29 gis seismic

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GIS-Based Monitoring of Seismic Vulnerability for a Class of ConcreteStructures during Lifetime Serviceability

Gabriela M. ATANASIU

PhDProfessorGh Asachi TechnicalUniversity of Iai, RomaniaFaculty of Civil EngineeringBd. D. Mangeron 43, 700050,Iai, Romania

E-mail: [email protected]

[email protected]

G. M. Atanasiu is a Professor inthe Department of Structural

Mechanics within the Faculty ofCivil Engineering andArchitecture, since 1995, and aPhD Supervisor since 1999. Sheis also Vice Dean and her mainresearch areas are: Modelingand Simulations in StructuralDynamics and Performance-based Earthquake Engineering.

Florin LEONPhD

LecturerGh Asachi TechnicalUniversity of Iai, RomaniaFaculty of Automatic Controland Computer ScienceBd. D. Mangeron 53, 700050,Iai, RomaniaE-mail: [email protected]

F. Leon is a Lecturer in theDepartment of ComputerScience and Engineering since

2006, and his main researchinterests are: artificialintelligence, simulations usingintelligent agents and datamining.

Dan GLEAPhDProfessorGh Asachi TechnicalUniversity of Iai, RomaniaFaculty of Automatic Controland Computer ScienceBd. D. Mangeron 53, 700050,Iai, RomaniaE-mail: [email protected]

D. Glea is a Professor in theDepartment of ComputerScience and Engineering, and aPhD Supervisor. His main

research areas are: artificialintelligence, knowledge-basedgeographical systems, imageprocessing, and naturallanguage processing.

Summary

This paper presents a methodology for GIS-based monitoring of the seismic performance, while

taking into account the deteriorations revealed during GIS-based scenarios aiming at theidentification of the seismic serviceability of the structure. The concept and methodology of usingtools of Spatial Information System are described along with the corresponding scenarios ofmodeling, simulation and nonlinear seismic analysis applied to a class of damaged models for someof the RC structure typical of the existing urban infrastructure of Iai, Romania. Finally themanagement of GIS-based seismic vulnerability of existing concrete structure is presented as a toolfor awareness and mitigation of seismic effects of possible future events in the urban area.

KEYWORDS

Existing concrete structures, seismic vulnerability, geographical information systems (GIS)
mailto:[email protected]:[email protected]:[email protected]:[email protected]


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1. IntroductionThe earthquake loss estimation methodology is intended to provide local, state and regional officialswith the tools necessary to assess the risks from earthquakes. This will help them to prepare foremergency response and recovery. Traditional loss estimation methodologies performed since theearly 1970's can be characterized as stagnant: inventory data and geologic attributes were collected,

one or more scenarios were evaluated and a report was written. Emphasis was given to oneparameter over another based on what the author(s) considered the "controlling factor" and therewas no mechanism to carry out what-if-analysis to account for the inventory variability, the geo-hazard data accuracy, and the uncertainty in the overall approach [1].

A GIS-based software tool was meant to change this approach. Tailored for different audiences withdifferent needs, it uses a segmented modular approach which can be customized by the users in anyway they see fit with the timeline and budget constraints they may face. Faced with limitedresources and competing priorities, the decision-maker requires accurate and accessible informationwhen dealing with natural hazards matters. One of the greatest challenges in developing adequateinformation resources is interoperability, or the need to accommodate multiple users, data providers,hazard stages, scenario simulations, and mitigation goals [2]. The Spatial Information Infrastructureand Geographical (or Spatial) Information Systems are valuable tools to address these issues.

Romanians territory is located within one of the European area of strong ground-motions, beingthroughout centuries a place where earthquakes with intensity 7 on MSK scale or the magnitude onRichter scale more the 6 may have occurred.

After the initiative sponsored in 1995 by Directorate XII for Science, Research and Development ofthe European Commission sponsored since research aimed at the retrieval, processing analysis anddissemination of strong motion data generated by earthquake and collected from strong motionsnetworks and individual station in Europe a growing database in terms of digital records is nowavailable for research and information. The Romanian Institute of Soil Physics is also posted forpublic use sets of earthquakes occurred in Romania in a Seismic National Catalogue, published inthe Official Monitor of Romania [3].

