Elastomeric bearings reinforced internally with one or more steel plates, chemically bonded during vulcanisation are called laminatid elastomeric bearings.
Elastomeric bearings permit a smooth and uniform transfer of loads from beams to substructure and also allow beam rotations at the point of support due to deflection of beam under loading.
They further allow lateral and longitudinal movement of beams caused by thermal forces.
Elastomeric bearings have no moving parts and thermal expansion and contractions are supported by shear capacity of elastomers.
There is no sliding motion between bearing and beam or between bearing and abutment.
The bearings we have defined so far are the basic types, which constant feature is the fact that they allow all-ways movements and rotation.
However, movements can be limited in one or all ways, thus obtaining guided or fixed bearings, respectively. In the first case -guided bearings- the restriction is obtained by means of guides parallel to the supporting axe that allows movement.
To make friction as low as possible, PTFE and stainless steel sheets are welded to the guides.
If, on the contrary, a fixed bearing is desired, guides are added parallel to both axes, so that movement is completely blocked.
Each elemental layer, subject to stresses and movements, deflects
Elastomeric bearings we have defined so far are the basic types, which constant feature is the fact that they allow all-ways movements and rotation.
However, movements can be limited in one or all ways, thus obtaining guided or fixed bearings, respectively.
In the first case -guided bearings- the restriction is obtained by means of guides parallel to the supporting axe that allows movement.
To make friction as low as possible, PTFE and stainless steel sheets are welded to the guides.
High damping rubber bearing (HDRB) were developed in 1985 by Professor James Kelly at the University of California at Berkeley.
Ozdekan was the first company which manufactured and applied this technology in Turkey, using it in 2014 for the AFAD building in Ankara, Turkey.
The isolating system was designed with consultation by engineers.
Ozdekan was the first company in Turkey which developed the lead rubber bearings with consultation of university researchers.
The HDRB isolators are composed of a series of vulcanized rubber layers separated by reinforcing steel plates, thus providing a device capable of supporting high vertical loads with minimal compression (elevated vertical stiffness) and allowing high horizontal displacements with relatively small reactions (low horizontal stiffness).
The main property of the rubber is its ability to dissipate energy (damping capacity). When positioned underneath a building or bridge beams, they have the effect of increasing the structure's fundamental vibration period, thus greatly reducing any effects of seismic activity.
The HDRB isolators are bolted to external metal plates allowing them to be fixed to the adjacent structures using anchor brackets or bolts.
The behavior of the LDRB isolators is highly linear in shear stiffness and the damping ratio is 2 - 3% of critical damping.
There is no creep in the material and the stability of the modulus of elasticity is very good.
Advantages of LRDB insulators; they can be modulated in a simpleway and they are less affected by the factors that have mechanical behaviors.
These insulators may need additional damping elements.
These isolators are similar to the previous but with the exception that the dissipation of energy is obtained also through the use of one or more lead cores.
Lead (used here at a level of gg.go% purity) has the property of undergoing plastic deformation as it dissipate energy and then re-crystallizing after a cycle of plastic deformation.
Because of this, it is able to sustain an unlimited number of hysteresis loops.
Elastomeric bearings consisting of a solid block of vulcanised elastomer without internal cavities are called plain pads.
Plain pads are economical efficient support for precast and pre-stressed concrete or steel beams in bridges and buildings.
These pads are designed according to required standards and shear modulus of the manufactured elastomer may vary between 0.6-1.35 MPa to meet the customers need.
The Ozdekan EXpansion Joints are waterproof expansion joints that allow absorption of the deck movements. These joints are manufactured with rubber elements and restrained to the structure with proper anchor bolts.
The reinforcing metal profiles made of steel are completely inserted and vulcanized to the rubber. This process is a total guarantee against corrosion and allows a longer life to the product.
The rubber compound, too, has been intentionally formulated to resist the oil, grease, petrol, salt and sand, without besides, suffering premature ageing phenomena due to sun rays, salt and snow.
All the joints follow the deformations and movements of the structure (the movement can exist with every skew angle from 0° to 90°) by shear deformation of the rubber elements.
Anchor bolts, made of steel and protected with anticorrosion treatments, absorb the elastic reactions and all the other kind of mechanical solicitations.
The joints are also able to compensate height difference or vertical movements. This characteristic is very important in all the cases where load and movement conditions can cause relative vertical movements. The joint series is manufactured by Ozdekan since 2006.
Main advantages:
Simple and linear design with few elements
Low height of the profile
Total impermeable
Easy assembling eitheron concrete structure
Suitable for the replacement of existing joint
Easy and quick to be replaced
Good resistance to vehicles sliding
Vertical movements absorption
The joints are supplied in variable length elements depending to the joint type. A joint line consists in fact of many units joined together with a groove-and-tongue junction welded with special glue. The joint fixing is obtained by chemical anchors; the nuts are locked using a dynamometric key so that permanent compression strength is given to the joint. Stainless steel anchors may be provided on request. In that way the horizontal forces, due to breaking of vehicles and to the reaction that rubber opposes to the joint deformations (shrinkage, creep, thermal variations etc.), are transmitted by friction between the rubber and the concrete. The joints can be assembled on a metallic infrastructure. The joints of bigger movements with four upper grooves are manufactured in order to prevent the lifting of the elements during the contraction. These devices guarantee the adhesion of the elements to the structure and the noiseless of the traffic.
