolutemovement of the ground (measured by theinclinometers), the displacement of the buildings

(identified by the geodetic survey) and thedamage occurred in terms of crack opening.Inclinometer data gaps were filled andextrapolated using the continuous displacement

recordings of nearby buildings. For a set of buildingsthe data revealed itself to be consistent and a set ofcorrelation plots has been prepared. Finally, seismicas well as non seismic 2D/3D numerical analyses

were performed for the Corniglio landslide case, usingthe provided data.

Apart from characterizing a real landslide andassessing related hazard, a bibliographical and criticalreview of the existing methods (empirical, semi-analytical, deterministic, probabilistic) was performedfor:

the estimation of permanent grounddisplacements due to ground failure(liquefaction, landslides and surface faultrupture), orientated to the seismic risk

assessment of lifelines and general lossestimation purposes;

the large scale modelling within landslidehazard assessment.

Works performed in Task 1.4.1 are detailed inDeliverables 1 (Documentation of selectedlandslides), 16 (Landslide Risk Assessment Methodsand Applications (I): Large scale models), 18 & 121(Landslide Risk Assessment Methods andApplications (III): Applications to real active landslidesites - Phases I & II), and 96A & 96B (Application ofnumerical models to case histories: Non earthquake &Earthquake cases Phase II), all of which areavailable from www.LESSLOSS.org.

Task 4.2: Loss estimation models for urban areas(mainly lives) and displacement thresholds for lifelines

In this task, a critical review of the existing methods(mostly empirical) for the estimation of the indirect economic losses of lifelines due to ground failure afterstrong earthquakes, as well as a pilot application to aurban water and gas system (Thessaloniki), were

performed to evaluate the applicability of the method.Furthermore, a classification of lifelines components(water system, gas system, waste-water system) wascombined with an attempt to concentrate theirconstruction costs, as well as a critical comparisonbetween the construction costs based on Greek andAmerican practice, accompanied with a critical reviewof the loss modelling bibliography about direct lossesof lifelines was performed. Finally, a bibliographic andcritical review of existing permanent displacementthresholds for selected lifeline elements (water,transportation) was performed.

Regarding the direct loss caused by a landslide to aset of buildings lying within the area affected by theground displacements, focus has been given on ascenario-based probabilistic estimation (First Order


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Task 4.4: Recommended practice for landsliderisk assessment

Within this task, two bibliographical and criticalreviews have been performed:

one presents the methods used inpractice to estimate building deformationsinduced by ground movements (e.g.landslides). In addition, a completeanalysis has been performed, to identifythe response parameters that govern thebehaviour of a structure subjected todifferential settlements, focusingessentially on simple reinforced concrete(RC) frame structures. Severalcharacteristics and different types ofparameters (preferably uncorrelated) ofthe structure model were examined, in

order: i) to evaluate their importance inthe structural response, ii) to provideclassification criteria and finally, iii) todefine damage limit states and to proposefragility curves useful for landslidevulnerability assessment.

the other presents the available empiricalmodels for the seismic risk analysis oflifeline elements due to ground failure and

the resulting permanent grounddisplacements caused by localized abruptrelative displacement. Also, a validation andproposal of improved vulnerability functionsfor selected lifeline elements at risk(transportation, water system) along with a

critical review of the definition of the damagestate thresholds and possible correlationbetween functional and/or economical losseswith damage states was made.

These works are part of Deliverable 93 (Vulnerabilityassessment for landslides Phase II) which can bedownloaded from the LESSLOSS website:www.LESSLOSS.org.

Apart from these works, the major research effort inthis task was to provide a synthesis of the outcomesof Sub-Projects 1 to 4 (Area 1), through Deliverable

120 (Recommended practice for landslides riskassessment), which proposes usefulrecommendations for the landslide risk assessmentpractice, thus representing an important output of theLESSLOSS project.


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Sub-Project 5: In-situ Assessment, Monitoring and Typification

Sub-Project 5 covers In-situ Assessment,Monitoring and Typification of Buildings andInfrastructure. Five research groups haveparticipated in Sub-Project 5: Arsenal GmbH(ARS), CESI Spa (CESI), Laboratorio Nacional deEngenharia Civil (LNEC), Rheinisch-WestflischeTechnische Hochschule Aachen (RWTH) andVCE Holding GmbH (VCE). This Sub-Projectfocuses on innovative methods for theassessment of the following important existingstructures:

Buildings whose integrity duringearthquakes is of vital importance for civilprotection, e.g. hospitals, fire stations,power plants, telecommunication facilities,

etc. (importance class IV according toEN1998-1:2004)

Bridges of critical importance formaintaining communications, especially in

the immediate post-earthquake period,bridges where failure is associated with alarge number of probable fatalities and majorbridges, where a design life greater than

normal is required (importance class IIIaccording to EN 1998-2:200X)

Buildings whose seismic resistance is ofimportance in view of the consequencesassociated with a collapse, e.g. schools,assembly halls, cultural institutions, etc.(importance class III according to EN1998-1:2004)

Industrial facilities, where secondary risks,e.g. the risk of release of toxic and/ orexplosive materials exist

Cultural heritage.

It is of high importance, that these structuresremain greatly undamaged and serviceable. Ifnecessary, their earthquake resistance has to beincreased based on the results of assessment.Normally a Level III assessment with a detailed

3D structural model, updated by using measureddynamic properties, has to be carried out. It is oneof the most important tasks of SP5 to integrate

experimental techniques into the assessmentprocedure.

If such investigations are carried out in the pre-earthquake phase, measures for seismic upgradingcan be undertaken in due time. In the post-earthquake

phase these investigations enable the determinationof the remaining safety and the serviceability,especially if models for the undamaged status were

Figure 5.1 Illustration of the topics involved in Sub-Project 5


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elaborated before. Hence, even the task damagedetection is important within LESSLOSS/ SP5.

