• Share
  • Email
  • Embed
  • Like
  • Save
  • Private Content
Modelling and analysis of base isolated structures
 

Modelling and analysis of base isolated structures

on

  • 195 views

Modelling and analysis of base isolated structures with the aid of IperSpace Max

Modelling and analysis of base isolated structures with the aid of IperSpace Max

Statistics

Views

Total Views
195
Views on SlideShare
194
Embed Views
1

Actions

Likes
0
Downloads
15
Comments
0

1 Embed 1

http://darya-ld1.linkedin.biz 1

Accessibility

Categories

Upload Details

Uploaded via as Adobe PDF

Usage Rights

© All Rights Reserved

Report content

Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
  • Full Name Full Name Comment goes here.
    Are you sure you want to
    Your message goes here
    Processing…
Post Comment
Edit your comment

    Modelling and analysis of base isolated structures Modelling and analysis of base isolated structures Presentation Transcript

    • MODELLING AND ANALYSIS OF BASE ISOLATED STRUCTURES THROUGH IPERSPACE MAX Copyright  Soft.Lab srl D.M. 14/01/2008 (Italian Technical Construction Regulation) Phd Ing. Stefano Ciaramella Technical Consultant R&D 1 For more informations you can call: ing. Francesco Ambrosio Sales Director salesdirector@soft.lab.it Tel: +39 – 3318559813
    • 2 The Software… Copyright  Soft.Lab srl http://www.soft.lab.it – salesdirector@soft.lab.it
    • 3 The Software… Copyright  Soft.Lab srl http://www.soft.lab.it - salesdirector@soft.lab.it
    • 4 The Software… Copyright  Soft.Lab srl http://www.soft.lab.it - salesdirector@soft.lab.it
    • 5 The Software… Copyright  Soft.Lab srl http://www.soft.lab.it - salesdirector@soft.lab.it
    • 6 The Software… Copyright  Soft.Lab srl http://www.soft.lab.it - salesdirector@soft.lab.it
    • 7 The Software… Copyright  Soft.Lab srl http://www.soft.lab.it - salesdirector@soft.lab.it
    • 8 Seismic isolation The approach to the earthquake-resistant construction problem: CAPACITY  DEMAND where:  the demand depends on the seismic event, which generates inertial forces in the structure. These forces are equal to the product of the masses of the structure and the accelerations due to the vibration induced by the event itself.  the capacity depends on the strength and on the non-linear deformability of the structure. Seismic Isolation: is an alternative design approach that acts on demand drastically limiting the accelerations Copyright  Soft.Lab srl http://www.soft.lab.it - salesdirector@soft.lab.it
    • a) increase of the fundamental period of the building to bring it in the field of lower responses to accelerations b) limitation of the maximum horizontal force transmitted 9 a) Increase of the period (and dissipation) b) Limitation of the force (and dissipation) Seismic isolation strategy Copyright  Soft.Lab srl http://www.soft.lab.it - salesdirector@soft.lab.it Model of a base isolated building
    • 10 Superstructure Substructure Isolation Interface Seismic isolation system Copyright  Soft.Lab srl http://www.soft.lab.it - salesdirector@soft.lab.it
    • 11 Benefits of seismic isolation  Economically acceptable and convenient structures  Drastic reduction of the story drift which allow to create structures that do not suffer damage for devastating earthquakes  High protection of structural content  The people in the building have a minor perception of the seismic event  Great savings for repairs after high intensity earthquakes  If the building has strategic importance the earthquakes does not cause the interruption of the service. Copyright  Soft.Lab srl http://www.soft.lab.it - salesdirector@soft.lab.it
    • Definition of the characteristics of the isolating system:  Stiffness  Dissipative capacity Identification of the period-damping couple (Tis, esi). Compared to the configuration of fixed-based structure (FB), this approach determines a better balancing between a satisfactory reduction of the seismic effects and horizontal displacement of the superstructure. 12 System pre-dimensioning Case Configuration T  1 Structure (FB) 0.47 sec 5% 2 Structure (BI) 1.50 sec 10% 3 Structure (BI) 2.00 sec 10% 4 Structure (BI) 2.50 sec 10% 5 Structure (BI) 1.50 sec 15% 6 Structure (BI) 2.00 sec 15% 7 Structure (BI) 2.50 sec 15% 3/4 1 0.47secfbT C H   fixed-based structure (FB) base-isolated structure (BI) Copyright  Soft.Lab srl http://www.soft.lab.it - salesdirector@soft.lab.it
