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1 Introduction

MK4 Elastomeric Bearings are deformable structural components constructed partially or wholly from elastomer.

They are essentially designed to transmit vertical loads and accommodate movements between a bridge and its

supporting structure simultaneously, especially for:

transmission of vertical load;

horizontal displacement in all directions;

rotation of the bearing surfaces about all axes;

accommodation of transition horizontal forces with or without additional fixings.

The bearings comprise a block of vulcanized elastomer that may be reinforced with one or more steel plates.

In addition to any internal reinforcement, bearings may have external steel load plates bonded to the upper or

lower elastomer layers or both.

MK4s Technical Department has engineers with the relevant expertise and experience to assist with the selection of

the appropriate bearing for a given application as well as providing the best solution for the clients specific problems.

Since we recognize the importance of simplicity, clarity and ease of use, we emphasize that we can offer both: the

simple standardized series of products and also highly sophisticated customized solutions for specific problems.

This brochure is intended to provide a quick and expedient reference and guide for designers, engineers and

contractors alike.

2 Standard types

Elastomeric bearings are equipped with several vulcanized steel plates in order that internal lateral contraction will

be prevented. The result is that load carrying capacity increases, resilience is reduced, while lateral displacement

and distortion of the adjacent structural elements can be compensated by the bearing. Reinforced elastomeric

bearings are of simple construction, do not require maintenance and are corrosion proof. They have a long service

life, even under extremely onerous environmental conditions.

Bearings fully covered with ElastomerNon Anchored TypesReinforced elastomeric bearings are designed in accordance with loads to be absorbed and displacement and

distortion movements to be expected. Allowable surface contact pressures must be taken into account, as well

as the resulting bearing reaction forces, movements and installation tolerances:

Contact area Admissible Pressure Nmax Required Pressure Nmin

< 50.000 mm2 10,0 N/mm2 3,0 N/mm2

< 120.000 mm2 12,5 N/mm2 3,0 N/mm2

> 120.000 mm2 15,0 N/mm2 5,0 N/mm2 Table 1

The rubber cover is generally 2,5 mm on top and bottom surfaces and 5-6 mm laterally. The number and thickness

of layers is defined by the required translation and rotation. Therefore they are different for each bearing and are

given in page 6.

Type A: Laminated bearings fully covered with elastomer comprising only one steel reinforcing plate (former Type 1)

Type B: Laminated bearings fully covered with elastomer comprising a minimum of two steel reinforcing plates

(former Type 1)

Type A

Type B

Bearings with outer Steel PlatesAnchored TypesWhenever the minimum surface contact pressures falls below 3 N/mm2 the following bearings should be used.

All these bearings are provided with external steel plates (see page 6).

Bearings with outer steel plates and anchorages

These bearings are especially useful where traction and high horizontal forces are to be transmitted. The anchoring

of these bearings is effected by dowels or bolts.

Type C(1): Laminated bearings with outer steel plates and bolts (former Type 2a).

Especially for use with cast-in-situ beams with occasional, temporary and irregular traction forces. These bearings

are non-replaceable.

Type C(2): Laminated bearings with outer steel plates, anchor-plates and dowels (former Type 2b).

Especially for use with steel beams with occasional, temporary and irregular traction forces. These bearings are

replaceable.

Type C(3): Laminated bearings with outer steel plates, anchor-plates and shear-keys (former Type 4).

These bearings are especially useful in case of large movements but small loads. They are replaceable.

Bearings with profiled outer steel plates

Type C(4): Laminated bearings with profiled outer steel plates (former Type 5).

These bearings can be utilized on a variety of structures. The anchoring is effected by increased friction between

substructure and bearing by the dowel-like action of the vulcanized bonded chequered or channelled plates on

the mortar bed. They are designed for both cast-in-situ concrete and precast concrete elements.

These bearings are non-replaceable.

Type C (1)

Type C (2)

Type C (3)

Non-standard types

Low-Friction Sliding BearingsSince the deformation capacity relates to the geometrical form of the bearings, there is the facility to allow for

larger movements by adding a sliding surface in combination with a PTFE surface and stainless steel. MK4 sliding

bearings consist of a reinforced elastomeric bearing with a sliding system, including optional horizontal force

absorption. Also here the combination of all available basic types is possible.

Type D: Type B with PTFE sheet bonded to the elastomer.

Type E: Type C with one outer plate bonded to the elastomer and PTFE sheet recessed in the steel.

Plain Pad Bearings and Strip Bearings Non-reinforced elastomeric bearings also absorb displacements and distortions, but only to a limited extent due

to their reduced thickness and size, compared with reinforced elastomeric bearings. They are especially useful for

loads upto 100-150 kN.