Different degrees of accuracy of model updatingare necessary for the pre-earthquake assessmentand the post-earthquake assessment. In the first

case the updated modal frequencies need not befit with very high accuracy to the measuredfrequencies, since the frequency content of theinput earthquake for the earthquake analysis isknown only roughly. In most cases responsespectra from EN 1998-1 will be applied. On theother hand, when changes of modal frequenciesare used to quantify and localize earthquakedamages, the agreement between measured andcalculated frequencies should be small. Especiallyfor bridges the changes of modal frequencies dueto local damages are quite small, hence thedifferences should be maximum within 0,01 and

0,1 Hz.

Eventually, simplified vulnerability models forsome types of important structures can beelaborated from detailed case studies, which canbe also used in the context of Level I (or II)approaches. The need for such models andpossible benefits have been discussed withLESSLOSS/ SP 10 and 11 (Earthquake disasterscenarios predictions and loss modeling for urbanareas/ infrastructures) and LESSLOSS/ SP 9(Probabilistic risk assessment: methods andapplications).

The elaboration of proper Assessment Manualshas been an important task. The people to be

trained should have a fundamental education instructural dynamics and earthquake engineering(SD&EE). But the most important chapters of SD&EE,which are relevant for structural assessment, have tobe summarized in an adequate, illustrative way. Thebasis for the manuals have been the already finished

main deliverables for the first year, D19 and D20.Especially in the Application Version the procedureswill be demonstrated via case studies (e.g. chapter 3.1 Hospital Innsbruck/ Austria in D20). The examplesof investigated structures (Annex 20A) can be mainlyused for training. Also displacement based designmethodologies are important for structuralassessment. A chapter on the method and anexample of application have been elaborated incooperation with LESSLOSS/ SP8. Further, at leastreferences on methods for the reduction ofvulnerability, on energy dissipation devices andseismic isolators have been given especially in the

application version of the Assessment Manual. Thereferences and even some summaries have beenelaborated in cooperation with LESSLOSS/ SP6 andSP7.

The most innovative task of LESSLOSS/ SP5 is theUpdate of vulnerability estimates via monitoring.Twomain deliverables D19 and D20 and two smallerdeliverables were elaborated. D19 and D20 mean thebackground documentation for the European Manualfor in-situ Assessment of the Earthquake Resistanceof Important Existing Structures. Further, the layout fora European Assessment Code was elaborated.

.


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Sub-Project 6: Development and manufacturing of energy dissipation devices and seismicisolators

The aim of Sub-Project 6 (Development andmanufacturing of energy dissipation devices andseismic isolators) is the development andvalidation of two innovative antiseismic devices (alow stiffness isolator and an electroinductivedamper), the improvement of the performances ofa sliding isolator with curved surface and theevaluation of benefits and limits of isolationsystems based on steel hysteretic dissipaterscoupled with flat sliders. Five main researchgroups have participated in Sub-Project 6:EnteNuove Tecnologie, lEnergia e lAmbiente (ENEA),Applicazione Lavorazione Giunti Appoggi SpA(ALGA), Maurer Soehne GmbH & Co. KG(MAURER), STAP SA (STAP) and Vinci

Construction Grands Projets (VCGP).The Low Stiffness Isolator (LSI) was developed byALGA and is particularly addressed to lightstructures like family houses. The electroinductivedamper (DECS), developed by ALGA, is anenergy dissipater based on the interaction of adiamagnetic material, like aluminium, with anelectric field generated by permanent magnets.The Sliding Isolation Pendulum (SIP) developedby MAURER is an improved curved surface slider,capable of withstanding high weights for longperiods without creep effects and high velocity

deformations without damages due to friction.Finally, several types of Steel Hysteretic Elements(SHE) of different geometries and materials, havebeen analysed and tested in order of evaluatingthe benefit and the limits of such devices, withparticular regards to the re-centring capabilities.All the abovementioned devices have beennumerically modelled by ENEA and tested on theENEA shaking table, using a suitable mock-up(300 kN weight) capable of providing significantforces on the devices in the acceleration andfrequency ranges of interest, using several naturaland artificial acceleration time histories purposely

developed. Applications to real structures likefamily houses, civil buildings and bridges havebeen analysed in cooperation with ENEA, STAPand VCGP.

Low Stiffness Isolators have been developed byALGA with the aim of applying the base isolationtechnique also to light structures such as two-three storeys family houses. As a matter of fact,with the standard isolators, the horizontalstiffness is normally too high to reach the optimalisolation period (2 s) for light structures. Lowstiffness isolators are made, like traditional ones,

of rubber layers and steel plates, but with a largeinternal hole filled with a suitable material withsmall horizontal stiffness, capable of dissipatingenergy. The isolator stiffness, in fact, increases

with the rubber shear modulus (G) and the isolatorcross section, while decreases with the total rubberheight. It is worth noting that the minimum G modulus

for dissipating rubber compounds is about 0.4 MPa;moreover, the cross section can not be reduced toomuch, since the isolator has to carry the vertical load;finally, the total rubber height can not increased toomuch to avoid instability. Thus, due to theabovementioned reasons, it can be quite difficultisolate light structures. The innovative idea developedin LESSLOSS is to use the minimum reinforcedrubber cross section to carry the vertical load withadequate rotational inertia and to fill the internal holewith a different material to minimize the horizontalstiffness. The rubber compound used for the LSI isvery soft, having a G modulus of about 0.4 MPa and a

damping coefficient of 10%; the internal core ismade of polinorbornene. Two sets of isolators havebeen manufactured and tested: the first is circular andthe second is square; they have an internal cylindricalhole filled with soft material. Prototypes isolators havebeen tested at the ALGA laboratory on a dynamic testmachine to evaluate their properties in term of verticaland horizontal stiffness and damping. Then, thesquare isolators have been used at ENEA Casaccialabs, in Rome, for a shake table campaign on a baseisolated frame subjected to many earthquakes. Testsprovided very good results.

