2. BY Eng.\ Ayman Abdo Mohamed Hussein
Zagazig University
Faculty of Engineering
Structural Eng. Depart.
التحكــــم فى تصــــــادم المنشــــــآت المعزولة زلزاليــــــا
POUNDING CONTROL OF BASE ISOLATED STRUCTURES BY
Eng.\ Ayman Abdo Mohamed Hussein

3. Under Supervision of : Prof. Dr. Sayed Abd El-Salam Dr. Ass. Prof. Dr.
Zagazig University
Faculty of Engineering
Structural Eng. Depart.
Under Supervision of :
Prof. Dr.
Sayed Abd El-Salam
Professor of Structure Engineering
Faculty of Engineering Zagazig University
Dr.
H. E. Abd-El-Mottaleb
Department of Structural Engineering
Zagazig University
Ass. Prof. Dr.
Atef Eraky Bakry
Department of Structural Engineering
Zagazig University

4. OUTLINES Introduction Modeling
Effect of pounding on adjacent structures
Control of Base Isolated Buildings Pounding
Conclusions and future work

5. INTRODUCTION  base isolation and pounding phenomenon Base-isolated
The base isolation technique used for protect the strategically important structures.
The basic goal of the base isolation is to increases the lateral flexibility and also increases the effective damping through the energy dissipated
 But It must be more flexible, but it must still be stiff enough to resist pounding.
Base-isolated
Fixed base

6. INTRODUCTION  Pounding occurs between the adjacent structures:
The 1985 Mexico City Earthquake Pounding

7. Objectives
1- Establish a reliable analytical model to simulate building pounding.
2- Assess the effect of gap width in pounding response.
3- Assess the effect of real earthquake ground motions is studied to find the pounding response.
4- Study the pounding for buildings with different characteristics.
5- Assess the benefit of using supplemental viscous damping devices to reduce impact forces, and story drift in the buildings subjected to pounding.

8. OUTLINES Introduction Modeling
Effect of pounding on adjacent structures
Control of pounding in isolated structures
Conclusions and future work

9. Base Isolated Structures
Modeling
Previous Works
Pounding in
Fixed Base Structures
Pounding in
Base Isolated Structures
Vasant and R. S. jangid - Kun YE et al. - Robert J. - Shehata E.-Muthukumar - Chris et al. -Abdullah et al.
Vasant and R. S. jangid -Kun et al. - Panayiotis et al. - Anagnostopoulos S.
Pounding
Control
Vasant mastagar and R. S. jangid - Nawawi, et al. - Orlando, et al. - Zhong, L. - Klein et al. - Yang and Xu

10. Modeling Fixed Base Structures Equation of Motion
For the two Buildings

11. Modeling m1v1 + m2v2 m1u1 + m2u2 IMPACT Partially elastic collision
Most collisions fall between elastic and
perfectly inelastic collisions (e= )
For concrete collision e= (e=.65)
m1u1 + m2u2
Before collision
m1v1 + m2v2
After collision
When Fext = 0, =

12. Modeling
Classical Theory of Impact:

13. Modeling
Base Isolated
Structures
** Bilinear model
Equation of Motion

14. Modeling
Base Isolated
Structures

15. Modeling
Equations of the Total Energy

16. Modeling
Using viscous dampers in the reduction of pounding force at the Points of Collision

17. Modeling
Equation of motion assuming connected damper

18. OUTLINES Introduction Modeling
Effect of pounding on adjacent structures
Control of pounding in isolated structures
Conclusions and future work

19. FBP FB First Story Effect of pounding on adjacent structures
1- Fixed Base Buildings ( Harmonic Excitation wex= 4.0 rad) FB
FBP
First Story

20. FB FBP Second Story Effect of pounding on adjacent structures
Fixed Base Buildings ( Harmonic Excitation ) FB
FBP
Second Story

21. base BI BIP Effect of pounding on adjacent structures
2- Base Isolated Buildings ( Harmonic Excitation ) BI
BIP
base

22. BI BIP Second Story Effect of pounding on adjacent structures
Base Isolated Buildings ( Harmonic Excitation ) BI
BIP
Second Story

23. FBP BIP Effect of pounding on adjacent structures PARAMETRIC STUDY
1- mass ratio(mB/mA) MA MB
building A
MB=2.0 MA
building A
MB=0.5 MA MB
FBP
BIP
building B
building B
ωn = √K/ M
λ = MB/ MA

24. 2- plastic shear capacity Base of A
Effect of pounding on adjacent structures BI
BIP
2- plastic shear capacity F X
Base of A
First of A Qp
Second of A

25. 2- plastic shear capacity
Effect of pounding on adjacent structures
2- plastic shear capacity
building A at wex= 4.0 rad.
building A at wex= 1.6 rad.

