GMPV10

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EGU Vienna 2006

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GMPV10

  1. 1. Historical Structure Materials in Earthquakes Maria Bostenaru ROSE School / IUSS di Pavia, Italy
  2. 2. EGU GA 2006, Vienna Maria Bostenaru Overview  Scope  Case studies
  3. 3. EGU GA 2006, Vienna Maria Bostenaru Introduction  Historical construction materials =  Part of the construction characteristics worth to be preserved  Testimonials of the past in urban environments  Constructions of historic importance are affected by  aging of their construction materials (uniformly)  Natural catastrophes like earthquakes (non- uniformly)
  4. 4. EGU GA 2006, Vienna Maria Bostenaru Technologies, materials, practices  Histories of building industry, materials, know-how, labour and craftsmanship (trans)formed the theory, practice and conservation of architectures both over time and different geographical contexts  Continue to form the basis of the problem physically in conservation projects
  5. 5. EGU GA 2006, Vienna Maria Bostenaru Earthquake impact  Natural catastrophes (as earthquakes) have a non-uniform impact on  urban areas  individual buildings  The collapse mechanism is determinant for where the historical building fabric is most vulnerable.
  6. 6. EGU GA 2006, Vienna Maria Bostenaru load-bearing structure – architectural space  Morphological building systemic analysis 1. container: load-bearing scaffold, physical level 2. content: architectural space, phenomenological level  Functional building systemic analysis  perception – historical conscience  lived architectural space, door to it, scenography  Dynamic building systemic analysis  processuality  material stratification – historic multilayering
  7. 7. EGU GA 2006, Vienna Maria Bostenaru Spaces  ‘positive‘ matrix of surrounding physical elements which define the ‘negative‘ air volume of the space  The space bears history  educative effect in atmosphere perception related to function  materiality, subject of physical deterioration  Archaeology of the space (Libeskind)  image (mental) ≠ picture (physical)  The space opens to perception with all senses, movement and touch being essential.  Importance of materials and spatial-temporal parcours.
  8. 8. EGU GA 2006, Vienna Maria Bostenaru The role of structural materials  Tectonic: separation constructive structure (not visible) – ornament (visible)  Architecture = space, shape, function, material texture and surface  The load-bearing structure contributes to the quality of the interior over:  construction details  materials and finishings  dimensions  shapes – each maerial has its own shape (related to atmosphere and fabrication)
  9. 9. EGU GA 2006, Vienna Maria Bostenaru Framed load-bearing structures  Space-structure relationships 1. Structural space (material bound to shape, monolit) 2. Free plan (scaffold and elements separated) 3. ‘Raumplan‘ (function dictates)  Framed structures allow for all of them, while in masonry structures only 1 is possible.  Clothing theory of Semper: from ‘Gewand’ to ‘Wand’ elements: floor, wall, ceiling visualisation of applicative character, including infills, in different materiality with new technologies related to iron and concrete scaffolds/skeletons
  10. 10. EGU GA 2006, Vienna Maria Bostenaru Case studies  Timber frame  Region of the Alps (half-timbered buildings)  Portugal (Pombalino-buildings)  Iron/Steel frame  Germany (iron skeleton)  Iran (steel skeleton)  Reinforced concrete frame (Modern movement)  Romania  Greece  Italy
  11. 11. EGU GA 2006, Vienna Maria Bostenaru Timber frame load-bearing structures  Portugal  Pombalino-buildings  1755 – Lisbon earthquake  Region of the Alps  Fachwerk (half-timbered)  1356 – Basel earthquake
  12. 12. EGU GA 2006, Vienna Maria Bostenaru Fachwerk-buildings in the Alps zone  Timber characteristics structural element construction material characteristic strength mix proportion / dimensions infill adobe on basketry - clay (10%) + silt (clay with grain size 0.002-0.06mm) + sand + gravel. Often straw was added (chaffed). See www.fachwerkhaus.de 4-5 punts (oak, 3-5cm wide) were necessary for a infill- frame of about 1m width. frame (historic buildings) oak (sometimes fir) Elasticity modulus 70000-120000; Tension strength 1310 kg/cm² Compression strength 510 kg/cm² Bending strength 1020 kg/cm² Shear strength 79 kg/cm² frame (new buildings) douglas fir or laminated wood Elasticity modulus 72000-144000; Tension strength 250 kg/cm² Compression strength 1080 kg/cm² Bending strength 840 kg/cm² Shear strength - Threshold: 13/18(20, 21), 15/20, 16/21 cm Crossbar: 12/12(14), 13/13(15, 18) cm Corner post: 13/13(16), 15/15, 16/16, 21/21 cm Post: 12/12(14,16), 13/13(15,16) cm Struts: 12/16, 13/18 cm Frame: 12/16, 13/18, 16/21 cm (Stade, 1904) floors oak as above 2-5cm thick planks Joists: 2.5cm(0.80m span)-16cm(4.5m span) roof oak as above rafters 8/8 – 28/30 cm (Stade, 1904)
  13. 13. EGU GA 2006, Vienna Maria Bostenaru Pombalino-buildings seismic deficiency retrofit measure infill „out-of-plane“ danger connection deficiency (masonry-masonry and masonry to frame) steel/reinforced concrete beam at the top of the building Steel elements or ties, cables or anchors from wall to wall roof material deterioration of timber low strength connection to masonry steel rods, nails and bolts to strengthen timber element connections FRP strengthening floors SOURCE: R. Cardoso, M. Lopes, R. Bento, and D. D‘Ayala: „Historic, braced frame timber buildings with masonry infill (‚Pombalino‘ buildings)“, WHE report #92
  14. 14. EGU GA 2006, Vienna Maria Bostenaru Timber frame – Material comparison the Alps Portugal infill adobe calcareous masonry frame oak (sometimes fir) pine and oak roof oak pine and oak floors oak pine and oak