The DECS operative principle is based on thegeneration of electrical power from mechanical(vibrational) power, using the device deformationscaused by the earthquake; the aim is that to limit anddamp the displacements of the protected structure.The generated electric energy is then dissipated intoheat. DECS can be passive or semi-active. In passivedevices the energy conversion is uncontrolled; insemi-active devices the energy dissipation is

modulated, usually by employing low power levelcontrolling auxiliary devices. In the framework of theLESSLOSS project ALGA designed and manufacturedtwo devices with maximum reaction force 40 kN and

Figure 6.1 Finite element model of a Low StiffnessIsolator


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1000 kN, respectively. The first one was a scaledmodel particularly addressed to the shaking tabletests, which are aimed at simulating the responseof an isolated mass (representing for example adeck) supported by low stiffness rubber isolators.The aim of these tests was to experimentally

verify the benefit, in terms of structural responsereduction, which is obtained by adding an energydissipater to a seismically isolated structure. Thefull scale DECS has been designed with amaximum capacity of 1000 kN to verify thefeasibility of a damper to be installed on a realstructure such as a bridge deck and to comparethe response, the dimensions, the initial andmaintenance costs, with respect to other dampers(such as hydraulic devices) already available onthe market. The full scale DECS was tested in theALGA laboratory on the dynamic test machine. Inboth the experimental campaigns, DECS showed

a very good capacity of dissipating energy withvery stable hysteresis loops.

MAURER designed and manufactured lots ofdifferent SHE, which have been tested on theENEA shaking table, coupled with flat sliders. Thespecific objective of this activity was that ofevaluating the benefits and limits of such devices,and in particular, assessing and validating therecently proposed criterion for evaluating the re-centring capability of the isolation systems. Itshould be noted that this study represents animportant novelty, because, at present, the re-

centring matter is dealt within the: AASHTO:Guide specifications for seismic isolation design;Eurocode 8: EN 1998-2: Design of structuresfor earthquake resistance - Part 2: Bridges; EuroNorm: prEN 15129: Anti-seismic Devices.However, the above standards adopt completelydissimilar evaluation approaches and the severityof the requirements specified differs by one orderof magnitude. To conduct the studies within theframework of LESSLOSS, several steel hystereticelements were designed, manufactured andsubjected to characterization tests at the MunichBundeswehr University. The steel hysteretic

element is the Triangular Plate Damper type,which was selected for its ease in bothdimensioning and construction but especially sobecause it has not been subject to any limitationspatent-wise. Just four types of elements wereretained for the two exacting testing campaigns,which were distinguished by the following valuesof (post-elastic)/(elastic) stiffness ratio =0,022 =0,031 =0,034 and =0,071 respectively. Themock up was a SDOF isolation system comprisingfour PTFE sliding spherical bearings, one to threesteel hysteretic element(s) and a rigid reactionmass equal to 12,2 and 16,4 t. The seismic inputs

were a synthetic time history specifically preparedby ENEA, as well as various natural records, such

as the Alkion, Bolu Mountain, Colfiorito, to name afew. Several devices of each one type of elementwere used during the tests. Each device wassubjected to a progressively increasing seismic input,so as to obtain displacement time-histories withdifferent values of ductility ratio m (from 1 to 11). It is

worth mentioning that, among other achievements,this testing campaign has allowed the verification ofthe restoring capability evaluation according to thethree above mentioned standards. In conclusion, theexperience gained with the flat surface sliders coupledwith hysteretic elements proves that these systemsare easy to design and manufacture, user-friendly,reliable and repeatable. Nonetheless, their restoringcapability needs to be verified on a case-by-casebasis.

SIPs have been designed and manufactured byMAURER with the specific objective of experimentally

substantiating/disproving the characteristics andadvantages claimed by curved surface sliders (frictionpendulum systems). To wit, the testing campaign hasinvestigated the effects of substantial changes in thesupported mass and its claimed capacity to minimizethe adverse torsional motions that could take place innon-symmetrical structures. The mock-up used to thispurpose was essentially the same used for the testwith SHE, with the following important alterations, towit:: a) the Nr. 4 PTFE sliding spherical bearings werereplaced with as many Sliding Isolation Pendula (SIP)manufactured by Maurer, where the special slidingmaterial MSM is used, which is suitable for high-

speed movements; b) the unidirectional guides wereremoved from the rig, thus turning the SDOF systeminto a three-degree of freedom system (translationsalong x and y axes, rotation about z axis); c) thereaction mass was increased to 29,1 t. Twenty testswere conducted with the symmetric massconfiguration. The results were in perfect accordancewith the mathematical modeling estimate. Then fourconcrete blocks (4x1,15 t = 4,6 t) were removed fromone side of the isolated frame and the same seismicinput were applied. No appreciable torsional effectswere observed, thus the theoretical prediction wasconfirmed. Finally, another important objective is that

of investigating the effects of creep induceddeformation on the break-away force of curvedsurface sliders. This experimental test, whichrepresents an absolutely innovative approach, is stillin progress.

In conclusion, all the initially planned goals have beenreached in Sub-Project 6. Innovative antiseismicdevices like Low Stiffness Isolators andElectroinductive Dampers have been developed andsuccessfully qualified. These devices are ready for thefirst applications. In addition, more traditional deviceslike sliders (with flat or curved surfaces) have been

deeply studied and tested and their behaviour hasbeen improved.


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Sub-Project 7: Techniques and methods for vulnerability reduction

The aim of Sub-Project 7 of the LESSLOSSProject is the reduction of the seismic vulnerabilityof buildings and infrastructures. This cancorrespond to very different interventions, as thereare many types of structures, many materials andmany ways to reduce vulnerability. This explainsthat a variety of topics is treated. Six researchgroups have participated in Sub-Project 7:Universite de Liege (ULIEGE), CentreInternacional de Mtodes Numrics en Enginyeria(CIMNE), Istanbul Technical University (ITU),Istituto Superior Tcnico (IST), Middle EastTechnical University (METU), AccionaInfraestructuras (ACCIONA) and the University ofBristol (UBRIS).