Usually in seismic research, the level of local seismic risk in some potential risk area is evaluated

based on seismic hazard assessment using Cornell [4] procedure in terms of computed PGA of theearthquake for a certain Return Period and Uniform Probability Response Spectra (UHRS).

The development of GIS technologies coupled with the expanding of mobile laptops on one handand the emergency of preparedness to handle and manage the vulnerable infrastructures of existingurban sites on the other hand lead to the elaboration of a research based methodology for a prioriand post event management of seismic risk.

2. GIS for Seismic Risk MonitoringA fundamental principle of risk assessment is that risk due to natural hazards such as earthquakes,hurricanes and floods is location dependent. The process of risk assessment involves hazardassessment and vulnerability analysis. The probability of earthquake occurrence varies depending on

location, and local site conditions also play a vital role in determining the intensity of theearthquake. Zoning of hazard prone regions is a common practice. The vulnerability of buildings,other critical structures and population is dependent on their exposure to the hazard, which variesfrom location to location. The spatial characteristics of hazard and vulnerability justify theapplication of mapping and spatial technologies such as GIS in the risk assessment process.

A widely accepted definition of GIS is the following: A Geographical Information System is anorganized collection of hardware, software geographical data and personnel designed to efficientlycapture, store, update manipulate, analyze and display all forms of geographically referencedinformation [5]. However, the term GIS could also be used to refer to the technology involved incapturing, storing, manipulating and analyzing spatial information.

Spatial Information Infrastructure (SII) is the basis for a modern, efficient resource administration oflarge areas (e.g. a country), or smaller ones (e.g. a city). Management solutions based on SII have

been first introduced in economically developed countries: USA, Canada, Japan, and have beenlately adopted by the European Union in order to create a lifetime economic and social development


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of the whole continent [6].

Spatial Information Infrastructure can also be applied to a large city, such as Iai, Romania. In thiscase the digital map represents the digital cadastre of Iai city, in which all existing buildings areprecisely located. Starting from this digital cadastre, more information sets can be added, regardingurban networks, demographical indicators, seismic vulnerability of buildings etc. Thus, the resulting

Geographical Information System can be successfully used to carry on different managerial tasks atcity level [7].

Analysis and simulation of diverse seismic scenarios are also made in an integrated fashion, takinginto account all the information available in databases. For the analysis of earthquake effects, threehypotheses can be considered [1]: deterministic hazard an earthquake produced in a locationwhere previous events have been recorded, probabilistic hazard an earthquake produced in alocation statistically chosen from records of extended periods of time, respectively 100, 1000 or2500 years, and user-defined hazard an earthquake simulated in a location desired by the user,with defined Peak Ground Acceleration and response spectra maps.

Long before, while the event causing a disaster is still only a possibility in the unknown future,many potential disasters can be mitigated through thoughtful planning and careful design. Thanks toalert systems, we may get some minutes to days of warning when the event is imminent. This allows

time for preparations, which could include boarding up windows, storing food and water, orevacuation. When the event happens, the main concern is of course to survive through it, butimmediately afterwards the rescue and clean-up operations start. With that done, the reconstructionstarts. In the reconstruction after an event one would naturally consider mitigation measures for thenext one [8].

GIS support may be used for all the disaster prevention phases, but what we are concerned with hereis the use of GIS for physical planning in the mitigation phase, so as to take the disaster risk intoconsideration as a fundamental property of the land [9]. This includes assigning appropriate landuse, defining building codes for that land use, and providing shelter facilities and evacuation routes.

3. Methodology Description of Digital Management of Seismic Urban RiskThe whole process of digital management for the vulnerability of constructions in built urbanenvironment is an integrated activity with multidisciplinary features, involving civil engineers aswell as architects, IT administrators, and the public administration sector.

The strategic objective of this process addresses the following purposes:

P1 vulnerability assessment of existing infrastructure for planning the preventive measuresof human safety against earthquake, as it has been proposed in the application of GIS tourban Northern Caucasian regions [10];

P2 creating instruments for the emergency management of situations based on a possibleseismic scenario;

P3 education goals for enhancing the social culture in crises management during and postcatastrophic events;

P4 building of safety patterns to seismic hazard in various urban samples, which will leadto a Digit City Map for evaluation of seismic vulnerability.

