1. 29.05 –
Comparison Between Three Base Isolation Systems-Shake Table Test Studies
ID 516
DEPARTMENT FOR BUILDING STRUCTURES AND MATERIALS, DESIGN, ANALYSIS AND TESTING
Tashkov L., Krstevska L.,
University Ss. Cyril and Methodius in Skopje
Institute of Earthquake Engineering and Engineering Seismology (UKIM-IZIIS) - Skopje

2. Comparison Between Three Base Isolation Systems
-Shake Table Test Studies
Abstract:
This paper deals with three base isolation techniques for seismic protection of two different types of structures: liquid storage tanks and buildings. The effectiveness of these techniques was investigated experimentally on reduced scale models in laboratory conditions at the Dynamic Testing Laboratory of the Institute of Earthquake Engineering and Engineering Seismology, Skopje. The first technique was related to base isolation by standard rubber bearings. Such type of isolation was applied on the model of St. Nikita church built to the scale of 1/2.75. The second technique was related to base isolation by high strength rubber bearings. This type of bearings was applied on a liquid storage tank model built to the scale of 1/3. The third technique was related to base isolation by ALSC floating-sliding system. This technique was applied on a liquid storage tank model as well as on the St. Nicholas church model built to the scale of 1/3. First, a comparison was made between the church models (standard rubber and ALSC base-isolation system) and then between the reservoir models (high strength rubber and ALSC base-isolation system)
The comparative diagrams of the model responses showed superior behavior of the ALSC floating-sliding system in both cases.
DEPARTMENT FOR BUILDING STRUCTURES AND MATERIALS, DESIGN, ANALYSIS AND TESTING
Tashkov L., Krstevska L.
University Ss. Cyril and Methodius in Skopje
Institute of Earthquake Engineering and Engineering Seismology (UKIM-IZIIS) - Skopje

3. Comparison Between Three Base Isolation Systems
-Shake Table Test Studies
Case study No. 1: SHAKE-TABLE TEST OF 1/2.75 SCALED MODEL of st. nikita church BASE-ISOLATED BY laminated rubber bearings
St. Nikita church near Skopje considered as a prototype structure
Model of the St. Nikita church in scale 1/ 2.75 with laminated rubber bearings on the shake table at IZIIS
DEPARTMENT FOR BUILDING STRUCTURES AND MATERIALS, DESIGN, ANALYSIS AND TESTING
Tashkov L., Krstevska L.
University Ss. Cyril and Methodius in Skopje
Institute of Earthquake Engineering and Engineering Seismology (UKIM-IZIIS) - Skopje

4. Comparison Between Three Base Isolation Systems
-Shake Table Test Studies
Test results : St. Nikita church model
Figure Response of the St. Nikita church model Figure Response of the St. Nikita church model
base-isolated by rubber bearings fixed to the base
DEPARTMENT FOR BUILDING STRUCTURES AND MATERIALS, DESIGN, ANALYSIS AND TESTING
Tashkov L., Krstevska L.
University Ss. Cyril and Methodius in Skopje
Institute of Earthquake Engineering and Engineering Seismology (UKIM-IZIIS) - Skopje

5. Comparison Between Three Base Isolation Systems
-Shake Table Test Studies
Model of the St. Nikita church in scale 1/ 2.75 with laminated rubber bearings
DEPARTMENT FOR BUILDING STRUCTURES AND MATERIALS, DESIGN, ANALYSIS AND TESTING
Tashkov L., Krstevska L.
University Ss. Cyril and Methodius in Skopje
Institute of Earthquake Engineering and Engineering Seismology (UKIM-IZIIS) - Skopje

6. Comparison Between Three Base Isolation Systems
-Shake Table Test Studies
CASE STUDY NO 2: SHAKE-TABLE TEST OF 1/3.5 SCALED MODEL OF SENT NICHOLAS CHURCH, BASE ISOLATED BY FLOATING-SLIDING SYSTEM “ALSC”
St. Nicholas church near Psacha considered as a prototype structure
Model of St. Nicholas church in scale 1/3.5, base-isolated by ALSC floating-sliding system
DEPARTMENT FOR BUILDING STRUCTURES AND MATERIALS, DESIGN, ANALYSIS AND TESTING
Tashkov L., Shendova V., Krstevska L., Gavrilovic P.
University Ss. Cyril and Methodius in Skopje
Institute of Earthquake Engineering and Engineering Seismology (UKIM-IZIIS) - Skopje