A synthesis of the work performed during threeyears by seven Institutions has been published inthe form of a book in which the reader can havean overview of the output of research. Theoverview is already wide, since the book has over300 pages. Its reference is: Guidelines forSeismic Vulnerability Reduction in the UrbanEnvironment, IUSS Press, 2007, A.PlumierEditor, ISBN 978-88-6198-008-2.

The first chapter deals with the screening ofbuildings on an urban scale to identify which needretrofitting. In the second chapter, conventional

methods for retrofitting are described. In all thefollowing chapters, new techniques for retrofittingare presented.

The application of Fibre Reinforced Polymers(FRP) on existing structures is a technique whichhas developed a lot recently. The content ofChapter three is related to the design of FRPsolutions: a user friendly design tool, experimental

data on durability and fatigue and a design methodconsidering the contribution of steel rebars and FRPto resistance. An effective numerical model forcomposite is presented. Chapter three also describes

experimental studies on masonry infill which FRP caneffectively reinforce against transverse motion and fortheir in-plane strength. Rehabilitation using thattechnique can be applied at an urban scale.

The use of dissipative devices to reduce thevulnerability of structures is the subject of Chapterfour. The technique is applied to precast concreteportal frames and to steel frames with concentricbracings.

The use of base isolation for seismic upgrading ofhistorical buildings is developed in Chapter five, in

which a displacement - based method is applied to alight house.

The mitigation of hammering between buildings, with amethodology to face various situations, is the subjectof Chapter six. A displacement based methodology ofanalysis for underground structures in soft soils ispresented at Chapter seven.

The Report : Guidelines for Seismic VulnerabilityReduction in the Urban Environment, focuses onpractical applications rather than on theory, but it canserve as an orientation to more detailed explanations

about the research work of the different Institutionsand the results obtained, as those information can befound in the specific deliverables of the LESSLOSSproject, available on the LESSLOSS website(www.LESSLOSS.org).

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Figure 7.1 A reinforced concrete infilled frame strengthed with FRP and model with infill struts and FRP ties


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Sub-Project 8: Displacement based design methodologies

Sub-Project 8 deals with the displacement-baseddesign of buildings, bridges and equipment inindustrial facilities, Seven research groups haveparticipated in this Sub-Project: University ofPatras (UPAT), Commissariat lEnergieAtomique (CEA), DENCO Development andEngineering Consultants Ltd. (DENCO), InstitutNational Polytechnique de Grenoble (INPG),INSA-LYON (INSAL), Joint Research Centre(JRC) and the University of Pavia (UPAV).

Structural displacements and memberdeformations do not enjoy a primary role incurrent force-based seismic design. Theirabsolute magnitude is of interest only for aspectsconsidered of secondary importance for seismic

performance and safety: for the calculation of P-

effects, the limitation of non-structural damage inbuildings by controlling interstorey drifts, thecontrol of pounding between adjacent structures,the design of bearings and moveable connectionsin bridges, providing clearances and overlaplengths to avoid unseating, etc. In the mainphases of current force-based design, namely thatof member dimensioning for given strengthdemands and of member detailing, structuraldisplacements and member deformations enter inan average sense and indirectly, through theirratio to the corresponding value at yield: through

the displacement ductility ratios, global and local,which determine the global behaviour factor andthe member detailing requirements, respectively.Recent years have seen an increased interest inthe absolute magnitude of displacements anddeformations as the basis of seismic design. Themain reason for this is the recent recognition thatdisplacement- and deformation-, rather thanstrength-, demands and capacities, are whatdetermine seismic performance and safety. Theearthquake is a dynamic action, representing for astructure a demand to withstand certaindisplacements and deformations, but not specific

forces. Ductility factors, although convenient forthe determination of strength demands, are poordescriptors of deformation capacity, as theintroduction of another, sometimes ill-definedvariable, i.e. the yield displacement ordeformation, often increases, rather than reduces,uncertainty.

In displacement based design seismicdisplacements are the primary response variablesfor the design: design or acceptance criteria andcapacity-demand comparisons are expressed interms of displacements rather than forces. Since

their introduction in the early 1990s,displacement-based concepts have found theirway more into seismic evaluation or assessmentof existing structures, than in the design of new

ones. For existing structures the application ofdisplacement-based concepts is ratherstraightforward: members sizes and reinforcement areknown and simple or advanced analysis procedures

can be employed for the estimation of inelasticdisplacement and deformation demands throughoutthe structure, to be compared with memberdeformation capacities. Full application ofdisplacement-based design to new structures is stillfacing difficulties. For example if the reinforcement ofconcrete members has not been determined yet, thedistribution of a given global displacement demand toindividual members is difficult. Moreover, directprocedures for reinforcement dimensioning on thebasis of given deformation demands have not beendeveloped yet, to replace time-proven strength-basedprocedures for member dimensioning. Recourse to

iterations between member design and nonlinearanalysis is often necessary to overcome the firstdifficulty. To bypass the second one, practically allDBD procedures proposed so far translate globaldisplacement demands into a global strength demand,expressed in terms of a design base shear.

