structure control system

1. STRUCTURE CONTROL
SYSTEM
Prepared by:-
-Naman Kantesaria(120280106039)
-Jay Patel(120280106037)
-Vipul Chavda(120280106063)

2. INTRODUCTION
 Civil engineering structures located in environments where
earthquakes or large wind forces are common will be
subjected to serious vibrations during their lifetime. These
vibrations can range from harmless to severe with the later
resulting in serious structural damage and potential structural
failure.

3. SEISMIC PROTECTION OF STRUCTURES
 The Traditional Technique of a seismic
Design
( increase the stiffness of structures by enlarging the section
of columns, beams, shear walls, or other elements)
Modern Approach through
Structural Controls
(by installing some devices, mechanisms, substructures in the
structure to change or adjust the dynamic performance of the
structure)

4. BASIC PRINCIPLES OF SEISMIC
RESPONSE CONTROL
 Control systems add damping to the structure and/or alter the
structure’s dynamic properties. Adding damping increases the
structural energy-dissipating capacity, and altering structural
stiffness can avoid resonance to external excitation, thus
reducing structural seismic response.

5. STRUCTURE CONTROL SYSTEMS
1.Passive control systems
2.Active Control systems
3.Semi-active control systems
4.Hybrid control systems

6. PASSIVE CONTROL SYSTEMS
 The passive control system does not require an external
power source and being utilizes the structural motion to
dissipate seismic energy or isolates the vibrations so
that response of structure can be controlled

7. THE PASSIVE CONTROL DEVICES INCLUDES
1. Base Isolation
2. Passive Energy Dissipating
(PED) Devices

8. BASE ISOLATION
 A building mounted on a material with low lateral stiffness,
such as rubber, achieves a flexible base.
 During the earthquake, the flexible base is able to filter out
high frequencies from the ground motion and to prevent the
building from being damaged or collapsing
- deflecting the seismic energy and
- absorbing the seismic energy

9. BEHAVIOR OF BUILDING STRUCTURE
WITH BASE ISOLATION SYSTEM
Conventional Structure Base-Isolated Structure

10. VARIOUS TYPE OF BASE ISOLATION
Elastomeric Bearings:
-Low-Damping Natural or Synthetic Rubber Bearing
- High-Damping Natural Rubber Bearing
- Lead-Rubber Bearing
(Low damping natural rubber with lead core)
Sliding Bearings
- Flat Sliding Bearing
- Spherical Sliding Bearing

11. ELASTOMERIC BEARINGS
Major Components:
- Rubber Layers: Provide
lateral flexibility
- Steel Shims: Provide
vertical stiffness to
support building weight
while limiting lateral
bulging of rubber
- Lead plug: Provides source
of energy dissipation

12. LOW DAMPING NATURAL OR SYNTHETIC
RUBBER BEARINGS
 Linear behavior in shear for shear
strains up to and exceeding 100%.
 Damping ratio = 2 to 3%
 Advantages:
- Simple to manufacture
- Easy to model
- Response not strongly sensitive to
rate of loading, history of loading,
temperature, and aging.
 Disadvantage:
-Need supplemental damping system

13. HIGH-DAMPING NATURAL RUBBER
BEARINGS
• Damping increased by adding extra-fine carbon black, oils or resins,
and other proprietary fillers
• Maximum shear strain = 200 to 350%
• Damping ratio = 10 to 20% at shear strains of 100%
• Effective Stiffness and Damping depend on:
- Elastomer and fillers
- Contact pressure
- Velocity of loading
- Load history (scragging)
- Temperature

14. LEAD-RUBBER BEARINGS
 damping properties can be improve by
plugging a lead core into the bearing
 damping of the lead-plug bearing
varies from 15% to 35%.
 The Performance depends on the
imposed lateral force
 The hysteretic damping is developed
with energy absorbed by the lead
core.
 Maximum shear strain = 125 to 200%

16. SLIDING BEARINGS
 The imposed lateral force is resisted
by the product of the friction
coefficient and the vertical load
applied on the bearing

19. PASSIVE ENERGY DISSIPATING DEVICES
(PED)
 Mechanical devices to dissipate or absorb a portion of
structural input energy, thus reducing structural response and
possible structural damage.
• Metallic Yield Dampers
• Friction Dampers
• Visco-elastic Dampers
• Viscous Fluid Dampers, And
• Tuned Mass Dampers And Tuned Liquid Dampers.

