ASSESSMENT OF DAMAGE AND USABILITY OF EARTHQUAKE-DAMAGED BUILDINGS: EXPERIENCE OF SLOVENIA

1. ASSESSMENT OF DAMAGE AND USABILITY OF EARTHQUAKE-DAMAGED BUILDINGS: EXPERIENCE OF SLOVENIA Miha Tomaževič Slovenian National Building and Civil Engineering Institute Milica Slokar Administration of Civil Protection and Disaster Relief of the Republic of Slovenia

2. Seismic risk in Slovenia • 1/3 of the population of Slovenia is concentrated inregionswhereearthquakes with PGA = 0,2 g and more are expected with return period of 475 years. • In Ljubljana region, the most densely populated area of the country, where the basic functions of the countryareconcentrated, seismic hazard is even more severe. • Most of the damage and casualties are due to inadequate seismic behaviourof existing buildings. The existing building stock (mainly unreinforced masonry buildings) is estimated to be almost 50% of the total.

4. Castles Urban architecture Rural architecture Typical heritage masonry buildings in Slovenia

5. Pre-1963 unreinforced masonry tower houes Pre-World War II buildings Typical pre-seismic codes masonry residential buildings in Ljubljana

6. 1895: the earthquake of Ljubljana 1931-33: the skyscraper of Ljubljana - base isolation 1963: seismic design recommendations 1964: first Yugoslav seismic code 1981: revised Yugoslav seismic code 1995: Eurocode 8, ENV version translated as alternative 2008: Eurocode 8 mandatory History of seismic codes Existing buildings 1978: law on seismological service 1985: Yugoslav code for repair and strengthening of earthquake-damaged buildings 2008: Eurocode 8-3 Assessment and strengthening of buildings mandatory

7. Experience in earthquake-damage assessment • 1974: Kozjansko RegionGovernmental committee for damage evaluation.4 categories of damage • 1976: Friuli earthquakes. Posočje RegionGovernmental committee for damage evaluation. 3 categories of damage, 3 categories of usability • 1998: Upper Posočje RegionACPDR. 5 categories of damage, 3 categories of usability. Categories of damage compatible with definitions given in EMS scale • 2004: Upper Posočje Region

8. Assessment of usability and damage • Rapid evaluation:To assess usability of buildings and provide information regarding the safety of occupancy and assess the number of inhabitants needing temporary shelters • Detailed evaluation:To provide detailed information regarding the damage to buildings, which can be used as a basis for the assessment of damage costs

9. Pages 2 and 3 of questionnaire for usability and damage assessment

10. GIS-UJME Applications Address search, number of inhabitants calculation

11. Damage category 1: negligible to slight damage • Damage category 2: moderate damage • Damage category 3: substantial to heavydamage • Damage category 4: very heavy damage • Damage category 5: partial or total collapse Classification of damage to masonry buildings as defined by EMS scale

12. Classification of usability • Usable buildings • Temporarily not usable buildings • Unusable buildings

13. Classification of usability Usable buildingsmarkedgreen Restriction: Building occupancy may continue without limitation Damage category 1 and 2 : Undamaged buildings Slight structural damage Moderate non-structural damage

14. Classification of usability Temporarily not usable buildingsmarkedyellow Restriction: Occupancy may continue if the safety can be ensured by emergency safety measures. In most cases, the occupancy is not possible until the building is completely repaired and strengthened Damage category 3: Substantial damage to structural system Heavy non-structural damage

15. Classification of usability Unusable buildingsmarkedred Restriction: Unusable, unsafe buildings are demolished and the debris removed Damage category 4 and 5: Heavy structural damage, very heavy non-structural damage Total or near total collapse

16. Assessment procedure UsabilityAssessment Commission is usually composed of 2experts and local guide, who assess 20 –30 buildings per day (rapid assessment). For easier identification of buildings, special municipality maps in seismic-prone areas of Slovenia have been prepared by ACPDR. Municipalities are divided into several zones, each including approximately 100 buildings. Each zone is limited by natural or physical objects (streets, rivers, etc.).

19. The case of the earthquake of Bovec of April 12, 1998 • Based on the information received from local staff of Civil Defence, ACPDR immediately mobilised 25 professionals, who inspected the damaged buildings and assessed their usability according to the proposed methodology • Only buildings with permanent residents and some cultural monuments have been included in the rapid evaluation of damage and usability. Four days have been needed to complete rapid evaluation. 952 buildings have been inspected. • 311 buildings have been found as temporarily not usable. Among them, 1/3 have been seriously damaged, in some cases even beyond repair, and 2/3 have suffered repairabledamage. More than 710 people have been temporarilymovedto mobile homes, located close to their homes.

20. Experience after the earthquake of 1998 • Timely and constant training of professionals, who will be mobilised in the case of an earthquake disaster, for both usability assessment and damage evaluation, is needed. Otherwise, significant delays inearthquake disaster mitigation activities can be expected • Therefore, within the earthquake preparedness program of Slovenia, prepared by ACPDR, a continuous training of experts, members of committees for the assessment of damage and usability of earthquake damage buildings has been set forth

21. Experience after the earthquake of 1998 • First exercise has been organized during a simulation of an earthquake disaster, carried out in Ljubljana in 1999 • In 2001, the members of committees for the assessment of damage and usability of earthquake damage buildings have been educated during courses organized in the ACPDR’s the training centre. In the years to follow, the knowledge has been improved by practical exercises on earthquake- damaged buildings on the site • About 200 professionals have been trained so far

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