    • 13 System pre-dimensioning 2 iso is esi M T K  2 2 esi iso is K M T         ,iso e is esiF M S T      2 , , 2 iso e is esi is dc e is esi esi M S T T d S T K             Horizontal equivalent stiffness of the isolating system:  Equivalent period of the isolating system:  Resultant of horizontal forces applied to the isolated system:  Displacement of the stiffness centre of the isolating system: Copyright  Soft.Lab srl http://www.soft.lab.it - salesdirector@soft.lab.it
    • Palette Widget Property Widget 14 Copyright  Soft.Lab srl http://www.soft.lab.it - salesdirector@soft.lab.it
    • 15 Copyright  Soft.Lab srl http://www.soft.lab.it - salesdirector@soft.lab.it
    • 16 Copyright  Soft.Lab srl http://www.soft.lab.it - salesdirector@soft.lab.it
    • Response Spectrums 17 Period [sec] Copyright  Soft.Lab srl http://www.soft.lab.it - salesdirector@soft.lab.it
    • Acceleration Displacement Response Spectrum 18 Copyright  Soft.Lab srl http://www.soft.lab.it - salesdirector@soft.lab.it
    • 19 Case Configuration T [sec]  [%] ddc [mm] 2 Structure (BI) 1.50 10% 156 3 Structure (BI) 2.00 10% 218 4 Structure (BI) 2.50 10% 280 5 Structure (BI) 1.50 15% 135 6 Structure (BI) 2.00 15% 189 7 Structure (BI) 2.50 15% 242   2 , 2 dc e T d S T          Stiffness Centre Displacement Copyright  Soft.Lab srl http://www.soft.lab.it - salesdirector@soft.lab.it
    • 20 Copyright  Soft.Lab srl http://www.soft.lab.it - salesdirector@soft.lab.it
    • Response Spectrums 21 Elastic Spectrum Structure Project Spectrum Structure (FB) Period [sec] Copyright  Soft.Lab srl http://www.soft.lab.it - salesdirector@soft.lab.it
    • 22 Case Configuration T [sec]  [%] Shear Force [KN] 1 Structure (FB) 0.47 5% 1550 2 Structure (BI) 1.50 10% 1260 3 Structure (BI) 2.00 10% 960 4 Structure (BI) 2.50 10% 740 5 Structure (BI) 1.50 15% 1100 6 Structure (BI) 2.00 15% 770 7 Structure (BI) 2.50 15% 630  , 600 eF M S T M t    Shear force at the bottom of the superstructure Copyright  Soft.Lab srl http://www.soft.lab.it - salesdirector@soft.lab.it
    • Case Configuration T [sec] Kesi [KN/m] ki [KN/m] 2-5 Structure (BI) 1.50 13861 770.0 3-6 Structure (BI) 2.00 7896 438.7 4-7 Structure (BI) 2.50 5053 280.7 23 2 2 790 esi iso is iso K M T M t         Horizontal stiffness pillarsofnKk esii /  Copyright  Soft.Lab srl http://www.soft.lab.it - salesdirector@soft.lab.it
    • 24 Case Configuration T [sec]  [%] ddc [mm] Shear Force [KN] Kesi [KN/m] ki [KN/m] 1 Structure (FB) 0.47 5% - 1550 - - 2 Structure (BI) 1.50 10% 156 1260 13861 770.0 3 Structure (BI) 2.00 10% 218 960 7896 438.7 4 Structure (BI) 2.50 10% 280 740 5053 280.7 5 Structure (BI) 1.50 15% 135 1100 13861 770.0 6 Structure (BI) 2.00 15% 189 770 7896 438.7 7 Structure (BI) 2.50 15% 242 630 5053 280.7 Seismic Effects: 50% reduction compared to the FB configuration Summary of the results Copyright  Soft.Lab srl http://www.soft.lab.it - salesdirector@soft.lab.it
    • Palette Widget Property Widget 25 Copyright  Soft.Lab srl http://www.soft.lab.it - salesdirector@soft.lab.it
    • 26 d =189 mm + 30% =246 mm Ko = 0.439 kN/mm Preliminary Analysis Copyright  Soft.Lab srl http://www.soft.lab.it - salesdirector@soft.lab.it
    • 27 1. Go to the section Isolatori (“Isolator”) in the widget Elementi e click on Nuovo (“New”). 2. Insert the code for the new isolator. 3. In the property widget (“Proprietà”) through the section Generici, insert the vertical and horizontal stiffness taken from the catalogue. Adding an isolating element to the program library Copyright  Soft.Lab srl http://www.soft.lab.it - salesdirector@soft.lab.it
    • 28 Inserting isolators in the model of the structure 1. Selecting one or more pillars in the substructure. 2. Click on Crea (“Create”)  Isolatore sui selezionati (“selected isolators”) 3. Choose the isolator type, define its high and confirm (√) Copyright  Soft.Lab srl http://www.soft.lab.it - salesdirector@soft.lab.it