These bearings can be produced in any desired size upto 1000 mm in length.

Type F: Plain pad bearings and strip bearings.

Guided Elastomeric Bearings Combined vertical loads and horizontal forces can be transferred with side restraints. For major horizontal forced,

as they occur in large bridge spans, it is more appropriate to use horizontal guided bearings. They transfer these

horizontal forces independently into the substructure.

Horizontal guided bearings transfer loads in both longitudinal and transverse directions.

Type G: Guided Elastomeric Bearings.

4

Type D

Type E

Type G

Type F

Type H

High Rotation BearingsIn the case of large rotations, all the above basic types can be manufactured with alternate internal steel-plates

reduced in plan size so as to offer less resistance to rotations.

The thickness of the elastomeric layers and of the steel-plates is identical to the standard bearing types.

Type H: High rotation bearings.

ILM Bearing PadsIncremental launching for bridges combines the advantage of on-site concreting with prefabricated elements.

MK4s special launching pads are for use with the incremental launching method of construction and other

techniques of sliding bridges. They can be supplied in various formats.

Type I: ILM Bearing Pads

Special BearingsMK4s Technical Department is also well equipped and willing to provide customized solutions to specific

problems. Type I

Up-lift bearing

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C(4)

V a*b; D n W d T W d d d T

MN - mm mm mm mm mm mm mm mm rad/ 1000

A, B

Anchorages forTypes C(2), C(3)

C(1), C(2), C(3)

Total Heightexcl. anchor

plates

Total Heightincl. anchor

plates Total Height

Effectiveelastomerthickness

NON-ANCHORED TYPES ANCHORED TYPES

Admissible load Dimension No. of layers Admissible

displacement +/- Height

Effectiveelastomerthickness

Admissibledisplacement +/-

Admissble rotation

1,93,0

23313946546065697275

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350x4502,4

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mm

1 14 102 21 153 28 204 35 255 42 306 - -

0,100,15 100x100

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B C(4)

V a*b; D n W d T W d d d T

MN mm - mm mm mm mm mm mm mm mm rad/ 1000

Effectiveelastomerthickness

C(1), C(2), C(3)

Total Heightexcl. anchor

plates

Total Heightincl. anchor

plates Total Height

NON-ANCHORED TYPES ANCHORED TYPES

Admissible load Dimension No. of layers Admissible

displacement +/- Total Height

Effectiveelastomerthickness

Admissibledisplacement +/-

Admissble rotationAnchorages forTypes C(2), C(3)

500 550

500x600

2,93,64,5

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600 650

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700x800

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800x800

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Quality Control

MK4 and all their sub-suppliers are subject to a strict quality-control system as a part of the ISO 9001/EN 29002

certification.

The quality of the MK4 bearing production is continuously monitored by independent testing laboratories and

internal quality control complies with established international standards.

Quality control procedures and other verifications are applied throughout the production phase for:

materials;

workmanship;

finished product;

to ensure that the components satisfy the relevant standards.

If required, load tests on finished bearings can be performed both in-house and externally at official testing

laboratories.

Furthermore, all elastomeric bearings can be, if required, manufactured under the control of Technical University

Munich and are entitled to display TUM-sticker or under French standards (NF-sticker).

In addition, MK4 engineers are available to provide technical advice relative to quality standards of the interfaces,

bearing installation, cement joint forming, bearing plinth design, etc. .

8

Installation

Professional installation is the unconditional prerequisite for optimum use and service life of the bearings.

Elastomeric bearings are sensitive to rough handling during construction operations. They should therefore be

treated carefully during transportation, assembly and installation.

Handling and installation of bearings should only be carried out by qualified personnel whose knowledge and

experience are well proven.

Generally bearings should be installed horizontally on an intermediate bed of mortar which serves as a levelling

course.

It must be taken into account that, due to its type of deformation, elastomeric material will not be suitable if it is

restrained laterally.

Care should be taken to keep the bearing clean and protected to avoid damage by grout or concrete and to

ensure that it can be replaced without difficulty if required. Suitable preventative measures should also be taken to

ensure that the bearings do not come into contact with grease, solvents or similar materials.

If required, MK4 can submit a technical manual which contains a detailed description of the installation process.

9

BARCELONA

Can Pantiquet, 47- 308100 Mollet del Valls

Tel. + 34 90 215 35 33Fax + 34 93 570 60 03

mk4@mekano4.com

MADRID

Sector Esculturas, 5 Local28760 Tres Cantos

Tel. + 34 91 804 92 60Fax + 34 91 803 28 64

mk4_mdr@mekano4.com

MeKano4, S.A.

www.mekano4.com