Deformation supports are elastomeric supports. Upon request, they may be equipped with containment structures.
The specific material characteristics of the elastomer allow rotation and translation to a certain degree by deformation. Due to this material feature, expensive stainless steel sliding panels in combination with PTFE are often unnecessary, which is a great advantage compared to other types of support. The design can be changed to a sliding deformation support (see page 36) if the permissible movement of the elastomeric support itself is not sufficient for the actual application.
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Another positive aspect is that it is an easy-to-maintain type of support. Without the sliding components, it does not even require maintenance. In contrast to other types of support, the component that takes up the vertical load is clearly visible for inspection. Elastomeric supports have been used successfully for decades and have proven their durability. However, if there is a need to replace a support, this is done by lifting the superstructure. Our mounts are designed to allow replacement of the elastomeric support or wear parts by lifting the 10 mm superstructure.
Each deformation support is manufactured individually on a case-by-case basis. In general, a range of different sizes and layered compositions are suitable for the proposed tasks. As a result, we can design the design of each very flexible support structure in accordance with specific requirements.
The cured elastomeric supports are made of a special rubber compound and are equipped with an armed steel sheet during the manufacturing process, so-called vulcanization. Steel sheets provide the required rigidity. Enhanced elastomeric supports are distinguished by low maintenance and durability. In addition, some types can be used under certain conditions without additional steel (limiting) structure.
The elastomeric portion of the support is elastically deformable. Deformation in vertical direction (deflection) under permanent load is calculable and remains constant. The influences of the dynamic loads are generally small and the additional temporary deflections caused by the dynamic loads are small and will not cause problems for most structures.
There are different types of reinforced elastomeric supports. Various types are defined in EN 1337-3. The most common types are described below.
Types of elastomeric supports
Type B (1) – a reinforced support, fully covered with elastomer and containing at least two reinforced steel plates. Permanent load must be sufficient to prevent slippage.
Type B/C (1/2) – reinforced support with an external steel plate on one of the surfaces. The steel sheet allows the use of any methods to protect the slip. Such as dowels, threaded rods, screws, etc. The only slippage protection on one side allows easy installation and replacement. Slip protection is required in case of a pressure lower than the minimum support pressure. The B / C type can be installed if the construction is secured in its position, for example, by a support that is fixed in all directions or transversely. This type of support has always been used in German railway bridges, regardless of the actual load situation.
An additional application for this type of support is the use as anchored buffer eg for buildings.
Type C (2) – reinforced support, both surfaces of the support are made of steel plates to protect against slipping. Replacing supports of this type is difficult to do without additional measures. As a floating support, this type may, depending on the rigidity, transfer horizontal loads (breaks, etc.). An example of replacement C-type support (2) is shown below.
Type C (5) – reinforced support, both surfaces of the support are protected against slipping of profiled steel plates. (eg grooves, slip resistant steel plates). However, due to the fact that the required tasks can not be precisely defined, it should be used only for structures with minor loads or for building construction. Because of the profiled surfaces it can not be equipped with limiting structures.
Note on slip prevention
The choice of a B (1) elastomeric support according to the pre-dimensioning tables requires a minimum pressure of 3 N / mm2 or 5 N / mm, relative to the deployed area of the support.
Standards and regulations do not specify when a single-sided or two-sided support should be used. We recommend a minimum pressure of 1 N / mm2 for the use of a type C support (5). The deviation requirements of the German Railway Authority must be taken into account.
Elastomeric supports made of chloroprene rubber are slightly flammable. The fire extinguishes itself after the flame has been extinguished.
Note on the preliminary design
The analysis of the elastomeric supports for the proposed application according to EN 1337-3 differs from the basic requirements of the old DIN 4141, where maximum loading, displacement and rotation values can be used. Due to the complexity, the number of requirements and the missing design values for different tasks, it is no longer possible to provide the designer with correct, well-known tables.
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However, the catalog includes hardened elastomeric support tables that are standardized by GUMBA. Pre-sizing tables allow an estimate of the size of the support. The data presented are characteristic values for service limit status (SLS). For a more detailed analysis we offer a program on our website www.hidroplasto.com, with instructions for use being included. It allows for a design support idea because the program uses a range of over 3,000 supports. Selection includes standard GUMBA holders (according to DIN 4141), as well as standard sizes according to EN 1337-3.
Compared with the analysis according to EN 1337-3, the data in the table (pages 18-23) for support with the dimensions 300 x 400 mm gives a fairly similar result in the absence of large rotations. For smaller supports the limits according to EN 1337 – can be exceeded at a combination of maximum values for vertical displacement and loading, while retaining capacities for larger sizes.