Nonlinear static (pushover) procedures of analysis gohand-in-hand with displacement-based seismicdesign, as they are normally employed for theevaluation of a design produced by DBD. They alsoshare with DBD common acceptance and evaluationcriteria, namely the magnitude of inelastic member

deformations. Nonlinear analysis, static (Pushover) ordynamic, is also accepted by Eurocode 8 for thedesign of new buildings without recourse to a globalbehaviour factor. In such an approach members aredimensioned/checked on the basis of acceptancecriteria in terms of deformations, instead of forces.Nonetheless, the elaboration of such criteria is left forthe National Annexes of Eurocode 8. A similar gapexists in Eurocode 8 regarding member nonlinearmodels to be used within the framework of nonlinearanalysis, static or dynamic. An additional difficultycomes from the fact that common nonlinear membermodels require the geometry and the reinforcement of

members to be known in detail a-priori, while suchinformation is not available unless the structure hasbeen fully designed. So, although Eurocode 8 hasopened the door for the use of nonlinear analysis fordirect seismic design, it has failed so far to provide thetools needed to use this option. This is simply due tolack of widely accepted member acceptance criteria interms of deformations, simple and validated nonlinearmember models, etc.

Displacement-based seismic design has now come ofage, especially for buildings. The work in Sub-Project8 (Displacement based design methodologies) ofLESSLOSS contributed to further advancement ofDBD, both for buildings and for bridges, by focusingon special crucial subjects and unresolved questions.


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The work has been divided in two distinct butclosely knit parts: one for buildings and anotherfor bridges. Both for buildings and for bridges, thework has covered both the estimation ofdisplacement and deformation demands and thatof component force and deformation capacities.

For buildings, the work on analysis for estimationof displacement and deformation demandsevaluated nonlinear analysis methods and thecorresponding modelling at various degrees ofsophistication, on the basis of experimentalresults (including identification of modelparameters affecting reliability of deformationpredictions) and compared nonlinear dynamic to

linear analyses (static or modal) for irregular in planbuildings. It covered also soil-structure interaction in3D, including uplift and the effect of base isolation. Itconcluded with a description of the latest advances inadaptive pushover analysis for irregular buildings.Tools for the estimation of displacement and

deformation demands in buildings were developed, inthe form of effective elastic stiffness of concretemembers for use in linear analyses emulatingnonlinear ones and of ductility-dependent equivalentdamping. Regarding component force anddeformation capacities, acceptance and design criteriain terms of deformations at various performance levelswere developed and proposed, for concrete membersunder uni- or bi-directional cyclic loading.

The work on bridges included an overview ofdisplacement-based design methodologies forbridges without seismic isolation (i.e., with integraldeck and piers), including an evaluation ofiterative procedures. A new approach for the cost-effective and rational design of the piers and thedeck directly on the basis of displacement and

deformation demands without analysis iterations,was proposed and evaluated through applicationto real bridges and comparison of cost-effectiveness and performance with those of theirforce-based design counterparts. The aspect ofestimation of displacement and deformationdemands was catered for via comparisons ofnonlinear static analysis with dynamic and withlinear analysis. Moreover, a method for adaptivepushover analysis for bridges was proposed andimplemented and its advantages overconventional pushover analysis weredemonstrated. Tools for the analysis and for DBD

were developed on the basis of test results andnumerical approaches. These tools included thesecant-to-yield stiffness and the equivalentdamping of concrete piers. Regarding the

component force and deformation capacities, the workfocused on concrete piers, developing simple rules forthe estimation of their flexure- or shear-controlledcyclic ultimate deformation, on the basis of test resultsand numerical analyses. A distinct part has beendevoted to seismic isolators, dealing with theevaluation of their displacement and re-centringcapacity and the effect of exceedance of isolatordisplacement capacity on the bridge seismicresponse. This latter work produced a proposal forimmediate implementation into an amendment of there-centring requirements in EN 1998-2:2005 forseismic isolators. The effect of the variation of theaxial force of friction pendulum isolators on theresponse of the isolated bridge has also been studiedand was found, in most cases, to be minor.

On a side development referring to building-likeindustrial infrastructures, procedures were proposedfor the construction of acceleration and displacementfloor spectra for the seismic design of equipment(piping, tanks, pumps, storage racks, etc.). This fills agap in seismic design codes, that currently haveempirical rules for this purpose.

Figure 8.1 (a) North West view of a ful l scale test building , (b) Finite element mesh and

concentrated masses and (c) fibres in a given section.


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Sub-Project 9: Probabilistic risk assessment: methods and applications

Probabilistic thinking is connatural to earthquakeengineering and pervades every aspect of thisdiscipline, from the definition of the hazard to theassessment of structural response, with theassociated consequences of damages, threat tolife, direct and indirect monetary losses.

Probabilistic thinking has actually been at the rootof the development of modern earthquakeengineering in the second half of the last century,and reflections of this thinking permeate more orless visibly the present day seismic designregulations.

Recent disastrous earthquakes occurred in highlydeveloped and/or populated areas have brought

about the need for an expanded and explicitrecourse to probabilistic approaches for two mainpurposes: better control of the expectedperformances of new construction, assessment ofthe expected losses with accompanyingdevelopment of mitigation measures, for the builtenvironment.

Major research programs have been launched tocope with the above issues, the larger and moresystematic ones being currently underway in theUS. LESSLOSS is the first European projectwhich includes two sub-projects: SP9 and SP10,

dealing with probabilistic risk analysis, ofindividual structures and infrastructures, and ofurban areas, respectively. Seven research groupswere involved in Sub-Project 9: Universit diRoma La Sapienza (UROMA), Faculdade deEngenharia da Universidade do Porto (FEUP),University of Bristol (UBRIS), University ofLjubljana (ULJ),. Univeristy of Naples Federico II(UNAP), Universidad Politcnica de Madrid (UPM)and the University of Surrey (USUR).

The objective of SP9 has consisted in examiningthe more valid existing procedures, to

advance/modify them as deemed appropriate, topropose one or more of these as suitable forgeneral use in practice, to validate and exemplifythem through a number of applications, toconsolidate the proposal in a final documentcontaining, in addition to a detailed description ofthe selected methods all the informationnecessary to carry out the analysis.

The stated objectives have been achievedthrough a number of intermediate stages, the endof which being marked by the emission of one ormore documents.