This complex program needed a strategic planning for the methodology of GIS-based managementof seismic urban risk. Such a planning has been initially set up by Atanasiu and Glea [6]. Theresearch presently goes on in a Postdoctoral Program supported by Ministry of Education andResearch of Romania within the Excellence Program CEEX developed between 2005 and 2007[11].

Research has begun so far on an urban sample of Iai municipality, a city with about 360000inhabitants with a complex urban structure of constructions, from historical monuments as churchesand castles from the 15

th 20

thcenturies to residential multi-floor buildings over 40 years of

functionality, critical facilities, one-storey residential old houses over one hundred years, etc. Thisurban area experienced only in the last century, sometimes almost without any repairs, two strongground motions over 7 in magnitude on the Richter scale and an important number of moderate


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earthquakes under 6 in magnitude due to still ongoing tectonic activities in the Vrancea area of theRomanian Carpathians. Our research is aiming to address the following activities:

Extraction of a significant urban sample, considered as pilot for procedure implementationfrom a GIS based city map;

Building the first database called STRUCT, an inventory based on available information onexisting classes of constructions including initial design information, life-cycle data onexisting constructions and facilities, soil data concerning the geology and geomorphology ofthe soil, local seismology information, data on earthquake resistance factor rdetermined byexperts in their reports in agreement with the Romanian seismic code [12] for theconstructions located in the pilot urban sample;

Clustering the obtained database upon the structural class affiliation of constructions, type ofstructural critical state of damageability, social, economic and historical importance;

Development of a second database named EMERGSAFE using GIS which includes allinformation on first aid in case of emergency (fire department locations, hospital locations,positioning of critical gas and electric facilities, or other important critical equipment in thecity, information on transportation etc.);

Implementation of a tool for city emergency management at the disposal of interested publicor private stakeholders.4. Implementation of Monitoring SchemeFollowing our objective of preventing the effects of the disasters on peoples safety from a densepopulated urban area, we choose from the digital map of the city presented in Fig. 1, a genericsample which includes a significant number of different classes of constructions and criticalfacilities. Fig. 1 is a digital map of Iai, the second largest city of Romania, located in the North-Eastern part of the country.

Fig. 1 A digital map of Iai City Fig. 2 A specific urban sample of the analyzedbuildings

A brief inventory of the modern part of Iai coupled with information from technical expert reportsshows that in the Central and South-Eastern part of the city a set of different classes of structures,having mostly residential destinations are considered in the first, second and respectively third stageof emergency state on the latest list of existing damaged buildings. Analyzing the structuralcharacteristics and material type of construction, these buildings are grouped in the following maincategories: shear wall buildings, reinforced concrete frame structures, and masonry structures.

This selected urban sample is shown in Fig. 2. One of the most vulnerable classes of structure is the

class of prefabricated shear wall with a typical topology of ground floor and fourth level, build after1965. One of the typical structures existing in the analyzed urban sample is shown in Fig. 3. Themethodology we used for vulnerability assessment described previously consisted of finite element


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modeling of the building and the spectrum response analysis for two cases of peak groundacceleration PGA of 0.5g and 1g respectively. The results concerning the period of vibration for twostages of the modeling: a-priori designed model (as a new structure) and the model obtained on realexisting damaged structure are presented in Table 1, and the results of stress analysis given inresponse spectrum method are illustrated in Fig. 4.

Table 1. Results of the modal analysis using SAP 2000

OutputCase StepType StepNum Period Frequency CircFreq Eigenvalue

Text Text Unitless Sec Cyc/sec rad/sec rad2/sec2

modal Mode 1 0.410182 2.4379E+00 1.5318E+01 2.3464E+02

modal Mode 2 0.381126 2.6238E+00 1.6486E+01 2.7178E+02

modal Mode 3 0.291611 3.4292E+00 2.1546E+01 4.6425E+02

modal Mode 4 0.154651 6.4662E+00 4.0628E+01 1.6506E+03

modal Mode 5 0.136173 7.3436E+00 4.6141E+01 2.1290E+03

The shear wall has usually a height of 2.8 m, a span between 3 m and 5.40 m, a thickness rangebetween 0.12 m and 0.25 m. The corresponding concrete resistance class is C16/20, according to

Romanian Code [12].

