Laminated Rubber Bearing Properties

International Conference on Interdisciplinary Approaches in Civil Engineering for Sustainable Development (IACESD-2023)
1
International Conference on Interdisciplinary Approaches in Civil Engineering for Sustainable Development
(IACESD-2023)
1. Bharat Chalise (Presenting Author)
Email: naturead@gmail.com
Predicting the Porosity of SCM-blended Concrete Composites Using Ensemble
Machine Learning Models
Affiliation 1,: Department of Civil
Engineering, Indian Institute of
Technology Delhi
Experimental and Numerical Study on Hysteretic Behavior of Laminated
Rubber Bearing under Quasi Static Loading and its Performance on
Secondary System

2
Introduction
● Base-isolation (seismic isolation) a widely used
technology to isolate superstructure from the ground
by intercepting earth vibration with the help of
isolators
● The laminated rubber bearing (LRB), and lead core
rubber bearings are used extensively in practice.
● Laminated rubber bearings consist of alternate
layers of rubber and metal plates.
Fig. Response Spectrum of base-Isolation

3
Literature Survey
• Numbers of studies are being carried out to analyze the effects of bearing properties in base-isolated
structures. Zhou et al. (2022 ), generalize the laminated rubber bearing through equivalent
linearization. (San Jing et al. 2021, Barbat et al. 1997; Mallikarjun et al. 2013; Kely and Hseing, 1985;
Khechfe et al. Konstantinos et al. 2017; Zhang et al. 2022.) investigated the effects of LRB on
secondary structures in nuclear plant. Result shows equivalent linearization predicts the accurate
results on laminated rubber bearings.
• The performance of the laminated bearing is influenced by various factors such as geometric
properties, types of material and loading history Naeim and Kelly (1999), Matsagar and Jangid (2004)
concluded the response of base-isolated structure is significantly influenced by the shape of hysteresis
loop of isolator
•

4
Objectives
1. To study hysteretic behavior of laminated rubber bearing under quasi-static loading
2. To identify the shear and vertical stiffness of the rubber bearing through laboratory
testing
3. Characterization of the laminated rubber bearing and identification of linear and non-
linear properties of LRB
4. To investigate the effect on base-isolated secondary structures

5
Test Specimen (Laminated Rubber Bearing)
❖ The test was conducted using a square-shaped laminated rubber bearing with the dimensions
shown in Figure. The specimen (50 mm × 50 mm × 50 mm) consists of steel and rubber plates
bonded together in alternate layers. 12 mm thick steel plates were used as top and bottom plates.
The bearing consisted of 5 numbers of 6 mm rubber layer and 4 numbers of 1.5 mm steel shims
with dimension 40 mm × 40 mm × 1.5 mm. The rubber used in the bearing neoprene with IRHD
value of 47.
Fig. Speciment LRB

6
Test Setup
• Quasi-static manual loading through hydraulic pump connected with jack was used. A load cell of
capacity 10 ton (100 kN) with rating 3.06 mV/V was connected in between hydraulic pump and the
load plate. LVDT with stroke length +5 mm was connected on the opposite side of loading system,
on top plate of bearing. Strain smart 7000 software was used to calibrate the instruments,
process, and acquisition of the data.
Fig: Laboratory Setup for Shear test
Fig: Laboratory Setup for Vertical Stiffness Test

7
Test Result (Shear Test)
-200
-100
0
100
200
-4 -3 -2 -1 0 1 2 3 4
-200
-100
0
100
200
-4 -3 -2 -1 0 1 2 3 4
0 kg Compressive axial load
Unloading
Loading
Force
(N)
Unloading
Loading
Loading
Unloading
Force
(N)
Displacement (mm)
Unloading
Loading
Displacement (mm)
Fig: Force-displacement curve (hysteresis loop) of type 1A bearing at different axial compressive loading conditions.
Damping in the system is small (narrow-band system),
stiffness can be obtained with an approximate solution using
the method of equivalent linearization
It is observed that lateral stiffness of laminated rubber bearing
decreases with increase in axial compressive loads

