Embed Size (px)
Citation preview
www.tarrc.co.uk
Tun Abdul Razak Research Centre (TARRC) A RESEARCH & PROMOTION CENTRE OF THE MALAYSIAN RUBBER BOARD
HIGH DAMPING RUBBER BEARING DESIGN
FOR APPROACH BRIDGE
Kamarudin Ab-Malek
125-year old viaduct bridge in Melbourne Australia, but still heavily trafficked structure
Schematic of 125-year old Melbourne Viaduct
Closed-up view of the rubber pad being squeezed out at the edge
A cut section of the 125-year old rubber from Melbourne Australia – still in good condition
1 division is 1mm
A typical modern rubber bearing for bridges
Pelham Bridge built in 1956 in Lincoln, England Bridge bearings allow the deck to expand and contract
The world’s first bridge installed with rubber bearings
A bearing under the Pelham bridge
www.tarrc.co.uk
A bearing being removed for testing
Albany Court apartment above St. James
Underground Railway Station, London
The world’s first
building installed
with rubber
bearings
to prevent
transmission
of vibrations
caused
by moving trains.
The building was
completed in 1966.
Albany Court apartment built on rubber bearings
over a London underground railway station
•7.2 Richter
•Required more than
US$400 billion to rebuild
Kobe
•The costliest earthquake in
world history
•5,502 killed, 41,527 injured
•300,000 homeless
•100,282 buildings destroyed
•108,402 partially destroyed
1995 KOBE EARTHQUAKE
Kobe 1995 – damages to bridges
FAILED PIVOT BEARING
FAILED PIN BEARING
FAILED STEEL ROLLER BEARINGS
FAILED STEEL BEARINGS
Before Kobe, less than 5% of Japanese bridges installed with rubber bearings. After Kobe, over 95% of newly-built bridges are installed with rubber bearings
NAGOYA BRIDGE, completed in 1999
7 span, box girder, 320m. Isolator 1.6 x 1.6 x 0.24 m
Maximum movement: ± 0.35m
Supporting load: 16 MN/pc
Totsukawa bridge built in 2002
3 span box girder, 175 m
Isolator: 1.7 x 1.6 x 0.3 m
Max movement: ± 0.40 m
Supporting load: 18.8 MN
Nishinomiya bridge
Max movement: ± 0.24 m
Supporting load: 21.4 MN/pc
Built in 2002
Bearing:1.5 x 1.5 x 0.36 m
New structure
Old structure
RESTORATION OF 700m BENTEN SECTION – A continuous span rigidly jointed to piers. Bearings are installed at the bottom of piers – first of its kind
New structure
Metal bearings
THE BEARING IS COVERED FROM BEING DAMAGED
A bearing at the bottom of a pier
RESTORATION OF FUKAE SECTION
•Amplification of forces
• Large interstory drift
• Contents destroyed
• Requires costly repair
• No amplification of forces
• Contents are protected
• No interstory drift
• No costly repair
Base-Isolated Structure Conventional Structure
ground motion
Building’s response
Acceleration Response Spectrum A
ccel
erat
ion
Frequency
Period
Period or Frequency Shift
Tall buildings are inherently safe from earthquake damage
Chi-Chi Taiwan Earthquake on the 21/9/1999 Effect on reinforced concrete buildings
0
500
1000
1500
2000
2500
3000
3500
1 2 3 41-3 4-6 7-11 12-14
Building height (storey)
No of buildings
FOOTHILL COMMUNITIES LAW & SERVICE
CENTRE, SAN BERNADINO, CALIFORNIA USA
First building (4-story) in the world to use natural rubber bearings to withstand up to 8.3 Richter
Completed in 1985 at a cost of US$38 Million
Total number of bearings are 98
The owner of the building, San Bernadino County, decided on base isolation on the 11th hour - a bold decision considering this is the first in the world
INSTALLED BEARINGS UNDERNEATH A BUILDING
A SEISMIC BEARING BEING SHEARED AND COMPRESSED TO SIMULATE EARTHQUAKE
USC UNIVERSITY HOSPITAL
LOS ANGELES, CALIFORNIA, USA
• Completed May 1991, construction cost US$50 Million
• Seven stories and sits on 149 rubber bearings (1.5%)
• Performed very well during and after 1994 Northridge
