Seismic fragility curves for RC buildings and bridges in Thessaloniki

Transcription

1 Seismic fragility curves for RC buildings and bridges in Thessaloniki Georgios Tsionis, Joint Research Centre, ELSA (formerly University of Patras) Michael N. Fardis, University of Patras, Greece

2 Typologies Effects of design to EN-Eurocodes of RC on buildings the seismic fragility and of concrete bridges buildings 6.80% 3% Buildings \\\\\\\\\\\ 10% Bridges 13% 33% 93.17% Dual Infilled frames Pilotis 17% 37% 27% Deck with joints; bearings Single-span; bearings Cont. deck; bearings Cont. deck; fixed connection Cont. deck; fixed & bearings 33% Low-, mid-, high-rise Low-, medium-, high-level of seismic design 30% < > 1993

3 Fragility analysis Intensity measure: peak ground acceleration (PGA) Damage grades: yielding, ultimate Damage measures: chord rotation and shear force of beams, columns, walls and piers; deformation of bearings Buildings: regular prototype design to 1959 or 84 code or to EC8 Bridges: real ones (geometry, reinforcement & material properties from design drawings) Fragility: conditional -on PGA- probability that demand> capacity Mean demand from static analysis per EC8-3: elastic response spectrum, mean material properties, secant-to-yield stiffness; rigid deck model or modal analysis for bridges Mean values of capacity: from EC8-3 formulas; Coefficients of variation for demand and capacity: model & geometry uncertainties, dispersion of material properties.

4 Frame buildings: low- v high-rise; effect of design code Yielding Ultimate Yielding Ultimate Design PGA Pilotis Pilotis >1984 Infilled Infilled >1984 Pilotis: minor damage at design PGA Smaller margin between damage states for older buildings Lower fragility of taller buildings Lower fargility for infilled frames

5 Wall-frame buildings, low- v high-rise; design code Design PGA Yielding Ultimate Largest group in typology > EC Walls more critical than beams or columns at both damage states High probability of yielding at wall base under design PGA Seismic design to more modern codes: lower probability of reaching ultimate.

6 1.0 Single-span bridges on bearings B11 Shear L Shear T Rollover L Rollover T B Length: 20 m 1990 Length: 13.4 m B14 B Length: 40 m 1994 Length: 20.3 m Fragility curves are greatly influenced by the basic geometry of bridges belonging to the same structural type and designed with the same seismic code

7 1.0 Multi-span, Effects of design to EN-Eurocodes continuous the seismic deck fragility on of concrete bearings buildings B Pier ultimate Bearings Bridge B17 B17 B17 Pier ultimate Bearings Bridge 2002 B06 B06 B06 B06 Pier 1 L Pier 1 T Pier 2 L Pier 2 T Pier 3 L Pier 3 T Pier 4 L Pier 4 T Yielding Pier 5 L Pier 5 T Ultimate 1.0 Low probability of damage at the design PGA Bearings are critical for the ultimate state Bearings may fail before yielding of the piers Better seismic design improves the performance of piers more than that of bearings

8 Fixed deck-pier connection 1.0 B04 B19 Pier ultimate B04 Pier ultimate Pier 1 L Pier 1 T Pier 2 L Pier 2 T Pier 3 L Pier 3 T free transv. translation at abutments 1.0 Pier ultimate 1.0 B07 B07 B15 Fixed deck ends 1.0 B19 Free deck ends h = 6.2 m h = 11.4 m Pier ultimate Pier 1 L Pier 1 T Pier 2 L Pier 2 T B15 Pier 3 L Pier 3 T B04, B19: monolithic deckpier connection Negligible probability of damage at design PGA for modern bridges B07, B15: deck on bearings, fixed at central pier Short piers prone to shear failure Tall piers less vulnerable

9 Conclusions Most buildings are likely to suffer minor damage at the design PGA. Significant damage is expected only after twice that value. Most bridges have low probability of damage at the design PGA, but bearings in old bridges may fail. The fragility curves of bridges of a given structural type vary significantly with their basic geometry. The fragility curves were used in the validation study in Thessaloniki to: predict the extent of damage study the interaction between collapsed buildings and roads perform connectivity analysis of the road network estimate socio-economic consequences (shelter needs from damage to buildings and utility loss)