Download - Base isolation and dampers
-
8/17/2019 Base isolation and dampers
1/31
Base isolation and
dampers
1
-
8/17/2019 Base isolation and dampers
2/31
This is Haiti presidential Palace before the Earthquake
-
8/17/2019 Base isolation and dampers
3/31
And this is the same palace after disaster.
-
8/17/2019 Base isolation and dampers
4/31
Classification of Seismic Protection Systems
SEISMIC RESISTANT DESIGN OF
STRUCTURES
DUCTILITY / STRENGTH
BASED DESIGN METHODS
ACTIVE CONTROL
METHODS
PASSIVE CONTROL
METHODS
RESPONSE CONTROL BASED
DESIGN METHODS
HYBRID / SEMI ACTIVE
CONTROL METHODS
4
-
8/17/2019 Base isolation and dampers
5/31
Classification of Seismic Protection Systems
PASSIVE CONTROL METHODS
ISOLATION ENERGY DISSIPATION
BASE ISOLATION FLOOR ISOLATION ROOF ISOLATION
5
-
8/17/2019 Base isolation and dampers
6/31
Base Isolation
Introduction of Flexible Isolator Elements at the foundation level of
the structure so that the sub-structure (below ground level) and
super structure (above ground level) are isolated from each other
The flexible isolation system partially absorbs (through Damping
action) and partially reflects (through Filtering action) a major
portion of the earthquake energy and reduces the energy
dissipation demand of the super structure to a major extent
resulting in increased survivability
6
-
8/17/2019 Base isolation and dampers
7/31
Mechanism of Base Isolation
7
-
8/17/2019 Base isolation and dampers
8/31
Residential Building in Indonesia
Seismically Isolated Structures - Examples
-
8/17/2019 Base isolation and dampers
9/31
Residential Complex in China
Seismically Isolated Structures - Examples
-
8/17/2019 Base isolation and dampers
10/31
Hospital Building, Bhuj, India
The first base isolated structure is the new 300 bed Bhuj Hospital, reconstructed
after the devastating earthquake of 26 Jan 2001
Seismically Isolated Structures - Examples
-
8/17/2019 Base isolation and dampers
11/31
Types of Base Isolation Devices
Lead – Plug Rubber
Bearing
Friction – Pendulum SystemGERB-Spring System
1. Laminated Rubber Bearings (LRB) : Natural or Synthetic Rubber
2. Laminated Lead – Rubber Bearings
3. Sliding / Friction based isolation systems: Friction Pendulum
4. Spring type (GERB) isolation systems
Laminated Rubber
Bearing
11
-
8/17/2019 Base isolation and dampers
12/31
12
-
8/17/2019 Base isolation and dampers
13/31
13
-
8/17/2019 Base isolation and dampers
14/31
14
-
8/17/2019 Base isolation and dampers
15/31
15
-
8/17/2019 Base isolation and dampers
16/31
Suitability of Seismic Base Isolation
• High Seismic Region and if the Existing Structure is Unsafe
• Life-line Structures
• Structural foundations are Weak and have Low Ductility
•Earthquake motions likely to occur are Short Period Accelerograms
• Primary or important secondary structures are more vulnerable to seismic attack and
to minimise the damage
• Irregular structural form, L-shaped building
• Cost economics of the structure with and without isolators
• Reliable and durable isolator components are available at affordable cost
-
8/17/2019 Base isolation and dampers
17/31
Application in bridges
17
-
8/17/2019 Base isolation and dampers
18/31
18
-
8/17/2019 Base isolation and dampers
19/31
Supplemental damping devices that Dissipates / Absorbs a portion of theenergy input to the structure thus reducing the energy dissipation demandof the primary structure
Damage to the load resisting system is substantially reduced leading to
major reduction in post EQ repair costs
Passive Energy Dissipation (PED) systems (DAMPERS):
Advantages of PED systems:
EQ damaged PED devices can be easily replaced
Ideal for lifeline structures (Structures which are required to functional evenafter EQ)
Effective for wind induced motions also (Unlike Seismic Isolation) 19
-
8/17/2019 Base isolation and dampers
20/31
-
8/17/2019 Base isolation and dampers
21/31
Yielding type ELASTO-PLASTIC energy dissipaters:
The tapered shape of the plate produce uniform
yielding throughout the length
Triangular Device
X - shaped Device
21
-
8/17/2019 Base isolation and dampers
22/31
Lead Extrusion Damping (LED) Device
- Applications (Buildings,Bridges)
22
-
8/17/2019 Base isolation and dampers
23/31
Friction dampersLinear friction dampers
Rotational friction dampers
X-braced damper
23
-
8/17/2019 Base isolation and dampers
24/31
Visco-elastic solid dampers
F
F/2
F/2
Visco Elastic Material
Center Plate
Top & Bottom Cover Plates
24
-
8/17/2019 Base isolation and dampers
25/31
Visco-elastic Fluid Dampers
•Dissipation occurs via conversion of mechanical energy to heat as a piston
deforms a highly viscous substance like silicon gel
•Extremely high energy dissipation is possible by forcing the fluid to pass
through small orifices rather simply deforming the fluid locally
25
-
8/17/2019 Base isolation and dampers
26/31
Spring Friction Damper
•Energy dissipation occurs due to frictional sliding, and consequently the
response is frequency dependent
26
-
8/17/2019 Base isolation and dampers
27/31
27
-
8/17/2019 Base isolation and dampers
28/31
Roof Isolation Systems
A roof isolation system is a combination of rubber
isolators and a damping mechanism between the top
story and the roof or between the top story and rest of
the building.
The top story or the roof acts as a tuned mass damper.
28
-
8/17/2019 Base isolation and dampers
29/31
Roof Isolation System
29
-
8/17/2019 Base isolation and dampers
30/31
30
-
8/17/2019 Base isolation and dampers
31/31
Efficiency of various methods of
DampingThe hysteresis (force-deflection curve) shows the
efficiency of a damper during an earthquake. The (blue)
area inside the curve is the total dissipated energy. The
curve shows that the rotational friction damper
dissipates more energy than any other damper today.
31