earthquake
• Northridge earthquake was the most costly in the US
history: US$50 billion
• 31 other hospitals in LA
suffered significant
damage,
• 9 hospitals required full
evacuation
B
1
2
3
4
5
6
7
Am
pli
fica
tio
n o
f fo
rces
0.11g
0.13g
0.37g
0.49g
Using Rubber Bearings USC required no repair and operational before and after the earthquake
1.30g
0.40g 0.40g
Conventional LA County General Hospital Suffered US$400 million damage
Am
pli
fica
tio
n o
f fo
rces
Comparison between the two hospitals
70% reduction in force 225% increase in force
WEST JAPAN POSTAL SERVICE
COMPUTER CENTRE IN KOBE
6 Story,
500,000 sq ft space,
supported on
120 bearings
Response during Kobe’s 1995
Isolated Conventional
Ground 0.30g 0.27g
6th Floor 0.10g 0.97g
67 %
reduction
260 %
amplification
MATSUMURA GUMI TECHNICAL RESEARCH CENTER
Response during Kobe’s 1995
Isolated Conventional
Ground 0.28g 0.28g
Roof 0.20g 0.98g
29 %
reduction
250 %
amplification
Earthquakes around Malaysia 1897-2004
www.tarrc.co.uk
www.tarrc.co.uk
WHY WE IN MALAYSIA SHOULD NOT BE COMPLACENT TO EARTHQUAKES
• Damaging earthquakes had taken place in unexpected places around the world • 1989 in Newcastle near Sydney Australia, causing US15 billion damage • 1993 Maharastra, India 30,000 people killed • 1985 Mexico city, epicentre 400km away • 1976 Tansang, China killing 250,000 killed
www.tarrc.co.uk
Can the 2nd Penang Bridge withstand future
damaging earthquakes?
www.tarrc.co.uk
Site Specific Ground Response Spectra
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.01 0.1 1 10
Spe
ctra
l acc
ele
rati
on
(g
)
Period (s)
TR2500, ζ = 5%
TR475, ζ = 5%
www.tarrc.co.uk
Seismic Loadings
1. Earthquake events a) Design Earthquake: 475 year return period Bridge structures may need minor repairs b) Maximum Credible Earthquake: 2500 years return period. Should not result in collapse of the bridge 2. Seismic Response Spectra Report on Seismic Hazard Assessment for Penang
Bridge Peak Bedrock Accelerations (PBA) of the Design Earthquake
PBA= 0.056 g for 475 year return period PBA=0.11g for 2500 year return period
www.tarrc.co.uk
Typical Sea Section Span Configuration
bearings
Original design uses pot bearings adequate for 475
Under 2500 failure in the piles and the deck
www.tarrc.co.uk
Nonlinear Time History Analysis
Bilinear model for
the Isolators
k1= 12.8 kN/mm
k2 = 3.94 kN/mm
dy = 14.5 mm
Seismic Analysis
Model for piers
P45 to P51
Adjacent span effect
included
Time History
(TR 2500) at
surface borehole
www.tarrc.co.uk
Results of Time History Analysis carried out by Highway Planning & Design Institute
(Tongji University) on P45 to P51
1. By using high damping rubber bearings the approach span piling system would be able to withstand the impact of 2500 year return period earthquake,
2. The results also show that the superstructure of
the approach span is well protected by the rubber bearings from the 2500 year return period earthquake
www.tarrc.co.uk
Design Criteria
1. Design Life of 120 years with serviceable life of 25 years- BS5400 2. Design Standards Non Seismic Condition: BS5400 : 1983 Part 9 Bridge bearings (non-seismic conditions) Seismic Conditions: EN 1990 0 Basis of Structural Design EN 1998 8 Design of Structures for Earthquake Resistance 1998-1 General rules, Seismic design for Building 1998-2 Bridges 1998-2 section 7 augmented by EN 15129 Anti-seismic devices
www.tarrc.co.uk
Bearings SLS Data Bearing Identification mark E1 E2 E3 E4
Loads [KN]
Vertical
Permanent 6800 7000 3400 6900
Maximum 13500 13950 8000 13600
Minimum 5000 5300 2150 5100
Translat- ions [mm]
Transverse Reversible Wind 50 50 50 50
Reversible Traffic 15 15 20 15