  15. 15. EGU GA 2006, Vienna Maria Bostenaru  Iran  2003 – Bam earthquake (Photo Hashemi et al) Residential buildings with iron or steel skeleton  Germany  1978 – Albstadt earthquake
  16. 16. EGU GA 2006, Vienna Maria Bostenaru Housing with steel skeleton in Iran seismic deficiencies earthquake resilient features earthquake damage patterns seismic retrofit infill unanchored walls sufficient in-plane stiffness > lateral resistance out-of-plane X cracking addition of concentric bracing frame soft storey sufficient storey shear resistance storey buckling addition of concentric bracing roof and floors insufficient roof support heavy, flexible roofs - total/partial collapse horizontal bracings welded on the roof/floor beams connections slippage between the girders and columns insufficient sitting width for the girders on the columns angel connections - excessive rotations shear failure of the welds unsitting strengthening of the connection confinement using steel plates AFTER: B.H. Hashemi and M.G. Ashtiany: „Semi-rigid steel frame with ‚Khorjinee‘ connections“, WHE report #26
  17. 17. EGU GA 2006, Vienna Maria Bostenaru Metal frames – Material comparison Germany Iran* infill holed brick brick frame iron steel roof iron stone reinforced concrete floors iron stone reinforced concrete * 3 different types (Source: BEE)
  18. 18. EGU GA 2006, Vienna Maria Bostenaru Reinforced concrete frame housing  Romania  1940 and 1977 – Vrancea earthquakes  Greece  1978 Thessaloniki 1999 Athens earthquakes infill clay brick frame (skeleton) RC roof RC floors RC
  19. 19. EGU GA 2006, Vienna Maria Bostenaru Reinforced concrete housing buildings  Romania seismic deficiencies earthquake resilient features earthquake damage patterns seismic retrofit infill some located on consoles of the façade. Collapse of façade infill can be fatal to building torsional equilibrium beneficial effect: increase the stiffness of the building strong rifts dislocation X rifts in piers Injecting adding structural walls columns do not form moment resisting frames with beams execution accidents (non-vertical, insufficient cement / reinforcement) - SOFT STOREY (svelte columns): concrete spalling, reinforcement buckling (short columns): brittle breaks at 45° affecting general stability CURRENT STOREY: horizontal rifts at plastic hinge, reinforcement buckling, concrete spalling, oblique rifts Pounding damage local repairing column jacketing
  20. 20. EGU GA 2006, Vienna Maria Bostenaru Reinforced concrete housing buildings  Romania (continued) seismic deficiencies earthquake resilient features earthquake damage patterns seismic retrofit beams do not form moment resisting frames with the columns; many of them at least in one direction secondary beams cement and reinforcement might be insufficient mostly executed and reinforced carefully LONG BEAMS: plastic articulation, rotation at plastic hinge with upper and lower rifts, concrete failure only at lower side SHORT BEAMS: oblique rifts: either brittle or opening the beam in the whole height upwards, sometimes buckling local repairing repairing with plating with woven glass embedded in epoxy resins beam jacketing roof and floors simple slab floors may be too elastic at over 4.5m span out-of-plane effects at execution errors cement and reinforcement may be insufficient when speculatively constructed Alternative solutions for slab rigidity (embeded holed bricks, waffle system) ROOM SLAB: few rifts BALCONIES: few rifts STAIRS: some more rifts at change of stair flights
  21. 21. EGU GA 2006, Vienna Maria Bostenaru Data organisation in the WHE Structural element Building materials Structural element Seismic deficiency Earthquake resilient features Earthquake damage patterns Seismic deficiency Seismic strengthening provision Characteristic strength Mix proportion/ dimensions
  22. 22. EGU GA 2006, Vienna Maria Bostenaru Comparison  Timber structures are less damaged by earthquakes and their construction material is thus less endangered  Steel/iron elements are also well preserved, eventually new retrofit elements are added  Reinforced concrete elements are usually largely by earthquakes. Reparation or retrofit measures of previously damaged buildings encompass important changes in the construction material  The preservation of the construction material is therefore very differentely shaped in case of the load-bearing structure of historic frame buildings and depends on the size of the earthquake and the material of the load- bearing structure.
  23. 23. EGU GA 2006, Vienna Maria Bostenaru Conclusions  Historical/archaeological testimonials of a construction time and of the construction technique of that time are endangered by:  damages induced by natural catastrophes  measures for  reparation of damages  preventive retrofit  The criterion of the monument protection „Maintenance of the urban historic fabric and with its buildings and their materials“ is to be fulfilled.
  24. 24. EGU GA 2006, Vienna Maria Bostenaru Sources  M. Bostenaru Dan: „Fachwerkhaus in Dreiländereck (Half-timbered hous)“, WHE report #98  R. Cardoso, M. Lopes, R. Bento, and D. D‘Ayala: „Historic, braced frame timber buildings with masonry infill (‚Pombalino‘ buildings)“, WHE report #92  M. Bostenaru Dan: „Prefabricated metal construction of the Modern Movement“, WHE report #95  B.H. Hashemi and M.G. Ashtiany: „Semi-rigid steel frame with ‚Khorjinee‘ connections“, WHE report #26  M. Bostenaru Dan: „Early reinforced concrete frame condominium building with masonry infill walls designed for gravity loads only“, WHE report #96 WHE = World Housing Encyclopedia http://www.world-housing.net/
  25. 25. Thank You for your attention!

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