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# 15WCEE_620_Craifaleanu&Borcia

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Presentation at the 15th World Conference on Earthquake Engineering (2012) of paper no. 620: Craifaleanu, I. G., Borcia, I. S., "Damage Index vs. Instrumental Intensity: A Comparison of Two Different Approaches in Seismic Damage Assessment"

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### 15WCEE_620_Craifaleanu&Borcia

1. 1. DAMAGE INDEX VS. INSTRUMENTAL INTENSITY: A COMPARISON OF TWO DIFFERENT APPROACHES IN SEISMIC DAMAGE ASSESSMENT Iolanda-Gabriela CRAIFALEANU Technical University of Civil Engineering Bucharest, Romania & National R&D Institute “URBAN-INCERC”, INCERC Bucharest Branch i.craifaleanu@gmail.com, iolanda.craifaleanu@utcb.ro Ioan Sorin BORCIA National R&D Institute “URBAN-INCERC”, INCERC Bucharest Branch isborcia@incerc2004.com, isborcia@yahoo.com
2. 2. PPT available at:Iolanda-Gabriela CRAIFALEANU, Ioan Sorin BORCIADAMAGE INDEX VS. INSTRUMENTAL INTENSITY:A COMPARISON OF TWO DIFFERENT APPROACHESIN SEISMIC DAMAGE ASSESSMENTDEFINITIONSINSTRUMENTAL INTENSITY – intensity based on destructiveness spectrum (Sandi, 1987, Sandi et al., 1998) ( ) i d (ϕ) = log7,5 ∫ w a (t , ϕ, 0,05 ) dt + 6,45 2 wa(t, ϕ, ξ) = (absolute) acceleration (m/s2) for a pendulum of nat. freq. ϕ (Hz); ξ = damping ratio id(ϕ) is calibrated to match the values of the EMS-98 intensity scale to assess the destructiveness on separate frequency bands, id(ϕ) was averaged upon spectral bands, (ϕ, ϕ")   dϕ   i d * (ϕ , ϕ" ) = log7,5  1 ( ln(ϕ" , ϕ) ∫  ∫ ) w a (t, ϕ, 0,05 ) dt 2 ϕ   + 6,45   PARK-ANG DAMAGE INDEX (Park & Ang, 1985) ( DM ⋅ µ mon = µ max + β E H Fy u y ) EH = hysteretic energy; Fy = yield strength; uy = yield deformation; β = constant depending on structural characteristics, mon = monotonic ductility, max = max. ductility DM = 0.2 upper limit of insignificant damage; DM = 0.5 upper limit of repairable damage; DM= 0.5…1.0 severe, non-repairable damage; DM > 1.0 occurrence of structural collapse In the study, DM was computed for specified values of mon and of Cy=Fy/G DM values were averaged on the same spectral intervals as id(ϕ)
3. 3. PPT available at:Iolanda-Gabriela CRAIFALEANU, Ioan Sorin BORCIADAMAGE INDEX VS. INSTRUMENTAL INTENSITY:A COMPARISON OF TWO DIFFERENT APPROACHESIN SEISMIC DAMAGE ASSESSMENTINSTRUMENTAL INTENSITY & P-A INDEX DAMAGE MAPS AUGUST 30, 1986 VRANCEA EARTHQUAKE (Mw = 7.1, h = 133 km) Maps of values averaged on the T=0.35…0.5 s spectral band Park-Ang Instrumental damage index intensity Cy=0.20, µmon=6Spectral bands Spectral bands 0.25…0.35s 0.25…0.35s 0.35…0.50s 0.35…0.50s 0.50…0.70s 0.50…0.70s 0.70…1.00s 0.70…1.00s
