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Torsion in buildings the Mexican research experience after the 1985 earthquake Gustavo Ayala

Torsion in buildings the Mexican research experience after the 1985 earthquake Gustavo Ayala. TORSI O N. Caus e s No coincidence of acting and resisting forces in structures with asymmetric plan distibutions of masses, stiffnesses and/or strengths. Kinematic e f f ects

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Torsion in buildings the Mexican research experience after the 1985 earthquake Gustavo Ayala

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  1. Torsion in buildings the Mexican research experience after the 1985 earthquake Gustavo Ayala

  2. TORSION Causes No coincidence of acting and resisting forces in structures with asymmetric plan distibutions of masses, stiffnesses and/or strengths. Kinematic effects Coupling between lateral and rotational displacements of the levels. Consequences Non-contemplated damage in asymmetric structures subjected intense earthquakes.

  3. DAMAGE STATISTICS 19th SEPTEMBER 1985, MEXICO EARTHQUAKE

  4. Torsion Design DESIGN RECOMMENDATIONS FOR TORSION Elastic models of single storey shear buildings. DESIGN PHYLOSOPHY It is formally accepted that under intense seismic events structural damage (non-linear behaviour) may occur.

  5. SPATIAL VARIATION OF THE TORSION CENTRE IN MULTI-STOREY BUILDINGS WITH IN-PLAN AND ELEVATION ASYMMETRY ( SHEAR AND BENDING MODELS)

  6. CENTRE OF TORSION “ The Centre of Torsion of a buuilding is defined as the loci on its levels or inter-storeys at which the seismic force or shear must be applied to produce only translations with no rotations “ PARAMETERS WHICH DEFINE THE LOCATION OF THE CENTRE OF TORSION. • Stiffness • Location of the elements • Distribution of lateral loads “ The CENTRE OF TORSION is not an INVARIANT“

  7. LOCATION OF THE CENTRE OF TORSION SHEAR MODELS • EXACT . • Infinite stiffnesses of beams • Plane frames • TRADITIONAL. • Bending on beams • Inter-storey stiffnesses of plane frames THREE DIMENSIONAL MATRIX FORMULATION

  8. BUILDING MODELS 4 levels

  9. BUILDING MODELS 15 levels

  10. BUILDING MODELS 4 levels

  11. BUILDING MODELS 15 levels

  12. Location of the torsion centre 4 levels Model I Model II

  13. Location of the torsion centre 4 levels Model III Model IV

  14. Location of the torsion centre 4 levels 15 levels Model V Model I

  15. Location of the torsion centre 15 levels Model II Model III

  16. Location of the torsion centre 15 levels Model IV Model V

  17. Location of the torsion centre 15 levels Model VI Model VII

  18. Location of the torsion centre 15 levels Model VIII

  19. INELASTIC TORSION

  20. BACKGROUND Parametric studies based on single storey models • Distribución en planta de las rigideces y resistencias. • Excentricidad estática • Relación de aspecto de la planta • Cociente Rr/ Rn • Periodo fundamental de vibrar ( T ) • Relación de frecuencias desacopladas ( W ) • Evaluación del criterio de diseño por Torsión del RCDF

  21. BACKGROUND 1 ) Gómez, Ayala and Jaramillo, 1987 2) Barrón, Ayala and Zapata, 1991

  22. BACKGROUND 3) García and Ayala, 1991 4) Zapata and Ayala,1993

  23. SOME RESULTS OBTAINED FROMSINGLE STOREY MODELS Relationships of Maximum Ductility Ratios vs. Strength Distribution in shear models with resisting elements in two orthogonal directions.

  24. SOME RESULTS OBTAINED FROMSINGLE STOREY MODELS Relationships of Maximum Ductility Ratios vs. Strength Distribution

  25. STUDY OF THE RESPONSE OF 3D BUILDING MODELSTORSIONALLY COUPLED

  26. INVESTIGATED MODEL

  27. CONSIDERED PARAMETERS • MASS AND STIFFNESS ASYMMETRIC. • DYNAMICA AMPLIFICATION FACTOR. FAdin = Mt Me Design Eccentricity : ed1= a es + b b ed2 = d es - b b

  28. TYPES AND LEVELS OF STRUCTURAL ASYMMETRY MASS ASYMMETRIC MODELS STIFFNESS ASYMMETRIC MODELS mean values

  29. INSTANTANEOUS CENTREOF SEISMIC SHEAR (CICS) Symmetric Model Model I Mass Asymmetric Interstorey 01

  30. INSTANTANEOUS CENTREOF SEISMIC SHEAR (CICS) SymmetricModel Model I Mass Asymmetric Interstorey 01

  31. INSTANTANEOUS CENTREOF SEISMIC SHEAR (CICS) Model III Mass Asymmetric Model II Mass Asymmetric Interstorey 01

  32. INSTANTANEOUS CENTREOF SEISMIC SHEAR (CICS) Interstorey 01 Modelo I Asimétrico en Rigidez Modelo II Asimétrico en Rigidez

  33. INSTANTANEOUS CENTREOF SEISMIC SHEAR (CICS) Model III Stiffness Asymmetric Interstorey 01

  34. INSTANTANEOUS CENTRE OF STIFFNESS (CIR) SYMMETRIC MODEL Interstorey 01

  35. INSTANTANEOUS CENTRE OF STIFFNESS (CIR) MODEL I MASS ASYMMETRIC Interstorey 01

  36. INSTANTANEOUS CENTRE OF STIFFNESS (CIR) MODEL II MASS ASYMMETRIC Interstorey 01

  37. INSTANTANEOUS CENTRE OF STIFFNESS (CIR) MODEL III MASS ASYMMETRIC Interstorey 01

  38. INSTANTANEOUS CENTRE OF STIFFNESS (CIR) MODEL I STIFFNESS ASYMMETRIC Interstorey 01

  39. INSTANTANEOUS CENTRE OF STIFFNESS (CIR) MODEL II STIFFNESS ASYMMETRIC Interstorey 01

  40. INSTANTANEOUS CENTRE OF STIFFNESS (CIR) MODEL III STIFFNESS ASYMMETRIC Interstorey 01

  41. SHEAR - TORSIONAL MOMENT HISTORY SUPERPOSED ON THE SUCT SYMMETRIC MODEL Interstorey 01

  42. SHEAR - TORSIONAL MOMENT HISTORY SUPERPOSED ON THE SUCT MODEL I MASS ASYMMETRIC Interstorey 01

  43. SHEAR - TORSIONAL MOMENT HISTORY SUPERPOSED ON THE SUCT MODEL II MASS ASYMMETRIC Interstorey 01

  44. SHEAR - TORSIONAL MOMENT HISTORY SUPERPOSED ON THE SUCT MODEL III MASS ASYMMETRIC Interstorey 01

  45. SHEAR - TORSIONAL MOMENT HISTORY SUPERPOSED ON THE SUCT MODEL I STIFFNESS ASYMMETRIC Interstorey 01

  46. SHEAR - TORSIONAL MOMENT HISTORY SUPERPOSED ON THE SUCT MODEL IISTIFFNESS ASYMMETRIC Interstorey 01

  47. SHEAR - TORSIONAL MOMENT HISTORY SUPERPOSED ON THE SUCT MODEL IIISTIFFNESS ASYMMETRIC Interstorey 01

  48. DYNAMIC AMPLIFICATION FACTOR

  49. EEFECT OF FUNDAMENTAL PERIOD

  50. STRUCTURAL MODELS Group 1 (Models 4 levels) Group 2 (Models 8 levels) Group 3 (Models 15 levels)

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