Longitudinal
Reversible Wind 20 20 20 20
Reversible Traffic 10 10 10 10
Reversible Temperature 10 15 20 5
Irreversible Creep & shrink 50 100 140 5
Rotation [radians]
Longitudinal
Permanent + 0.004 + 0.004 + 0.009 + 0.004
Live + 0.004 + 0.004 + 0.005 + 0.004
– 0.002 – 0.002 – 0.002 – 0.002
Transverse Live ± 0.002 ± 0.002 ± 0.002 ± 0.002
www.tarrc.co.uk
Bearings SLS Data Bearing Identification mark E1 E2 E3 E4
Loads [KN]
Vertical
Permanent 6800 7000 3400 6900
Maximum 13500 13950 8000 13600
Minimum 5000 5300 2150 5100
Translat- ions [mm]
Transverse Reversible Wind 50 50 50 50
Reversible Traffic 15 15 20 15
Longitudinal
Reversible Wind 20 20 20 20
Reversible Traffic 10 10 10 10
Reversible Temperature 10 15 20 5
Irreversible Creep & shrink 50 100 140 5
Rotation [radians]
Longitudinal
Permanent + 0.004 + 0.004 + 0.009 + 0.004
Live + 0.004 + 0.004 + 0.005 + 0.004
– 0.002 – 0.002 – 0.002 – 0.002
Transverse Live ± 0.002 ± 0.002 ± 0.002 ± 0.002
www.tarrc.co.uk
Bearings SLS Data Bearing Identification mark E1 E2 E3 E4
Loads [KN]
Vertical
Permanent 6800 7000 3400 6900
Maximum 13500 13950 8000 13600
Minimum 5000 5300 2150 5100
Translat- ions [mm]
Transverse Reversible Wind 50 50 50 50
Reversible Traffic 15 15 20 15
Longitudinal
Reversible Wind 20 20 20 20
Reversible Traffic 10 10 10 10
Reversible Temperature 10 15 20 5
Irreversible Creep & shrink 50 100 140 5
Rotation [radians]
Longitudinal
Permanent + 0.004 + 0.004 + 0.009 + 0.004
Live + 0.004 + 0.004 + 0.005 + 0.004
– 0.002 – 0.002 – 0.002 – 0.002
Transverse Live ± 0.002 ± 0.002 ± 0.002 ± 0.002
www.tarrc.co.uk
Bearings ULS Data – 2500 year return
Bearing Identification mark E1 E2 E3 E4
Loads [KN] Vertical Max 2200 2200 1100 2200
Min -2200 -2200 -1100 -2200
Translations [mm] Transverse 100 100 100 100
Longitudinal 100 100 100 100
Rotation [radians] Longitudinal 0.010 0.010 0.012 0.010
Transverse 0.001 0.001 0.001 0.001
www.tarrc.co.uk
Bearings Location within 6 Spans Modules
E3
E3
E3
E3
E3
E3
E3
E3
E2
E2
E2
E2
E2
E2
E2
E2
E1
E1
E1
E1
E1
E1
E1
E1
E4
E4
E4
E4
Centreline of bridge
Key
E1 HDRB
E3 HDRB with preset
www.tarrc.co.uk
Bearing design was governed by 3 parameters
1. Conditions imposed by EN1529 and BS5400 2. Maximum bearing dimensions because of limited space on top of piers 3. The period of the bridge is aimed to be 2 seconds
T = 2π(M/K)½
M= mass of structure
K= shear stiffness of rubber bearings
www.tarrc.co.uk
Bearings details and properties • Type 1 bearings - E1, E2 and E4 only differ in preset displacement • Type 2 bearings - E3, smaller plan area to achieve lower shear stiffness • 15 rubber layers of 16mm thickness • 14 steel reinforcing layers of 5mm thickness • 20mm thick steel endplates and 10mm rubber side cover layers
E4 E1 E2 E3
Length (mm) 1050 1050 1050 850
Width (mm) 850 850 850 700
Height (mm) 350 350 350 350
Preset Displacement (mm) locked 0 50 70
Shear Stiffness 44% strain (kN/mm) 5.0 5.0 5.0 3.3
Nominal Vertical Stiffness (MN/mm) 3.2 3.2 3.2 1.7
Shape Factor 14.4 14.4 14.4 11.7
The test facility : • 2000 tons compression • 200 tons shear load • +/- 500mm shear displacement
www.tarrc.co.uk
COMPRESSION TEST
www.tarrc.co.uk
Compression test force-deflection curve
www.tarrc.co.uk
Compression stiffness test for prototype Type 1 bearing
Force (kN) Displacement (mm) Vertical Stiffness (kN/mm)
Visual Inspection Force 1 Force 2 Displacement 1 Displacement 2
13689.2 4519.4 8.931 5.338 2552.1 No defects
13870.5 4629.1 8.900 5.213 2506.5 No defects
Average Vertical Stiffness (kN/mm) 2529.3
Test Temperature (°C) 32
EN 15129 requires to report this prototype compression stiffness. The vertical stiffness of production bearings must be within 30% of this.