4. 4. PPT available at:Iolanda-Gabriela CRAIFALEANU, Ioan Sorin BORCIADAMAGE INDEX VS. INSTRUMENTAL INTENSITY:A COMPARISON OF TWO DIFFERENT APPROACHESIN SEISMIC DAMAGE ASSESSMENTANALYSIS OF DAMAGE FOR CHARACTERISTIC BUILDING TYPOLOGIES The study was performed with Structural Structure No. of Height Code Typology reference to the 30.08.1986 Vrancea system type stories (stories) level code earthquake R.C. frames RC3.1 4…7 MR LC RC3.1-MR-LC with regular MC RC3.1-MR-MC Building typologies: blocks of flats, unreinforced 8…10 HR LC RC3.1-HR-LC masonry based on standard designs, infill walls MC RC3.1-HR-MC 1963 – 1986 Concrete RC2 4…7 MR LC RC2-MR-LC shear walls MC RC2-MR-MC 1960 -1977: > 90% of the new constructed residential buildings 8…10 HR LC RC2-HR-LC were based on standard designs MC RC2-HR-MC …1989 Precast RC5 4…7 MR LC RC2-MR-LC concrete MC RC2-MR-MC today: standard blocks of flats = tilt-up walls 8…10 HR LC RC2-HR-LC major part of the urban housing (Precast panels) MC RC2-HR-MC stock in Romania Seismic intensity according to Romanian code: 12 reinforced concrete structure City typologies, based on RISK-UE P13-63* P13-70 P100-78 typologies (Mouroux & Brun, 2006) Bucharest 7 7 8 Barlad 8 8 8 Analysis for 3 representative cities in Focsani 9 9 9 Romania P13-63: first compulsory seismic code in Romania (1963) P13-
5. 5. PPT available at:Iolanda-Gabriela CRAIFALEANU, Ioan Sorin BORCIADAMAGE INDEX VS. INSTRUMENTAL INTENSITY:A COMPARISON OF TWO DIFFERENT APPROACHESIN SEISMIC DAMAGE ASSESSMENTANALYSIS OF DAMAGE FOR CHARACTERISTIC BUILDING TYPOLOGIES Instrumental Bucharest, Focsani,INSTRUMENTAL INTENSITY APPROACH intensity INCERC, NS Hotel, EW Id component component Class EMS-98 Damage assessment based on the Bucharest Vulnerab. P100-78 P100-78 Focsani P13-63 P13-70 P13-63 P13-70 Structure Typology averaged intensity values (rounded to type code the nearest integer*), according to vulnerability classes in EMS-98 R.C. frames RC3.1-MR-LC D 7.45 8.01 1F 1F - 2F 2F - with regular RC3.1-MR-MC E 1F 1F - 2F 2F - * this led to uniform damage values in the unreinforced RC3.1-HR-LC D 1F 1F - 2F 2F - adjacent table masonry RC3.1-HR-MC E 7.39 8.06 1F 1F - 2F 2F - infill walls Buildings designed according to R.C. shear RC2-MR-LC D 6.93 8.15 1F 1F - 2F 2F - walls RC2-MR-MC E 7.15 8.33 1F 1F - 2F 2F - P13-63 and P13-70 codes: RC2-HR-LC D 7.46 8.39 1F 1F - 2F 2F - a few buildings in Bucharest would RC2-HR-MC E 7.45 8.01 1F 1F - 2F 2F - Precast R.C. RC2-MR-LC D 6.93 8.15 1F 1F - 2F 2F - suffer grade 1 damage (1F) 1F) tilt-up walls RC2-MR-MC E 7.15 8.33 1F 1F - 2F 2F - a few buildings in Focsani would suffer (Precast RC2-HR-LC D 7.46 8.39 1F 1F - 2F 2F - panels) grade 2 damage (2F) 2F) RC2-HR-MC E 7.46 8.39 1F 1F - 2F 2F - “F” = few and “M” = many buildings, as defined by EMS-98 Buildings designed according to P100-78 code: Pros: satisfactory agreement with Pros: satisfactory agreement with no damage would occur actual recorded damage actual recorded damage for the considered ground motions Cons: values not sufficiently Cons: values not sufficiently differentiated according to structure differentiated according to structure type type