Fig. 3 Initial model of the building Fig. 4 Damaged structure response S22 stressstate for seismic analysis

Using the global damage index recommended by DiPasquale and Cakmak [13], we can assess thedamageability index of the structure which is in our case:

(1)

Taking into account the scale of damageability presented in IDARC [14], one can assess that thisstructure belongs to the class ofSevere Degree of Damage, withDIbetween 0.4 and 1.0.

Applying GIS technology, the results of the diagnosis presented is visualized on the digital map ofseismic vulnerability for the analyzed urban sample and the methodology will be extended for thewhole class of buildings belonging to the same topology cluster.

5. ConclusionsThe present paper highlights our concept of vulnerability assessment in a deterministic manner foran existing infrastructure in big urban sites, exposed repeatedly to a various range of earthquakesand lack of continuous maintenance measures during life cycle serviceability of a building. The

methodology of vulnerability assessment is illustrated on a representative pilot structure selectedfrom the urban sample of existing damaged infrastructure. Using GIS technology, by generalization,

439.0

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the digital map of seismic vulnerability can be built, which is useful for the risk management ofcities requested by various stakeholders of local and national importance. This paper presentedpartial results of the implemented methodology in an on-going stage, the whole study being underdevelopment using a statistical approach.

6. References[1] Bouhafs M., Si C., Lawson R. S., Bouabid J., GIS implementation of a nationwide seismic

risk assessment methodology, ESRI International Users Conference, Paper 375;http://www.esri.com/library/userconf/proc97/proc97/to400/pap375/p375.htm, 1997.

[2] Wood, N., Stein D., A GIS-based vulnerability assessment of Pacific Northwest ports andharbors to tsunami hazards,ITS 2001 Proceedings, Sessions 1, Number 1-13, pp. 367-374.

[3] Official Monitor of Romania, No. 1221 bis / Dec. 2004.[4] Cornell, C.A., Engineering Risk analysis,Bulletin of the Seismological Society of America,

58 (5), pp. 1583-1606, 1968.

[5] Lavakare A., Krovvidi A., GIS & Mapping for Seismic Risk Assessment,National seminaron Habitat Safety against Earthquakes and Cyclones, New Delhi, May 2001.

[6] Atanasiu G., Glea D. (ed.), GIS monitoring of urban seismic risk, Politehnium, Iai,Romania, 2005.

[7] Glea D., Leon F., et al., Knowledge-Based Geographical Systems, Bulletin of TechnicalUniversity of Iai, tome XLIX (LIII), fasc. 1-4, pp. 81-94, 2003.

[8] Godschalk D.R., Beatley T., Berke P., Brower D.J., Kaiser E.J., Natural Hazard Mitigation:Recasting Disaster Policy and Planning,Island Press, Washington, 1999.

[9] Erlingsson U., GIS for Natural Hazard Mitigation: Experiences from designing the HazMitGIS expert system suggests the need for an international standard, GIS Planet 2005,Portugal, http://erlingsson.com/ authorship/conf/GISforNatHazMit.pdf.

[10] Shakhramjyan M.A., Nigmetov G.M., et.al., GIS Application for vulnerability and seismicrisk assessment for some Northern Caucasian Cities, in Invited lectures within Proc. of the

Eleventh European Conference on Earthquake Engineering, Paris 1998, Balkema A.A.,pp.351-361, 1999.

[11] Atanasiu G.M., Leon F., Spatial Infrastructure Information (SII) Based Management forSeismic Vulnerability of Built Urban Fund, Research Report Grant 3202, CEEX Program,2005-2007, supported by the Romanian Ministry of Education and Research, 2006.

[12] ***, Romanian Code for Seismic Design of Residential Buildings, Agro-zootechnical andIndustrial Structures, Chapter 12, Provisions concerning the intervention on existingbuildings, P100-92, English Edition, Ministry of Public Works and Territory Planning,Romania, 1992.

[13] DiPasquale E., Cakmak A.S., On the relation between local and global damage indices,Technical Report NCEER-89-0034, Princeton University, 1989.

[14] Valles R.E., Reinhorn A.M., et al., IDARC 2D Version 4.0: A Program for the InelasticDamage Analysis of Buildings, Technical Report NCEER-96-0010, State University of NewYork at Buffalo, 1996.
http://erlingsson.com/http://www.esri.com/library/userconf/proc97/proc97/to400/pap375/p375.htm,

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