    • 29 Structural analysis: fixed-based structure 1st mode 2nd mode 3rd mode Copyright  Soft.Lab srl http://www.soft.lab.it - salesdirector@soft.lab.it
    • 30 Structural analysis: fixed-based structure Copyright  Soft.Lab srl http://www.soft.lab.it - salesdirector@soft.lab.it T = 0.47 secPreliminary Analysis
    • 31 Structural analysis: fixed-based structure Copyright  Soft.Lab srl http://www.soft.lab.it - salesdirector@soft.lab.it F = 155000 daNPreliminary Analysis
    • 32  Use of isolation devices “FIP INDUSTIALE” series SI-S 400/125  Reduction of the elastic spectrum for T  0,8 Tis = 1.6 sec  Assumes  = esi = 15% for T  0,8 Tis and  = 5% for T < 0,8 Tis Structural analysis: base-isolated structure Copyright  Soft.Lab srl http://www.soft.lab.it - salesdirector@soft.lab.it
    • 33 For the ultimate limit state verification, the needed resistance of structural elements of the superstructure can be met by considering the seismic effects reduced by the factor of 1/q=0.6667, where q=1.5 is the structure factor. Structural analysis: base-isolated structure Copyright  Soft.Lab srl http://www.soft.lab.it - salesdirector@soft.lab.it
    • 34 Structural analysis: base-isolated structure Copyright  Soft.Lab srl http://www.soft.lab.it - salesdirector@soft.lab.it T = 2.0 secPreliminary Analysis
    • 35 Structural analysis: base-isolated structure Copyright  Soft.Lab srl http://www.soft.lab.it - salesdirector@soft.lab.it F = 77000 daNPreliminary Analysis
    • 36 The following figure shows the deformation of the structure due to a seismic event aligned with the x-axis. The isolator maximum horizontal displacement is d = 221 mm, not far from our preliminary prediction (246 mm) and however under the limit of the isolator (250 mm). Copyright  Soft.Lab srl http://www.soft.lab.it - salesdirector@soft.lab.it
    • 37 Limit State Verification Copyright  Soft.Lab srl http://www.soft.lab.it - salesdirector@soft.lab.it  Ultimate Limit State Verification  Damage Limit State Verification
    • 38 Ultimate Limit State Verification Copyright  Soft.Lab srl http://www.soft.lab.it - salesdirector@soft.lab.it The superstructure and substructure should be designed with reference to construction details related to the non seismic zone (Geometric and Reinforcement Limitations)
    • 39 Ultimate Limit State Verification Copyright  Soft.Lab srl http://www.soft.lab.it - salesdirector@soft.lab.it
    • 40 Damage Limite State Verification For the superstructure, the verification must be carried out controlling that the story drift, obtained from the analysis, is under the 2/3 of the Damage Limite State limits of conventional structures. This verification is carried out by setting k(*h) = 0.005x2/3 = 0.00333333 into the “Impalcati” section of the property widget and finally checking the results. Copyright  Soft.Lab srl http://www.soft.lab.it - salesdirector@soft.lab.it
    •  However, it remains to be performed the verification for the parts involved in the non-dissipative function. These should remain in the elastic range even under the conditions of maximum stress, according to the rules relating to the materials they are made. For this verification, also a safety factor (≥1.5) have to be taken into account.  For the replacement of isolators, the lifting by hydraulic jacks could be required. Therefore it is necessary to evaluate the dimensions of the concrete squat above the isolation interface and calculate an additional bottom reinforcement.  In order to prevent or reduce traction in the seismic isolation devices, the vertical load design "V“, due to seismic actions, should be compressive or zero (V ≥ 0). In the case that V < 0, the modulus of the tensile stress should be minor both of 2G and 1 Mpa into the isolators (G is the shear modulus).  For further examinations regarding these issues, the reader can refer to the specific publications available. 41 Further Verifications Copyright  Soft.Lab srl http://www.soft.lab.it – salesdirector@soft.lab.it For more informations you can call: ing. Francesco Ambrosio Sales Director salesdirector@soft.lab.it Tel: +39 – 3318559813