ctt pot bearings
TRANSCRIPT
-
8/12/2019 CTT Pot Bearings
1/16
-
8/12/2019 CTT Pot Bearings
2/16
CONTENTS
1. General page 3
2. Specif ications and designparameters page 4
3. Informat ion required for designof POT bearings page 5
4. Dimensions data sheets
- POT bearing type PU page 6
- POT bearing type PL page 7
- POT bearing type PF page 8
5. Accessories page 9
6. Site installation page 10
7. POT bearings for incrementally
launched bridges page 11
8. Special POT bearings page 12
9. Recent bridge structures page 13
10. Quality control and tests page 15
2
-
8/12/2019 CTT Pot Bearings
3/16
Structural bearings are required to connect different parts
of a structure such as bridge decks to piers and
abutments. The most widely-used structural bearings
are plain or reinforced elastomeric bearings, and POT
bearings. They are capable of transmitting forces while
absorbing the structures deformations and rotations.
The strength of reinforced elastomeric bearings is limited
by the shear properties of the elastomeric block,
especially when the three stresses, compression, shear
and bending, occur at the same time. POT bearings
maximise the shear strength of the bearings elastomer
by encasing it in a steel cylinder. They can accept working
loads in the elastomer, which, in turn, allows the
bearings dimensions to be reduced.
POT bearings are divided into three main types,
depending on restrictions to the structures
deformations: type PF (fixed), type PL (free or unguided
sliding), and type PU (guided sliding).
In all types, under vertical load, the upper plate acts on
the elastomer like a piston on a hydraulic cylinder, and
the elastomer itself, perfectly sealed, behaves like a
viscous fluid, offering minimal resistance to rotation
around any horizontal axis. No sliding movement isallowed in type PF (fixed).
Type PL (free sliding) is obtained by dividing the upper
plate into two independent elements: rectangular sliding
plate and circular piston. The sliding ability is achieved
by combining the following three materials into the
sliding system:
ILM bridge pot bearing type
- Polished stainless steel (mirror finishing) welded
to the bottom side of the rectangular sliding plate.
- Circular dimpled PTFE disc recessed to half of its
thickness in the piston. Minimum protrusion is given
to grant full contact with stainless steel at any time.
PTFE displays excellent resistance to fatigue, impact
and ageing.
- Special lubricant grease: silicone base. This grease
fills the dimples in the PTFE disc ensuring a permanent
very low friction system coefficient and preventing
abrasion of PTFE.
The combination of these three materials gives a regular
range of friction coefficient between 1% and 3%.
Type PU (guided sliding) is obtained by assembling a
guide bar, either welded or bolted, on top of the piston.
The guide bar slides along a longitudinal recess in the
sliding plate, thus avoiding transverse movement.
Contact between guide bar and sliding plate consists of
special composite material (DU-metal) fixed to the guide
bar and stainless steel backed to the sliding plate,
ensuring a minimum friction coefficient.
Neoprene bearing
3
1. General
-
8/12/2019 CTT Pot Bearings
4/16
2. Specifications and design parameters
4
BASIC DESIGN PARAMETERS
UPPER PLATE
Load distribution at 60
The length of the upper plate must
grant a proper load distribution in the
concrete in the event of max. design
movement
L5 = D6 + 2 Ex + 2T5/3+50
Where :
D6 diameter of PTFE discEx Max. design movement
T5 Thickness of upper plate
P.T.F.E.
Average allowable stress at SLS undermax. vertical load D1/50>12mm
DOWELS -STUDS
In order to grant a safety factor not
less than 1,5 against sliding, the
following condition must be verified::
/S*Vmin+n*Hd>Zh
where :
= 0.5 Steel-concrete friction coefficient
S = 1.5 Safety factor
n Number of dowels ( or studs)
Hd Shear capacity of each dowel
MATERIALS
STANDARD SPEClFlCATlONS
TOP PLATE
Quality steel St37 or
St52 according to
DIN 17.100
Stainless steel
according to AISI 304
LUBRICANT
Silicone grease type 300
P.T.F.E.