www.tarrc.co.uk
Compression stiffness test for prototype Type 2 bearing
Force (kN) Displacement (mm) Vertical Stiffness (kN/mm)
Visual Inspection Force 1 Force 2
Displacement 1
Displacement 2
7841.3 2606.2 8.287 4.988 1586.9 No defects
8059.6 2661.2 8.987 5.525 1559.3 No defects
Average Vertical Stiffness (kN/mm) 1573.1
Test Temperature (°C) 32
www.tarrc.co.uk
SHEAR TEST PREPARATION TAKES ABOUT 4 HOURS
www.tarrc.co.uk
Bearings are ready for the shear test
www.tarrc.co.uk
SIMULTANEOUS COMPRESSION AND SHEAR
www.tarrc.co.uk
SIMULTANEOUS SHEAR AND COMPRESSION TEST
www.tarrc.co.uk
Shear Stiffness and Damping Ratio for prototype Type 1 bearing
Shear Displacement
(mm)
Shear Stiffness (kN/mm)
Damping Ratio (%)
±12 11.3 20.8 ±24 8.9 18.3 ±48 6.7 15.0
±104 5.5 (4.0 to 6.0) 12.5 (9.5 to 14.5) ±180 4.9 10.9 ±210 4.6 10.6
www.tarrc.co.uk
Shear Stiffness and Damping Ratio for prototype Type 2 bearings
Shear Displacement
(mm)
Shear Stiffness (kN/mm)
Damping Ratio (%)
±12 8.4 18.8 ±24 6.0 16.7 ±48 4.9 14.8
±104 3.9 (2.6 to 3.9) 12.2(9.5 to 14.5)
±180 3.5 10.5 ±240 3.1 9.6
www.tarrc.co.uk
Test load in compression for lateral capacity test Bearings are sheared to 297mm
Bearing Type Compression Load
(kN)
Type 1 5800
15050
Type 2 2300 9800
The bearings undergo simultaneous shear and compression. At 297mm shear the bearings were inspected and no sign of surface cracks and imperfection
Bearings undergoing 297mm deflection with 15050kN compression load
www.tarrc.co.uk
Shear Stiffness Distribution Plot for Type 1 Production Bearings (----- indicates upper and lower bound of the
design value)
www.tarrc.co.uk
Shear Stiffness Distribution Plot for Type 2 Bearings
(----- indicates upper and lower bound of the design value)
www.tarrc.co.uk
Damping Ratio Distribution Plot for Type 1 Production Bearings (----- indicates upper and lower bound of the
design value)
www.tarrc.co.uk
Damping Ratio Distribution Plot for Type 2 Production Bearings (----- indicates upper and lower bound of the design value)
www.tarrc.co.uk
Bearings Location within 6 Spans Modules
E3
E3
E3
E3
E3
E3
E3
E3
E2
E2
E2
E2
E2
E2
E2
E2
E1
E1
E1
E1
E1
E1
E1
E1
E4
E4
E4
E4
Centreline of bridge
Key
E1 HDRB
E3 HDRB with preset
www.tarrc.co.uk
Bearings under shear so that preset locking plates can be installed
www.tarrc.co.uk Patent Application Submitted
Installed bearings with preset locking plates
www.tarrc.co.uk
Bearings with locking plates removed
Patent Application Submitted
www.tarrc.co.uk
Physical properties of the High Damping Rubber
Property Test Results Requirement Test Method