Stage 1 consisted essentially of a critical review ofavailable engineering approaches, condensedinto a comprehensive documents of about 120

pages, plus one original document providing aprobabilistic extension of a well-known nonlinear staticmethod of assessment.

Stage 2 followed in logical sequence, with theproduction of a voluminous document of more than200 pages containing a number of applications tosuch structures as 2D and 3D RC frames, acontinuous multi-span bridge, a steel momentresisting frame and an oil-storage tank. At the sametime, during Stage 2, a critical review of probabilisticassessment methods for key infrastructural systemswas undertaken, with focus on road networks,industrial plants and water-supply systems, resultingin three corresponding state-of-the-art reports.

Finally, in Stage 3 the maturity acquired through theprevious stages of work has allowed the production ofa manual presenting in a self-contained manner thefinal selection of methods for structure-specificassessment, accompanied by worked-out examples ofapplication. Additionally, the parallel activity on

selected infrastructures has progressed with theproduction of three follow-up research documents,each dealing with a specific aspect identified duringthe review phase (Stage 2) as in need of furtherinvestigation.

Based on the results of SP9, it can be stated that, asfar as the (relatively) simpler task of probabilisticseismic risk assessment for individual structures, suchas buildings and bridges, is concerned, the (too) fewEuropean research groups active in the field can beconsidered at a stage of maturity comparable to thatof the leading institutions worldwide (see the

LESSLOSS Report number 6). It is then stronglyrecommended to improve on quantity, rather thanquality. As far as infrastructures (transportation,water-supply, gas and electricity networks and

Figure 9.1 Identification of failure modes for a planeframe


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industrial plants) are concerned, a considerablymore data intensive and complex problem due tothe many multi-level interactions betweencomponents, the situation is less advanced, andfar greater resources are needed.

With the long-term goal of being able to quantifythe actual total societal cost of our builtenvironment in mind, consisting of initialconstruction cost but also of the direct and indirectloss incurred in catastrophic events such asearthquakes, probabilistic methods do appear toprovide the most rational answer. Much researcheffort is to be devoted towards the achievement ofthe mentioned goal, the results of which need tobe spread broadly within the scientific andprofessional communities. A major and decisivestep awaiting solution from future research is thatof transforming existing assessment methods into

tools for direct design.

References

Sub-Project 9 [2007] Probabilistic Methods forSeismic Assessment of Existing Structures,LESSLOSS Report No. LESSLOSS-2007/06, 163pages.

Jalayer, F., Franchin, P., Pinto P.E. [2007] Ascalar damage measure for seismic reliabilityanalysis of RC frames, Earthquake Engineering& Structural Dynamics, Wiley, Special Issue on

Seismic reliability Analysis of Structures CornellC.A. (Editor), in press.

Franchin, P., Pinto, P.E. [2007] Transitability ofmainshock-damaged bridges, Proc. 1st Joint US-Italy Workshop on Seismic Design and

Assessment of Bridges, Pavia, Italy, April 19th 20th.

Dolek, M., Fajfar, P. [2007] Simplified probabilisticseismic performance assessment of plan-asymmetricbuildings, Earthquake Eng. Struct. Dyn., Vol. 36, inpress, DOI:10.1002/eqe

Peru, I., Fajfar, P. [2007] Prediction of the force -drift envelope for RC columns in flexure by the CAEmethod, Earthquake Eng. Struct. Dyn., Vol. 36,accepted for publication

Vega, J., Gaspar, J.M, Benito, B., Pastor, J.A.,Alarcon, E. [2007]: Bridge Response Under SeismicAction (in Spanish), Proc. 3rd Spanish Congress onSeismic Engineering.

Romo, X., Guedes J., Costa A., Delgado R. [2006]Seismic Risk Assessment of Reinforced Concrete

Structures, Proceedings of the 1st European Conf. onEarthquake Engineering and Seismology. Geneva,Switzerland.

Delgado, P., Monteiro, R., Marques, M., Costa, A.,Delgado R. [2006] Probabilistic seismic safetyassessment of bridges application to a real case,"Proceedings of the 1st European Conf. on EarthquakeEngineering and Seismology. Geneva, Switzerland.

Kazantzi, A.K., Righiniotis, T.D., Chryssanthopoulos,M. [2007] Fragility and hazard analysis of a weldedsteel moment resisting frame, Jnl Earthquake

Engineering, to appear.

Di Carluccio, A., Manfredi, G., Iervolino, I.,Fabbrocino, G. [2007] Fragility analysis of liquidstorage steel tanks in seismic areas Proc. of ISEC-44th Structural Engineering and ConstructionInternational Conference, Melbourne, Australia.


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Sub-Project 10: Earthquake disaster scenario predictions and loss modelling for urbanareas

The overall aim of Sub-Project 10 has been tocreate a tool, based on state-of-the-art loss

modelling software, to provide strong, quantifiedstatements about the benefits of a range ofpossible mitigation actions, in order to supportdecision-making by urban authorities for seismicrisk mitigation strategies. A further larger aim hasbeen to contribute to a seismic risk mitigationpolicy for future implementation at European level.

Among the European cities for which lossestimation studies have been carried out areIstanbul, Lisbon and Thessaloniki, and tools,using GIS mapping, have been developed byresearch teams in each of these cities; these were

made available for further development toexamine mitigation strategies within SP10.Related research studies on ground motionestimation, on the assessment of humancasualties, and on the evaluation of uncertaintyhave been carried out by other research teamsacross Europe which includes INGV, UCAM andUSUR, respectively.

The idea of SP10 was to draw this expertisetogether to improve the loss-modelling toolsavailable, to apply them to evaluate some of thepossible routes towards earthquake risk mitigation

listed above, in collaboration with the cityauthorities, and to present the results to the cityauthorities.

Methods

The partners in the SP10 project and theirparticular role in the SP10 project are shown inFigure 10.1 below with the overall structure of theSub-Project as set out in the accompanyingfigure.