P.T.F.E. pad with dimples accordingASTM D1457-91 a Type 1
Grade 2BS 3764 Grade A
GUIDE
Quality steel St37 orSt52 according to
DIN 17.100
DU-metal
EXTERNAL SEALING
RING
Spongy neoprene
PISTON
Quality steel St37 orSt52 according to
DIN 17.100
INTERNAL SEALING
RING
Double gasket brass ring
ELASTOMER PAD
Natural rubber accordingAASHTO 50Sh+-5
POT (STEEL RING +
BASE PLATE)
Quality steel St37 or
St52 according to
DIN 17.100
ANCHOR SOCKETS
Galvanized bolts
Steel CK35 according
DIN 17.200
-
8/12/2019 CTT Pot Bearings
5/16
It should be pointed out that the cost of the POT bearings
varies with the changes in design parameters. Forinstance the allowable bearing pressure on the concrete,
has a maj or influence. It depends on the characteristic
concrete strength, Br and the relation between the
diameters of direct circular loaded area (D2) and circular
enlarged area, with the same centre of gravity, lying totally
within the top support area (D) (see figure). The following
design rules are proposed for the allowable bearing
pressure on concrete :
5
3. Information required for the design of POT bearings
Dimensions given in the section 4 tables are indicative,
representing a presizing of the three different types of POT
bearings. They are given to make the design engineers
work easier and should be used with caution, bearing in
mind that they are calculated from the following assumed
design parameters:
Al lowable concrete pressure
Pier : 20 N/mm 2 Deck : 20 N/mm2
Rotation = 0.01 rad.
Loads and movements
1.- Free sliding type PL
1.1 Hxmax= 3 % of Vmax.
1.2 Hymax = 3% of Vmax.
1.3 Ey= +- 10mm.
1.4 Ex= * 50mm.
2.- Guided slid ing type PU
2.1 Hxmax= 3 % of Vmax
2.2 Hymax = 5% of Vmax
2.3 Ey= 0 always
2.4 Ex= +- 50mm.
3.- Fixed type PF
3.1 Hxmax = 5% of Vmax
3.2 Hymax = 5% of Vmax
3.3 Ey= 0 always
3.4 Ex= 0 always
4.- For every type
4.1 Vg = 70% Vmax
4.2 Vmin = 50% Vmax
4.3 Hxg = 90% Hxmax
4.4 Hyg = 90% Hymax
4.5 Hxmin = 70% Hxmax
4.6 Hymin = 70% Hymin
Our Technical Department is at your disposal to supply any
specific information in order to assist you from the early
design stage. To assess the optimum POT bearing
dimensions for your application and to carry out a detailed
design, we need the following information:
Project: Bearing type :
Loads:
Load c as e Vmax.
Vmax: kN Hx: kN Hy: kN
Lo ad c as e Vg . ( pe rmane nt l oad)
Vg: kN Hxg: kN Hyg: kN
Lo ad c as e Vmin.
Vmin: kN Hx: kN Hy: kNRotation and movement :
Ex+-: mm. Ey +-: mm. Rotation: rad.
Al lowablebearIng pressure on concrete :
Pier : MPa Deck : MPa
1 .- For direct distribution from the pot to the concrete:
b= Br * D < 1, 4 *Br
1, 8 D2
2.- For distribution plates through masonry plates
between pot and concrete:
b= Br * D < 1, 0*Br
2, 1 D2
3.- For distribution through sliding plates:
b= Br * D < 0, 9 *Br
2, 3 D2
Bursting reinforcement to be designed in SLS for a total
force of:
with the allowable stress in reinforcement between
18 0 MPa and 200 MPa according to the steel grade.