8
Test Result (Vertical Stiffness test)
 Vertical stiffness is one of the key parameters in the design of both seismic isolation
bearings and bridge bearings. For this reason, the prediction of the behavior of
multilayered elastomeric bearings under compressive loads is considerably important
for their design
Here, α,β and A are the constants governing scale and general shape of the hysteretic loop while the smoothness of the force
displacement curve is govern by n (Wen, 1980). Tune the experimental hysteretic loop with analytical by Wen, 1980 Obtain the non-
linear hysteretic parameters
Linear Parameters
Non-linear Parameters
(Dimensionless)
𝑘𝑒𝑓𝑓
(N/mm)
𝑓𝑦
(N)
𝛥𝑜
(mm)
𝜁
(%)
𝑘𝑣
(N/mm)
n  𝛽 𝐴 𝛾
52 80 3 6.0 7990 1 0.6 0.6 1 1
)
(
)
(









F
F
keff
Effective stiffness
0 1 2 3
0
5
10
15
20
25
30
Vertical
load
(kN)
Vertical displacement (mm)
Fig: Force-displacement curve (hysteresis loop) for vertical test

9
Numerical Investigation
❖ The fixed based five storied primary structure (PS) modelled with finite element software. Similarly,
single degree of freedom system secondary structure (SS) modeled by mounting in five different floor
levels.
The earthquake motions selected for the study are Sinusoidal motion with 3Hz amplitude, Loma Prieta earthquake (1989),
Northridge Earthquake (1994) and Kobe Earthquake (1995)
(a) Five-story primary structure (b) Secondary structure (c) Mathematical model of five storied primary structure with base-
isolated secondary structure (d) Laboratory setup of secondary structure installed on the first floor of the primary structure

10
Results and Discussion
-1.0
-0.5
0.0
0.5
1.0
0 5 10 15 20 25
-1.0
-0.5
0.0
0.5
1.0
0 5 10 15 20 25
Top
floor
acceleration
(g)
Fixed base
Base-isolated
Type I SS
Type 1A bearing Type 1B bearing
Type 2A bearing Type 3A bearing
Time (sec)
-0.5
0.0
0.5
0 5 10
-0.5
0.0
0.5
0 5 10
Type 1A bearing
Top
floor
acceleration
(g)
Fixed base
Base-isolated
Type 1B bearing
Type 2A bearing
Type I SS
Type 3A bearing
Time (sec)
Time (Sec)
a) Top floor acceleration response time histories of the SS isolated with
type 1A bearing for Imperial Valley, 1940 base excitation b) Top floor
acceleration response time histories of the type I SS isolated with type
1A bearing for sinusoidal base excitation of amplitude 4 mm and
frequency 3 Hz
For sinusoidal base excitations, It is seen
that less the stiffness of the bearing more
the acceleration on the top floor than in
fixed base condition is noted (for type 1A
bearing increment up to 10%)
For same set up, top floor acceleration is
seen significantly decreased (up to 51%) in
case of earthquake excitation
It can be concluded that effectiveness of
the isolation systems (regardless type)
equally depends upon the base excitation
signals

11
❖ Response of bearing when secondary structure mounted on first and fifth floor of primary structure
5 10 15 20 25
-4
-2
0
2
-2
0
2
-2
0
2
Linear
Non-linear
2.77
2.53
Loma Prieta, 1989
Top
floor
acceleration(g)
2.0
2.05
Time (sec)
Kobe, 1995
Northridge, 1994
1.66
1.42
-2
0
2
-2
0
2
0 5 10 15 20 25
-4
-2
0
2
Loma Prieta, 1989
2.01
2.05 Linear
Non-linear
Top
floor
acceleration(g)
1.66
1.42
Time (sec)
Kobe, 1995
Northridge, 1994
2.53
2.39
(a) SS top floor acceleration when SS mounted on first floor of primary structure (b) SS top floor
acceleration when SS mounted on fifth floor of primary structure

12
❖ Response of bearing when secondary structure mounted on first and fifth floor of primary structure
(a) Bearing displacement when SS mounted on first floor of primary structure. (b) Bearing displacement when
SS mounted on fifth floor of primary structure
-10
0
10
-10
0
10
0 5 10 15 20 25
-20
-10
0
10
20
Loma Prieta, 1989
Linear
Non-linear
13.61
9.20
Northridge, 1994
Bearing
displacement
(cm)
6.43
8.47
Kobe, 1995
Time (sec)
12.51
15.91
-10
0
10
-10
-5
0
5
10
0 5 10 15 20 25
-20
-10
0
10
20
Linear
Non-linear
Loma Prieta, 1989
Northridge, 1994
Kobe, 1995
9.21
13.61
Bearing
displacement
(cm)
6.43
8.47
Time (sec)
15.91
12.51