7. Comparison Between Three Base Isolation Systems
-Shake Table Test Studies
The concept of ALSC floating-sliding base isolation system
Fr=N (1)
a) Ordinary sliding: N=G, L= (2)
b) ALSC sliding: N= G-L, GL  N
N  0 L=pS ; (3)
(for L=G ; N becomes 0 and Fr=0 i.e. floating state)
Fr = friction force;
 = friction coefficient at the contact surface;
N = active compressive force;
L = uplifting force produced by the liquid;
G = weight of the principal structure;
p=liquid pressure;
S= contact surface between the sliding and the fixed plate
DEPARTMENT FOR BUILDING STRUCTURES AND MATERIALS, DESIGN, ANALYSIS AND TESTING
Tashkov L., Krstevska L.
University Ss. Cyril and Methodius in Skopje
Institute of Earthquake Engineering and Engineering Seismology (UKIM-IZIIS) - Skopje

8. Comparison Between Three Base Isolation Systems
-Shake Table Test Studies
Test results : St. Nicholas church model
Figure Response of the St. Nicholas church model Figure Response of the St. Nicholas base isolated by floating-sliding system ALSC church model fixed to the base.
DEPARTMENT FOR BUILDING STRUCTURES AND MATERIALS, DESIGN, ANALYSIS AND TESTING
Tashkov L., Shendova V., Krstevska L., Gavrilovic P.
University Ss. Cyril and Methodius in Skopje
Institute of Earthquake Engineering and Engineering Seismology (UKIM-IZIIS) - Skopje

9. Comparison Between Three Base Isolation Systems
-Shake Table Test Studies
Fixed base model of Byzantine Church system
Montenegro-Petrovac
Input: 0.5g
DEPARTMENT FOR BUILDING STRUCTURES AND MATERIALS, DESIGN, ANALYSIS AND TESTING
Tashkov L., Krstevska L.
University Ss. Cyril and Methodius in Skopje
Institute of Earthquake Engineering and Engineering Seismology (UKIM-IZIIS) - Skopje

10. Comparison Between Three Base Isolation Systems
-Shake Table Test Studies
Base-isolated model of Byzantine Church by ALSC floating-sliding system
Harmonic 5Hz
input:0.8g
DEPARTMENT FOR BUILDING STRUCTURES AND MATERIALS, DESIGN, ANALYSIS AND TESTING
Tashkov L., Krstevska L.
University Ss. Cyril and Methodius in Skopje
Institute of Earthquake Engineering and Engineering Seismology (UKIM-IZIIS) - Skopje

11. Comparison Between Three Base Isolation Systems
-Shake Table Test Studies
CASE STUDY NO 3 – BASE-ISOLATED RESERVOIR WITH
ALSC FLOATING-SLIDING SYSTEM
DEPARTMENT FOR BUILDING STRUCTURES AND MATERIALS, DESIGN, ANALYSIS AND TESTING
Tashkov L., Krstevska L.
University Ss. Cyril and Methodius in Skopje
Institute of Earthquake Engineering and Engineering Seismology (UKIM-IZIIS) - Skopje

12. Comparison Between Three Base Isolation Systems
-Shake Table Test Studies
Figure 4.3. Response of reservoir isolated by ALSC Figure 4.4. Comparative presentation of reservoir system under harmonic excitation isolated by ALSC system and fixed to the base
DEPARTMENT FOR BUILDING STRUCTURES AND MATERIALS, DESIGN, ANALYSIS AND TESTING
Tashkov L., Krstevska L.
University Ss. Cyril and Methodius in Skopje
Institute of Earthquake Engineering and Engineering Seismology (UKIM-IZIIS) - Skopje

13. Comparison Between Three Base Isolation Systems
-Shake Table Test Studies
Base-isolated reservoir by ALSC floating-sliding system
Harmonic: 3.5Hz
Input: 1.2g
DEPARTMENT FOR BUILDING STRUCTURES AND MATERIALS, DESIGN, ANALYSIS AND TESTING
Tashkov L., Krstevska L.
University Ss. Cyril and Methodius in Skopje
Institute of Earthquake Engineering and Engineering Seismology (UKIM-IZIIS) - Skopje

14. Comparison Between Three Base Isolation Systems
-Shake Table Test Studies
Fixed base reservoir without base-isolation
Harmonic-3 Hz
Input: 0.7g
DEPARTMENT FOR BUILDING STRUCTURES AND MATERIALS, DESIGN, ANALYSIS AND TESTING
Tashkov L., Krstevska L.
University Ss. Cyril and Methodius in Skopje
Institute of Earthquake Engineering and Engineering Seismology (UKIM-IZIIS) - Skopje

15. Comparison Between Three Base Isolation Systems
-Shake Table Test Studies
CASE STUDY NO 4 – BASE-ISOLATED RESERVOIR WITH HIGH STRENGTH RUBBER BEARINGS
Fig.5.1. Model of a reservoir base-isolated with high strength rubber bearings.
DEPARTMENT FOR BUILDING STRUCTURES AND MATERIALS, DESIGN, ANALYSIS AND TESTING
Tashkov L., Krstevska L.
University Ss. Cyril and Methodius in Skopje
Institute of Earthquake Engineering and Engineering Seismology (UKIM-IZIIS) - Skopje