26. 2- plastic shear capacity First of B
Effect of pounding on adjacent structures BI
BIP
base of B
2- plastic shear capacity
First of B
Second of B

27. BIP BI Base of A First of A Second of A
Effect of pounding on adjacent structures
3- post- pre stiffness ratio
BIP BI Kp F X Qp Kp Ke
α = Ke
Base of A
First of A
Second of A

28. BI BIP Base of B First of B Second of B
Effect of pounding on adjacent structures BI
BIP
Base of B
First of B
Second of B

29. Effect of pounding on adjacent structures
4-Effect of Separation Distance
No of impacts
Max rel disp. BIP of A
Max rel disp. FBP
Max rel disp. BIP of B

30. Effect of pounding on adjacent structures
Behavior of Buildings under Earthquake Excitations
Elcentro
Northridge
Elcentro
Spec. accel. (cm/sec2)
frequency
(d)
Northridge
Loma
Kobe
Loma
Kobe
Time history
Fourier spectrum

31. FB & FBP BI & BIP Effect of pounding on adjacent structures
Top disp. Of A
Top disp. Of A
Top disp. Of B
Top disp. Of B
Upper disp. against Northridge earthquake

32. FB & FBP BI & BIP Effect of pounding on adjacent structures
Base shear. against Northridge earthquake

33. FB FBP Effect of pounding on adjacent structures Effect of Mass Ratio
Upper story of building A
Upper story of building B

34. BIP BI Effect of pounding on adjacent structures Effect of Mass Ratio
Upper story of building A
Upper story of building B

35. FBP BIP Effect of pounding on adjacent structures
Effect of separation distance
FBP
BIP

36. BI BIP Effect of pounding on adjacent structures
Effect of plastic shear capacity BI
BIP
Upper story of building A
Upper story of building B

37. BI BIP Effect of pounding on adjacent structures
Effect of post-pre stiff ratio BI
BIP
Upper story of building A
Upper story of building B

38. OUTLINES Introduction Modeling
Effect of pounding on adjacent structures
Control of pounding in isolated structures
Conclusions and future work

39. Building A Building B Control of pounding in isolated structures base
first
second

40. Control of pounding in isolated structures
(ton)
The effect of frequency of the excitation and yield disp. on the total energy
the energy ratio (TEc /TE) at wex=2.0 rad.

41. Control of pounding in isolated structures

42. Control of pounding in isolated structures
Effect of damper stiffness & post stiffness

43. Control of pounding in isolated structures
Effect of yield disp. & post stiffness

44. Control of pounding in isolated structures
Effect of Structure Damping & Yield Disp.

45. Control of pounding in isolated structures
Effect of Natural Freq. & Damper Stiffness

46. Control of pounding in isolated structures
Damper Stiffness & Structure damping

47. Base First floor Second floor
Control of pounding in isolated structures
The optimum parameters of the damper
Base
Kd =20000 t/m,
α = 0.0,
Fy= 33.0 ton >>> wo=10
First floor
Second floor

48. OUTLINES Introduction Modeling
Effect of pounding on adjacent structures
Control of pounding in isolated structures
Conclusions and future work

49. Conclusions
1- Pounding increases the lighter floors response in adjacent base isolated buildings while decreases the heavier floors response.
2- Pounding increases the response of the floors of the adjacent fixed base buildings.
3- For the isolated buildings at the resonance region, the very small and very high isolator plastic shear capacity increases the bounded response, while away the resonance region, the decrease of plastic shear capacity decrease the response.

50. Conclusions
4- While small post-pre stiffness ratio decrease obviously the floors responses of the unbounded base isolated building.
5- When sufficient gap is allowed between the adjacent base isolated buildings, the effect of the pounding decreases.
6- The response of the base isolated bounded and unbounded depends on the power of the earthquake and frequency content.
7- When the use of viscous dampers, these damper have optimum yield force that minimize the energy.

51. Conclusions
8- The optimum yield force for the connected dampers increases for the stiff buildings rather than the flexible ones.
9- Connected dampers with small post-pre stiffness ratio are more efficient than that with large values for all cases of dampers.
10- After a specific value of connected dampers stiffness, the increase of the stiffness reduce slightly system response.

52. Future works
The present study could be complemented with additional research in the following areas:
Experimental shake-table testing of scaled buildings models to study the effects of pounding.
The developed program may be extended to investigate other cases of pounding such that which occurred in the buildings with different story levels.

53. Thank You

54. الحمد لله الذى هدانا لهذا وما
كنا لنهتدى لولا أن
هدانا الله