Technical departement in the factory
-
8/12/2019 CTT Pot Bearings
6/16
4. Dimensions data sheets
6
POT bearing type PU
This type of bearing :
- Allows longitudinal movements
- Constrains transversal movements
- Bears horizontal transversal loads
BEARING TYPE
PU-100
PU-200
PU-300
PU-400
PU-500
PU-600
PU-700
PU-800PU-900
PU-1000
PU-1200
PU-1400
PU-1600
PU-1800
PU-2000
PU-2400
PU-2800
PU-3000
PU-3500
PU-4000
PU-4500PU-5000
TH
8 0
8 1
8 5
8 4
98
96
102
106119
115
122
131
198
154
153
161
18 0
170
192
190
196216
L5
393
478
538
608
665
719
768
8 148 57
8 98
975
1045
1110
1171
1229
1337
1436
1515
1593
1705
17931885
B5
293
378
438
508
565
719
768
8 148 57
8 98
975
1045
1110
1171
1229
1337
1436
1515
1593
1705
17931885
oD2
293
378
438
508
565
619
668
714757
798
8 75
945
1010
1071
1129
1237
1336
1415
1493
1605
1693178 5
DP
256
316
360
408
450
501
536
568599
628
68 2
732
778
8 21
8 62
938
1008
1064
1120
1199
12601325
DL
200
200
200
250
250
300
300
300300
300
350
350
350
350
350
350
350
350
350
350
350350
DM
40
40
40
50
50
60
60
6060
60
70
70
70
70
70
70
70
70
70
70
7070
DIMENSIONS IN mm
NOTE : The dimensions given in the tables are indicative. Design and dimensions may be modified by CTT without prior notification.
DL
TH
DL
-
8/12/2019 CTT Pot Bearings
7/16
7
BEARING TYPE
PL-100
PL-200
PL-300
PL-400
PL-500
PL-600
PL-700
PL-800
PL-900
PL-1000
PL-1200
PL-1400
PL-1600
PL-1800
PL-2000
PL-2400
PL-2800
PL-3000
PL-3500PU-4000
PL-4500
PL-5000
TH
74
79
8 5
96
98
96
110
106
119
115
122
131
136
154
153
161
18 0
160
17218 6
194
216
L5
353
457
538
605
665
719
768
8 14
8 57
8 98
975
1045
1110
1171
1229
1337
1436
148 2
15931693
1793
1885
B5
273
377
458
525
58 5
639
68 8
734
777
8 18
8 95
965
1030
1091
1149
1257
1356
1402
15131616
1713
1805
oD2
253
357
438
505
565
619
668
714
757
798
8 75
945
1010
1071
1129
1237
1336
1415
15121605
1693
178 5
DP
228
302
360
406
450
48 7
521
554
58 5
613
668
717
764
8 06
8 47
924
994
1050
1118118 4
1246
1311
DL
150
150
200
200
200
250
250
250
250
250
250
250
250
250
250
250
250
250
250250
250
250
DM
30
30
40
40
40
50
50
50
50
50
50
50
50
50
50
50
50
50
5050
50
50
DIMENSIONS IN mm
NOTE : The dimensions given in the tables are indicative. Design and dimensions may be modified by CTT without prior notification.
POT bearing type PL
This type of bearing :
- Allows longitudinal and transversal movements
- Does not resist any horizontal load (except friction)
-
8/12/2019 CTT Pot Bearings
8/16
8
POT bearing type PF
This type of bearing :
- Constrains longitudinal and transversal movements
- Bears longi tudinal and transversal horizontal loads
BEARING TYPE
PU-100
PU-200
PU-300
PU-400PU-500
PU-600
PU-700
PU-800
PU-900
PU-1000
PU-1200
PU-1400
PU-1600
PU-1800
PU-2000
PU-2400
PU-2800PU-3000
PU-3500
PU-4000
PU-4500
PU-5000
TH
8 0
8 1
8 5
8 498
96
102
106
119
115
122
131
198
154
153
161
18 0170
192
190
196
216
L5
393
478
538
608665
719
768
8 14
8 57
8 98
975
1045
1110
1171
1229
1337
14361515
1593
1705
1793
1885
B5
293
378
438
508565
719
768
8 14
8 57
8 98
975
1045
1110
1171
1229
1337
14361515
1593
1705
1793
1885
oD2
293
378
438
508565
619
668
714
757
798
8 75
945
1010
1071
1129
1237
13361415
1493
1605
1693
178 5
DP
256
316
360
408450
501
536
568
599
628
68 2
732
778
8 21
8 62
938
10081064
1120
1199
1260
1325
DL
200
200
200
250250
300
300
300
300
300
350
350
350
350
350
350
350350
350
350
350
350
DM
40
40
40
5050
60
60
60
60
60
70
70
70
70
70
70
7070
70
70
70
70
DIMENSIONS IN mm
NOTE : The dimensions given in the tables are indicative. Design and dimensions may be modified by CTT without prior notification.