16. Comparison Between Three Base Isolation Systems
-Shake Table Test Studies
Fig.5.4. Comparative presentation of acceleration response of reservoir tsolted with soft and hard rubber- Harmonic excitation test (left) and Earthquake excitation test (right)
DEPARTMENT FOR BUILDING STRUCTURES AND MATERIALS, DESIGN, ANALYSIS AND TESTING
Tashkov L., Krstevska L.
University Ss. Cyril and Methodius in Skopje
Institute of Earthquake Engineering and Engineering Seismology (UKIM-IZIIS) - Skopje

17. Comparison Between Three Base Isolation Systems
-Shake Table Test Studies
Model of a reservoir base-isolated with high strength rubber bearings
DEPARTMENT FOR BUILDING STRUCTURES AND MATERIALS, DESIGN, ANALYSIS AND TESTING
Tashkov L., Krstevska L.
University Ss. Cyril and Methodius in Skopje
Institute of Earthquake Engineering and Engineering Seismology (UKIM-IZIIS) - Skopje

18. Comparison Between Three Base Isolation Systems
-Shake Table Test Studies
Model of a reservoir base-isolated with high strength rubber bearings
DEPARTMENT FOR BUILDING STRUCTURES AND MATERIALS, DESIGN, ANALYSIS AND TESTING
Tashkov L., Krstevska L.
University Ss. Cyril and Methodius in Skopje
Institute of Earthquake Engineering and Engineering Seismology (UKIM-IZIIS) - Skopje

19. Comparison Between Three Base Isolation Systems
-Shake Table Test Studies
COMPARISON BETWEEN TWO BASE ISOLATION SYSTEMS:
ALSC AND RUBBER BEARINGS IN CASE OF CHURCH MODELS
Figure 7.1. Response of the St. Nikita church mode Figure 7.2. Response of the St. Nicholas church
base-isolated with rubber bearings base-isolated with floating-sliding system ALSC.
DEPARTMENT FOR BUILDING STRUCTURES AND MATERIALS, DESIGN, ANALYSIS AND TESTING
Tashkov L., Krstevska L.
University Ss. Cyril and Methodius in Skopje
Institute of Earthquake Engineering and Engineering Seismology (UKIM-IZIIS) - Skopje

20. Comparison Between Three Base Isolation Systems
-Shake Table Test Studies
Comparison between two base isolation systems: ALSC and Rubber bearings in case of reservoirs
base isol- hatedard rubber
base isolated- ALSC
Input
Input
base isolated - soft rubber
base isolated- ALSC
. Comparison between hard rubber, soft rubber and ALSC base-isolation system
DEPARTMENT FOR BUILDING STRUCTURES AND MATERIALS, DESIGN, ANALYSIS AND TESTING
Tashkov L., Krstevska L.
University Ss. Cyril and Methodius in Skopje
Institute of Earthquake Engineering and Engineering Seismology (UKIM-IZIIS) - Skopje

21. Comparison Between Three Base Isolation Systems
-Shake Table Test Studies
5. CONCLUSIONS
The presented techniques of base isolation showed different effectiveness in reduction of seismic energy transmission from the foundation to the structure in all 4 case studies. Based on the performed experimental investigations, the following conclusions can be drawn:
The base isolation with laminated rubber isolators applied to the model of the St. Nikita church shows that it can effectively protect the historical monuments from severe damage up to limited level of input acceleration (0.5g for the model);
The ALSC floating-sliding base isolation system applied to the model of the St. Nicholas Church shows very effective reduction of the response during dynamic excitation. The effectiveness of this isolation system is much better than that of the laminated rubber isolators, preventing damage to the model up to 1.5 g ( the limit capacity of the IZIIS’ shake table);
The base isolation with high strength rubber isolators applied to the reservoir model shows that base isolators with hard rubber do not have any isolation effect, while soft rubber has limited effectiveness (for the frequency of excitation higher than 3.0 Hz.) In the lower frequency range, it produces amplification of the input motion. It can be concluded that this base-isolation is very sensitive to design conditions;
The base isolation with ALSC system applied to the model of reservoir shows very effective reduction of the response during dynamic excitation. The effectiveness of this isolation system is much better than that of the high strength rubber system, preventing damage to the model and providing almost constant and effective base-isolation within the broad frequency and amplitude range of excitation(frequency range 0-25 Hz, amplitude response less than 0.25g for input up to 1.5g) .
DEPARTMENT FOR BUILDING STRUCTURES AND MATERIALS, DESIGN, ANALYSIS AND TESTING
Tashkov L., Krstevska L.
University Ss. Cyril and Methodius in Skopje
Institute of Earthquake Engineering and Engineering Seismology (UKIM-IZIIS) - Skopje

22. Thank you