In all three of the cities, a common general

approach to loss modelling has been adoptedwhich includes representing the earthquakehazard as a set of alternative ground motionscenarios (typically those with an expected returnperiods of 50 and 500 years), and applying theground motion over a target area of knownpopulation and building stock. Losses have thenbeen estimated for this target area in terms oflevels of building damage and human casualtiesexpected both in the existing state of the targetarea, and after certain selected potentialmitigation actions have been carried out. This hasbeen done in each case using building stockclassifications and vulnerability data specific to theparticular city concerned. In each case the scopeof the proposed mitigation action has been

described, and its expected benefit in terms ofreduced losses and human casualties has beendetermined. For each city GIS maps of the ground

motion scenarios and the expected losses both beforeand after mitigation have been presented. And also, ineach case some preliminary assessment ofuncertainty has been made.

Findings

1. For Istanbul, the proposed mitigation action wouldbe to upgrade all those structures which have thehighest propensity to collapse in the event of the500-year scenario earthquake (4.1% of all thereinforced concrete frame buildings in the city).Having carried out this mitigation programme, in

the event of the 475-year earthquake, there wouldbe a reduction of 94% in the number of collapsedbuildings, and of 92% in the number of deaths,saving 29,000 lives.

2. For Thessaloniki, several possible mitigationactions were considered. One proposed mitigationaction would be to upgrade the worst 5% of thereinforced concrete building stock, the framebuildings built before 1983 up to currentstandards. Having carried out this mitigationprogramme, in the event of the 500-yearearthquake scenario, there will be a reduction ofabout 40% in the number of buildings destroyed,and people killed.

3. For Lisbon the proposed mitigation action isstrengthening of all masonry buildings built before1985 on hard and intermediate soils, masonrybuildings built between 1985 and 2001 located onintermediate soils and RC buildings built between1961 and 2001 located on intermediate soils(numbering 371,888 buildings in all, 78% of thetotal). Having carried out this mitigationprogramme, in the event of the 500-yearearthquake scenario, there will be an expectedreduction of between 28% and 65% in severelydamaged buildings, 38% to 78% in destroyedbuildings, and between 38% to 71% in numbers ofdeaths.

SP10 loss modelling has produced results which areindicative of the possible reduction in losses whichcould be achieved by building retrofit programmes.Uncertainty in ground motion and damage is high, butthe benefit in terms of proportional reduction in lossesmay not be much affected by uncertainties in absolutevalues. Further work should involve systematic

building-by-building assessments of the high-riskclasses, involving action by urban authorities. Inaddition, SP10 has generated the development of anew approach to casualty modelling and application to


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European conditions and a proposal for aprobabilistic loss estimation framework and

assessment of uncertainties in modellingmethodologies.

Partner Roles

University ofCambridge,Department ofArchitecture(UCAM)

Coordinator,vulnerability,casualties

BogaziciUniversity,EarthquakeResearch Institute(KOERI)

Lossestimation,Istanbul

LaboratrioNacional deEngenharia Civil

(LNEC)

Lossestimation,Lisbon

AristotleUniversity ofThessaloniki(AUTh)

Lossestimation,Thessaloniki

Istituto Nazionaledi Geofisica eVulcanologia(INGV)

Groundmotionscenarios

University ofSurrey (USUR)

Uncertaintyandprobabilisticmethods

MunichRe Overview,economicimpacts

Figure 10.1 Partners in the SP10 project, their particular role and the overall structure of the Sub-Project.


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Sub-Project 11: Earthquake disaster scenario predictions and loss modelling forinfrastructures

The European experience and research onseismic vulnerability and damage scenarios ofInfrastructural Systems (IS) are at a less

developed stage than in the case of buildingdamage analyses and scenarios. This explainswhy the emphasis of Sub-Project 11 has beenplaced more on the tools for achieving thedifferent steps of a scenario and on theirapplication, rather than on the (economic) lossevaluation, and on the impact of the loss offunction of neuralgic IS on economic and socialactivities in the immediate post-disasteremergency. Destructive earthquakes of recentdecades in Europe did not cause large scaledamage to IS, most likely because the magnitudeof such events has rarely exceeded 7.0, and IS

damage is strongly driven by localised permanentground deformations (e.g. caused by soilliquefaction, land sliding, surface faulting) which inturn depend on the source energy and theshaking duration.

The main verification of the IS seismicperformance should address the DamageLimitation State, in conformity with Eurocode 8Part 4; hence, the severity of the applicableseismic action should preferably be compatiblewith the appropriate return period (order of 100years), although it should be limited to that.

Since the advanced probabilistic approaches toseismic damage assessment of infrastructural

systems IS (as used e.g. in USA) may at the presentbe oversized for Europe, the objectives of LESSLOSSSP11 were:

Select and apply tools for generating urban-scale scenarios of earthquake shakingparameters, including transient ground strain,but also of permanent (tectonic) grounddeformations (Task 2.4b.1);

select/define vulnerability functions for IScomponents (Task 2.4b.2);

identify requirements for inventories of urban ISsystems;

develop tools for constructing IS damagescenarios (Task 2.4b.3);

demonstrate their performance throughapplication to selected cases (Task 2.4b.4).

In Figure 11.1, the flow chart of SP11 is depicted, fromthe definition of the earthquake shaking scenariotoward the creation of damage and loss scenarios.

The partners participating in SP11, together with theirinvolvement in each of the Sub-Tasks are listed inTable 11.1. Most of the partners have been involved inthe whole SP, with the only exception of INGV whichfocussed its activity on the preparation of theearthquake shaking scenarios, constituting the base of

the analysis carried out by the other partners. Theformer participant MUNICH-RE resigned from theSP11 team at the end of the first year of the project.

Table 11.1 involvement of the partners for each of the tasks of SP11.