13
❖ Shear force induced in bearing at different floor levels shows that there is marginal difference in the response as shown in
Figure
Shear force induced in the bearings when SS placed at different floor levels.
0 1 2 3 4 5 6
0
2
4
6
8
10
12
Loma Prieta, 1989
Shear
Force
(kN)
Floor Level
Linear
Non-linear
0 1 2 3 4 5 6
0
2
4
6
8
Northridge, 1994
Floor Level
Linear
Non-linear
0 1 2 3 4 5 6
0
2
4
6
8
Kobe, 1995
Floor Level
Linear
Non-linear

14
Conclusions
• The shear test result with varied axial loads demonstrated that, laminated rubber bearing exihibits
marginal reduction of shear stiffness up to 7% with increase in axial load.
• The response of base isolated secondary structure is significantly affected by hysteretic properties
of the bearing. Equivalent linearization can be done for narrowly damped laminated rubber
bearings for conservative results, however for actual prediction of the response, size and shape of
the hysteretic loop should be considered. No significant differences in responses in shear force
indicate that linearization is a perfect way to characterize laminated rubber bearings.
• For earthquakes time history response reduced as much as 51% however, unable to perform well
with 3Hz sinusoidal excitation. It can be concluded that effectiveness of the isolation systems
(regardless type) equally depends upon the base excitation signals

15
References
1. Barbat, A. H., and L. M. Bozzo: Seismic Analysis of Base-Isolated Buildings. Archives of Computational Methods in Engineering 4 (2), pp. 153-192(1997).
2. Datta, T. K.: Seismic Analysis of the Structures, John Wiley and Sons (Asia) Pte Ltd (2010).
3. Kelly, J. M., and Hsiang C. T.: Seismic Response of light Internal Equipment in Base Isolation Structures, Earthquake Engineering and Structural Dynamics, 13(6), pp. 711-732 (1985).
4. Khechfe H., Mohammad N., Zhikun H., James M. K. and Goodarz Ahmadi: An Ex-perimental Study on the Seismic Response of base-isolated secondary systems, Jour-nal of Pressure Vessel
Technology (2002).
5. Konstantinos N. Kalfas, Stergios A. Mitoulis.: Performance of steel-laminated rub-ber bearings subjected to combinations of axial loads and shear strains, Procedia En-gineering, 199, pp. 2979-
2984,1877-7058, https://doi.org/10.1016/j.proeng.2017.09.533 (2017).
6. Mallikarjun, P. V. Jagtap P., Kumar P, and Matsagar V. A.: Performance of Seismic Base-Isolated Building for Secondary System Protection under Real Earthquakes, Conference on Structural
Mechanics in Reactor Technology (2013).
7. Matsagar, V. A. and Jangid, R. S.: Influence of isolator characteristics on the re-sponse of base-isolated structures. Engineering Structures, 26, pp. 1735-1749 (2004).
8. Naeim, F. and Kelly, J. M.: "Design of seismic isolated structures." John Wiley & Son, Inc., New York (1999).
9. Sang Jin Ma , Tae-Myung Shin, Ju-Seung Ryu, Jin-Hyeong Lee and Gyeong-Hoi Koo : Experimental Approach for the Failure Mode of Small Laminated Rubber Bearings for Seismic Isolation of Nuclear
Components, applied sciences, 12(1), 125 (2021).
10. Solva, C. W.: Vibrations Fundamentals and Practice. Florida, CRC Press (2007).
11. Wen, Y. K.: Equivalent Linearization for Hysteretic Systems under Random Excita-tion, Journal of Applied Mechanics, 47 (1), pp. 150-154 (1980).
12. Wen, Y. K.: Method for Random Vibration of Hysteretic System, Journal of the En-gineering Mechanics Division (1976).
13. Zhang B, Wang K, Lu G, Qiu W, Yin W. Experimental and Seismic Response Study of Laminated Rubber Bearings Considering Different Friction Interfaces. Buildings. 12(10):1526.
https://doi.org/10.3390/buildings12101526 (2022)
14. Zhiguang Zhou, Yiwen Li, Xiaorong Hu.: Analysis method of isolation layer com-posed of high damping rubber bearings based on deformation history integral type model, Engineering Structures, 25,
https://doi.org/10.1016/j.engstruct.2021.113553 (2022).

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