-
8/12/2019 CTT Pot Bearings
9/16
9
5. Accessories
ANTIDUST SKIRTS
These devices are installed in order to avoid the dust on the sliding parts of the bearing,
that could affect the friction coeficient.
They are recommended either for both free sliding and guided sliding types. They are
manufactured from neoprene strips bolted to the upper plate of the bearing through a
metallic ruler.
Antidust skirts
RULER MEASURING MOVEMENTS
This device is designed to measure then movements of the bearing, and consequently,
the movements of the deck visually.
A metallic or aluminium ruler is connected to the upper plate and a rod is welded, by
means of a support, to the masonry plate or to the pot.
The proj ection of the rod on the ruler indicates the movement of the deck.
Measurement ruler
-
8/12/2019 CTT Pot Bearings
10/16
6. Site Installation
10
2. LEVELLING OFTHE BEARING
Place the pot bearing in its position levelling it with
timber wedges. It is important to ensure that the X
axis of the bearing is aligned in the longitudinal
direction of the bridge and that the X and Y
directions are accurately horizontal. For bearings
allowing horizontal displacements it should be
checked that the arrow painted on the slide plate
is pointing in the correct direction.
1. PREPARATION OF THE PIERS
Build the piers leaving on them the required
recesses according to the dimensions indicated
on the drawings.
3. GROUTlNG
Install the form for grouting the space between
pier and pot bearing. Grout the space between
pier and pot bearing. Fill in the recesses checking
that the level is the correct.
5. REMOVAL OF FIXING PLATES
Once the formwork has been removed, thebearing is definitively installed. Remove the lateral
fixing plates of the bearing in order to allow its
free movement.
4. FORMING OF DECK
The formwork of the deck is placed embedding
the upper dowels of the bearing.
-
8/12/2019 CTT Pot Bearings
11/16
11
7. POT bearings for incrementally launched bridges
POT bearings for incrementally launched bridges have a
dual function. First, they provide low friction sliding surfaces
over piers as the deck is launched during construction.
Thereafter, they become permanent bearings for the
completed bridge. A POT bearing serving both functions is
shown in the picture above.
During construction, a fixing device avoids relative
movement between sliding plate and pot cylinder.
POT bearing for ILM bridge
The sliding plate is supplied with a second stainless
steel sheet on top. Inserting neoprene-teflon pads
between deck and bearings allows the launching
operation to be carried out. Pads, second stainless steel
sheet and fixing device are removed after launching. To
achieve this, the deck is lifted by means of hydraulic j acks
placed on top of the piers.
Once this operation is achieved, the deck is lowered to
its final position, the j acks are removed and the sliding
plate is connected to a previously embedded steel platein the deck.
Finally, the fixing devices used for transportation are
released, thus the bearing is in its final service position.
For the correct design of these bearings, it is very
important to know the loads during launching, because,
they have maj or influence in the actual length and
thickness of the sliding plates.
Although the cost of this type of bearing is higher than
the standard ones, their use represents a saving for the
j ob because :
- Temporary launching bearings are not required
- Demolition and replacement of the temporary bearings
by permanent ones, are costly and time consuming
are avoided.
-
8/12/2019 CTT Pot Bearings
12/16
8. Special POT bearings
12
DOUBLE POT BEARINGS
Bearings with double pot and single upper plate.
They are designed for an ILM bridge. The aim was
to center the loads during launching under the webs
of the concrete deck.
These bearings were installed in the High speed
railway Madrid-Sevilla at Ademuz (Cordoba).
BEARINGS WITH "SPRINGS"
These bearings incorporate external springs that
control the relative movements between sliding
plate and pot.
These bearings were installed in the Cartuj a
viaduct in Seville (approaches to Alamillo bridge).
ELIPTIC POT BEARINGS
The pot has an elliptical shape. These bearings werespecially designed for the Aruca-Las Palmas j unction
in the Canary islands.
CTT manufactures special tailor-made POT bearings
designed to fit the technical specifications and requirements
of individual proj ects.