20. METALLIC YIELD DAMPERS
 Metallic yield damper:
relies on the principle that
the metallic device
deforms plastically, thus
dissipating vibratory
energy

23. FRICTION DAMPERS
 here friction
between sliding faces
is used to dissipate
energy

25. VISCO-ELASTIC DAMPERS
 Visco-elastic (VE)
dampers utilize high
damping from VE
materials to dissipate
energy through shear
deformation.
Such materials include
rubber, polymers, and
glassy substances.

27. VISCOUS FLUID DAMPERS
 A viscous fluid damper
consists of a hollow
cylinder filled with a
fluid. As the damper
piston rod and piston
head are stroked, The
fluid flows at high
velocities , resulting in
the development of
friction

30. TUNED MASS DAMPERS AND TUNED
LIQUID DAMPERS
A mass that is connected to a
structure by a spring and a
damping element without any
other support,in order to
reduce vibration of the
structure
Tuned liquid dampers are similar
to tuned mass dampers except
that the mass-spring-damper
system is replaced by the
container filled with fluid

31. Tuned mass dampers
Tuned Mass dampers

32. ACTIVE CONTROL SYSTEMS
In the active control, an external source of energy is used to
activate the control system by providing an analog signal to it.
This signal is generated by the computer following a control
algorithm that uses measured responses of the structure

33. TYPES OF ACTIVE CONTROL SYSTEMS
 Active Mass Damper Systems
 Active Tendon Systems
 Active Brace Systems

34. ACTIVE MASS DAMPER SYSTEMS
 It evolved from TMDs
with the introduction of
an active control
mechanism.

35. ACTIVE TENDON SYSTEMS
 Active tendon control
systems consist of a
set of pre-stressed
tendons whose
tension is controlled
by electro-hydraulic
servomechanisms

36. SEMI-ACTIVE CONTROL SYSTEMS
 It compromise between the passive and active control
devices.
 the structural motion is utilized to develop the control
actions or forces through the adjustment of its
mechanical properties
 The action of control forces can maintained by using
small external power supply or even with battery

37. SEMI-ACTIVE DEVICES
1.Stiffness control devices
2.Electro-rheological dampers
3.Magnetorhelogical dampers
4.Friction control devices
5.Fluid viscous dampers
6.Tuned mass dampers
7.Tuned liquid dampers

38. ELECTRO-RHEOLOGICAL DAMPERS
 ER fluids that contain
dielectric particles suspended
within non-conducting
viscous fluids
 When the ER fluid is subjected
to an electric field, the
dielectric particles polarize
and become aligned, thus
offering resistance to the flow.

39. STIFFNESS CONTROL DEVICES
Modify:
- the stiffness
-the natural vibration
characteristics
So create a non-
resonant condition
during earthquake

40. MAGNETO-RHEOLOGICAL DAMPERS
 MR fluid contains micron-size,
magnetically polarizable particles
dispersed in a viscous fluid
 When the MR fluid is exposed to
a magnetic field, the particles in
the fluid polarize, and the fluid
exhibits visco-plastic behavior,
thus offering resistance to the
fluid flow.

41. HYBRID CONTROL SYSTEMS
 Combine controls system together
 Passive + Active
 Passive + Semi-Active
 Smart base-isolation
 Reduce external power requirement
 Improve reliability
 When loss of electric during earthquake, hybrid control can act as a
passive control
 Reduce construction and maintenance costs due to active or
semi-active