Tensile Strength MPa, min 22 12 ISO 37 Type 2
Elongation at break %, min 521 400 ISO 37 Type 2
Tear resistance kN/m, min 15 7 ISO 34a Method A
Compression set 70°C, 24h, max 22 60 ISO 815 Type A
25% compression
Ozone resistance Elongation 30% - 96h
40°C ± 2°C Concentration: 25pphm
No cracks No cracks ISO 1431/1
Accelerated air oven ageing 7 days at 70°C
Maximum change from unaged value: Hardness (IRHD)
Tensile strength (%) Elongation at break (%)
+3 +0.5
-8
-5, +8 ±15 ±25
ISO 188, Method A
ISO 48 ISO 37 Type 2 ISO 37 Type 2
Dynamic testing of rubber
Rubber sample
www.tarrc.co.uk
Dynamic shear modulus and damping (3rd cycle) carried out at 0.5Hz frequency
Rubber Shear Strain(%)
Shear Modulus G(MPa)
Damping Ratio, (%)
5 3.00 16.0
10 2.04 14.3
20 1.84 12.2
44 1.43 10.4
50 1.36 10.1
80 1.20 9.5
100 1.17 9.1
150 1.20 8.4
www.tarrc.co.uk
Test results for effect of frequency (3rd cycle) and at ±100% amplitude
Frequency (%)
Damping Ratio,
(%)
Difference from the value at
0.5Hz (%)
0.1 10.1 1.9
- 0.5 10.3
4.9 2.0 10.8 -
www.tarrc.co.uk
Effect of anaerobic ageing on shear modulus (3rd cycle)
Ageing Condition
14 days at 70°C
Shear Modulus, G
(MPa)
Difference (%)
Before ageing 1.54 +12.3
After ageing 1.73
Ageing Condition
14 days at 70°C
Damping Ratio,
(%)
Difference (%)
Before ageing 11.3 -6.2
After ageing 10.6
Effect of anaerobic ageing on damping ratio (3rd cycle)
www.tarrc.co.uk
Test results for stability under repeated cycling
Cycle Shear
Modulus, G (MPa)
Damping Ratio,
(%) 1 1.31 12.5 2 1.28 11.9 3 1.26 11.8 4 1.25 11.7 5 1.24 11.6 6 1.24 11.6 7 1.23 11.5 8 1.23 11.6 9 1.23 11.5
10 1.22 11.5
www.tarrc.co.uk
Ratio of shear modulus and damping ratio
Ratio Requirement
Minimum G (cycles 2-10) 1.22 0.95 >0.7
Maximum G (cycles 2-10) 1.28 Minimum (cycles 2-10) 11.5
0.97 >0.7 Maximum (cycles 2-10) 11.9 Minimum G (cycles 1-10) 1.22
0.93 >0.6 Maximum G (cycles 1-10) 1.31
www.tarrc.co.uk
Crack extension within 24 hours
Test Piece Crack
extension Requirement
1 0.634 <3mm 2 0.520 <3mm 3 0.310 <3mm
www.tarrc.co.uk
Semi intelligent bearings: the stiffness varies with different strains
0
2
4
6
8
10
12
0 50 100 150 200 250
She
ar S
tiff
ne
ss (
kN/m
m)
Displacement Amplitude (mm)
ss
Stiff under normal condition
Soft under large strains
Type 1 bearing
Type 2 bearing
www.tarrc.co.uk
ACKNOWLEDMENTS
Hamid Ahmadi, Dr A Muhr, Dr Julia Gough, I. Stephen and J. Pickens, Tun Abdul Razak Research Centre, UK Dr Nazirah Ahmad, Lee Jiang Jun and Mohammad Umar Zulkefli Rubber Technology Centre, Sg Buloh
www.tarrc.co.uk
Thank you for
your attention