CTT offers a wide range of technical solutions for the design
of special POT bearings; our technical department has the
capability to develop alternatives to the standard product,
thus adapting our design to the proj ect requirement.
The pictures below show several special bearings
designed for specific j obs.
-
8/12/2019 CTT Pot Bearings
13/16
13
9. Recent bridge structures
4TH BRIDGE OVER GUADIANA RIVER
IN BADAJOZ. SPAIN
OWNER:
J unta de Extremadura.
CONTRACTOR:
UTE Puente de Badaj oz
DYCSA-FCC
CONSULTANTS:
FCC Construccion. Servicio Tecnico.
D. J os Ignacio Gonzalez Esteban,
D J os Luis Alvarez Poyatos
BEARING TYPE:
PL-1000, PL-500, PU-1000, PU-500
VIADUCT OVER GOR RIVER IN
GRANADA. SPAIN
OWNER
Direccion general de carreteras
J unta de Andalucia
CONTRACTOR:Entrecanales y Tavora
CONSULTANTS:
Direccion general de carreteras
BEARING TYPE:
PL-350, PUE-1150, PLE-1100
BRIDGE OVER VAROSA RIVER
LANCO REGUA-RECONCOS
PORTUGAL
OWNER
J AE
CONTRACTOR:
ENGIL - Soares da Cosat
CONSULTANTS:
Ing. Armando Rito
BEARING TYPE:
PL-38 0, PU-1550,S PU-1450
-
8/12/2019 CTT Pot Bearings
14/16
14
ACCESS TO ALAMILLO BRIDGE IN
SEVILLE. SPAIN
OWNER:
J unta de Andalucia
CONTRACTOR:
U.T.E. Alamillo
DYCSA-FCC
CONSULTANTS:
FCC
BEARING TYPE:
PL-38 0, PU-1550, PU-1450
MADRID-SEVILLE HIGH SPEED
TRAININ ADEMUZ (CORDOBA).
SPAIN
OWNER:
M.T.T.C.
CONTRACTOR:
DYCSA
Entrecanales y Tavora, s.a.
COMSA
CONSULTANTS:
EPTISA
BEARING TYPE:
PL-400, PPUE-1650, PPLE-1650
LAHORE-ISLAMABAD MTY.
PAKISTAN
OWNER:
National Hghway Authority Pakistan
CONTRACTOR:
DAEWOO Corporation (Korea)
MTY CONSULTANTS:
SMEC (Australia)
ILM BRIDGES CONSULTANTS:
CTT-Stronghold (Spain)
Mr. Wolfgang Buchler (Switzerland)
BEARING TYPE:
PL-1000, PUE-1600, PLE-1000
-
8/12/2019 CTT Pot Bearings
15/16
15
10. Quality control and tests
TESTING
The quality and behaviour of CTT POT bearings is
regularly checked by several tests :
- vertical load tests
- vertical and horizontal load tests
- friction tests
- rotation test
These tests are generally carried out in an official
laboratory next to our factory :
- Laboratori General dAssaigs i lnvestigacions LGAI
in Barcelona.
Testing POT bearings in laboratory
CORROSION PROTECTION
All steel areas in contact with the atmosphere are
protected with the following standard corrosion protection:
- surface conditioning by sand blasting according to
SIS-055900, grade Sa 2 1/2
,
- two layers of epoxy primer (cathodic protection),- one finishing layer of acrylic resin and chloride
plasticizer paint.
The minimum total thickness of the three-layer protection
is between 100 n and 120 n.
POT bearings are supplied with different corrosion
protection following specific requirements such as
metalisation or use of special self-protected steels.
High precision techniques are used in the manufacturing
and finishing of POT bearings. Given the loads to be
transmitted and the deformations to be absorbed, the
quality of the materials and workmanship are ensured
by Quality Control Plans regularly revised to meet any
particular specification.
Since early 1997, we have established a quality manual
and a manual of procedures in order to be certified ISO-
9002-94.
CTT, acting as a member of the European Standarisation
Commitee CEN collaborates in the European Standard
for POTbearings.
Testing platform general view
Quality control document
-
8/12/2019 CTT Pot Bearings
16/16