Partner

Task 2.4b.1Earthquake

shakingscenarios

Task 2.4b.2Improved

vulnerabilityfunctions

Task 2.4b.3Damage

estimationmodels

Task 2.4b.4Creation of

damagescenarios forselected cities

COORDINATOR Studio

Geotecnico Italiano Srl, Milano(SGI-MI) X X X X

Aristotle University ofThessaloniki (AUTH)

X X X X

Istituto Nazionale di Geofisicae Vulcanologia, Roma (INGV)

X X

Kandilli Observatory andEarthquake Research Institute,

Istanbul (KOERI)X X X X


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SHAKING SCENARIO

on local soil:

ground motion parameters,

time histories

1D, 2D or simplified analysis of

ground response

Geological/Geotechnical Site

Conditions (Soil Type, Layer

Thickness, GWL, Vs Profile,

Dynamic Soil Properties)

VULNERABILITY CURVES

DAMAGE SCENARIO

At district level

RepairRate/Km

PGV, PGS, PGD

Selection of scenario

earthquakes

Probabilistic /Deterministic

Shaking Scenario on Bedrock

Outcrop (Peak values, or Time

Histories)

IS

InventoriesStructural response

of pipe mains

Identification of damaged

pipe sections

SHAKING SCENARIO

on local soil:

ground motion parameters,

time histories

1D, 2D or simplified analysis of

ground response

Geological/Geotechnical Site

Conditions (Soil Type, Layer

Thickness, GWL, Vs Profile,

Dynamic Soil Properties)

VULNERABILITY CURVES

DAMAGE SCENARIO

At district level

RepairRate/Km

PGV, PGS, PGD

Selection of scenario

earthquakes

Probabilistic /Deterministic

Shaking Scenario on Bedrock

Outcrop (Peak values, or Time

Histories)

IS

InventoriesStructural response

of pipe mains

Identification of damaged

pipe sections

Figure 11.1 Flowchart of the SP11 method.

Year 1 of the project saw the selection of cities forwhich damage scenarios were to be produced: inaddition to Thessaloniki and Istanbul, Dzce(Turkey) constituted a case history of real interestdue to the damage caused by the 1999earthquakes. KOERI, AUTH and SGI-MI worked

for the compilation of a dataset including theinventory of lifelines in the reference cities(including Catania, Italy, not further analysed),which has been collected in Deliverable D88,which is available from www.LESSLOSS.orgalong with all other deliverables produced in thisSub-Project.

Efficient computer codes for seismic wavepropagation in heterogeneous media, directlydeveloped by a partner or by other researchgroups in the previous European projects (asRISK-UE), were used by INGV to produce

numerical simulations of earthquake groundmotion over the urban area of Thessaloniki andIstanbul. Maps of peak ground velocity anddisplacement were produced for the scenarioearthquakes, and a first technical report on thisactivity released (Deliverable D83). During the 2ndyear much refinement in this work has been done.INGV produced new scenarios for bedrock motionfor Thessaloniki and Istanbul. With such referenceground motion, AUTH and KOERI have calculatedthe surface response within the selected cities,taking into account the local soil profile and using1D numerical models. SGI-MI on his part has

performed advanced 2D seismic responseanalyses along representative cross-sections inThessaloniki and Dzce (in the latter case with acombined model that includes the 1999

earthquake source). In addition to those of peakground parameters, also distributions of peak transientground strains (PGS) have been obtained, allowing touse vulnerability/damage curves as a function of PGS.The issue of earthquake generated ground strains hasbeen described in detail in Deliverable D87.

During the first year INGV, with the support of SGI-MI,has carried out the interpretation of aerial photo for theidentification of areas of potential soil instability in theCatania urban area, selected as a suitable applicationsite for this technique, with creation ofgeomorphological maps in GIS environment andsuperposition of these layers with the pipelinenetwork.

Regarding the simplified evaluation of transientground strains, SGI-MI developed a simplified formulato compute peak ground strains, based on fewparameters representative of subsoil conditions and

e.g. peak ground velocity. This activity encompassedthe first 2 years of the project, and the results weresummarised in Deliverable D87. In particular, duringthe 2nd year, the formula proposed has beenextensively validated against the results of the 2Dnumerical simulations and fully documented inDeliverable 116.

Numerical investigations for the evaluation andimprovement of existing vulnerability functions andtheir formulation either in terms of peak ground strainor peak ground velocity have been conducted mostlyat AUTH and, to a limited extent, at SGI-MI. A fullpicture of the tools developed to evaluate thevulnerability and damage of pipelines, quay walls andtunnels under shallow cover is contained in


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deliverable D89, released in final form at the endof year 2.

Two computational tools devoted to the evaluationof the seismic response of buried pipes weredeveloped, i.e.: At city district level, Koeripipe, developed by

KOERI, is a software tool developed forevaluating damage scenarios for pipelinenetworks, based on the approach adopted bythe software KoeriLoss2 that operatesthrough Geo-cell systems over GIS layers forevaluating the urban building damagescenario. It is fully described in the devotedDeliverable 118.

At the single pipe stretch level, Seismipipe,developed at SGI-MI, is a computer codewhich performs a FE analysis of a singlepipeline supported by springs that simulatethe reaction of the surrounding soil.

The damage scenarios for selected citiesconstitute an important outcome of the project. Adamage scenario for the water and gasdistribution systems of Thessaloniki has beendeveloped by AUTH, and for Istanbul and Dzceby KOERI. More detailed analyses were carriedout on Dzce by SGI-MI.

Activity in the third year of SP 11 saw thecompletion of the earthquake shaking scenariosfor Thessaloniki, Istanbul and Dzce by INGV. ForThessaloniki, the shaking parameters obtained

from 1D propagation analyses were compared byAUTH with the results obtained from theMicrozonation study performed in the metropolitan

Documents

4-LESSLOSS-Publishable Final Activity Report