6. 6. PPT available at:Iolanda-Gabriela CRAIFALEANU, Ioan Sorin BORCIADAMAGE INDEX VS. INSTRUMENTAL INTENSITY:A COMPARISON OF TWO DIFFERENT APPROACHESIN SEISMIC DAMAGE ASSESSMENTANALYSIS OF DAMAGE FOR CHARACTERISTIC BUILDING TYPOLOGIES DAMAGE INDEX APPROACH Alternative (inverse) approach: Alternative (inverse) approach: assessment of the overstrength assessment of the overstrength DM = (1/ mon) ( max+β (EH/(Fyuy)) factors required to limit factors required to limit where damage at specified levels damage at specified levels Fy = Cy G = (Cs ROVS) G ROVS = Cyy//Cs s ROVS = C C Cs = design base shear coefficient Applications: (code-specified) ROVS = structural overstrength factor Assessment of the actual overstrength of structures during an earthquake, by inputting DM The assessment of DM for buildings values corresponding to with known Cs requires also knowing observed damage the value of ROVS Assessment of the required As ROVS is difficult to estimate a priori overstrength associated with alternative approach characteristic damage levels (insignificant: DM=0.2, repairable DM=0.4…0.5, collapse DM=1)
7. 7. PPT available at:Iolanda-Gabriela CRAIFALEANU, Ioan Sorin BORCIADAMAGE INDEX VS. INSTRUMENTAL INTENSITY:A COMPARISON OF TWO DIFFERENT APPROACHESIN SEISMIC DAMAGE ASSESSMENTANALYSIS OF DAMAGE FOR CHARACTERISTIC BUILDING TYPOLOGIES DAMAGE INDEX APPROACH Overstrength factors required to limit damage at specified levelsActual damage in Bucharest on 30.08.1986: Heavy cracking in partition Bucharest, Focsani, Structural DM=0.2, mon = 8 DM=0.5, mon = 4 walls for some medium- and system Typology ROVS for buildings ROVS for buildings high-rise reinforced concrete designed according to: designed according to: frames designed according to P13-63 P13-70 P100-78 P13-63 P13-70 P100-78 R.C. frames RC3.1-MR-LC 3.9 4.4 2.7 4.6 P13-63 and P13-70 with regular RC3.1-MR-MC 1.6 2.7 consistent with the assumed unreinforced RC3.1-HR-LC masonry infill 3.3 3.8 1.4 2.4 DM values and with previous walls RC3.1-HR-MC 1.4 1.4 analyses on actual R.C. shear walls RC2-MR-LC 1.7 1.7 1.4 2.1 overstrength RC2-MR-MC 1.1 2.2 Practically no damage was RC2-HR-LC 3.4 2.6 2.3 2.7 RC2-HR-MC 1.4 2.3 recorded in shear wall Precast R.C. RC2-MR-LC 2.2 1.8 1.8 2.2 structures suggests that they tilt-up walls RC2-MR-MC 1.2 2.6 have met the overstrength (Precast panels) RC2-HR-LC 2.4 2.0 1.8 2.2 requirements imposed by the RC2-HR-MC 1.4 2.6 earthquake Similar interpretation for Focsani
8. 8. PPT available at:Iolanda-Gabriela CRAIFALEANU, Ioan Sorin BORCIADAMAGE INDEX VS. INSTRUMENTAL INTENSITY:A COMPARISON OF TWO DIFFERENT APPROACHESIN SEISMIC DAMAGE ASSESSMENTCONCLUSIONS INSTRUMENTAL INTENSITY APPROACH Pros: satisfactory agreement with actual recorded damage Cons: does not allow sufficient differentiation of results according to seismic code (level of seismic design forces) structure type DAMAGE INDEX APPROACH Pros: allows assessment of actual/required structural overstrength, if seismic design level is known, in the alternate (inverse) approach Cons: in the direct approach, damage assessment requires prior evaluation/specification of structural overstrength and of monotonic ductility The work reported in the presentation was partly sponsored by the Romanian National Authority for Scientific Research, ANCS