Catalogs >
Mageba >
LASTO® – Elastomeric bearings

LASTO® – Elastomeric bearings
8Pages

Catalog excerpts

LASTO® – Elastomeric bearings Unreinforced deformation bearings

Function • Transmission of vertical loads and accommodation of horizontal movements and rotations Permissible pressure • < 20 N/mm2 (at service level) Shape and dimensions • Any, up to 1.20 x 1.20m Bearing type • Deformation bearing, unreinforced Materials • Natural rubber (NR) • Chloroprene rubber (CR) CR: 74 ± 5 IRHD • Thermal conductivity 0.26W/m ■ K • Ozone resistance Level 0 Performance under permanent loading Elastomers deform under permanent loading, even without increasing load. This so-called creep deformation continues for somewhat more than 100 days. The...

Open the catalog to page 2

Bearing design Design approaches A - Simplified procedure Conditions for use • Rectangular bearing without holes • Only subjected to vertical loading Step 1 - Decide on preferred dimensions and calculate the average pressure Step 2 - Check the permissible pressure from Table 1 Step 3 - Check the edge clearance according to Figure 2 B - Procedure for all other cases (Formulae: see pages 4 und 5): Comments • Vertical bearing deformation should not exceed the maximum permissible compression strain £z < 30% • Rotation or shear deformation of the bearing may arise • Other bearing shapes or...

Open the catalog to page 3

Design concepts Basic concepts The impact of bearing geometry is considered by the shape factor, S. This is defined as the ratio between the area of the loaded surface and the sum of the areas of the freely deformable sides. Side surfaces which cannot deform freely due to adjacent structural elements (e.g. the side of a bolt hole with little clearance to the bolt) are not considered. Vertical deformation Shape factor Rotation angle The bearing design ensures that the deformed bearing retains adequate thickness trest to prevent a collision between structural elements. The minimum remaining...

Open the catalog to page 4

Design concepts Check of sliding resistance The coefficient of friction μ is calculated as follows: μ = 0.1 + with Kf = 0.6 for concrete and Kf = 0.2 for all other surfaces. The horizontal restoring force Fx and the check of sliding resistance results from: where vx,y is the total horizontal deformation (vector addition), A is the footprint area and the shear modulus G = 2.2 N/mm2. The permissible horizontal deformation is thus: Remaining thickness trest [%] The horizontal movement of the supported structural element must be limited in order to prevent sliding and displacement of the...

Open the catalog to page 5

Design tables Table 1: Maximum permissible pressure a [N/mm2] Maximum permissible pressure in N/mm2 for a minimum remaining thickness of 70 % of the nominal thickness, depending on side lengths a, b and thickness t. For example, a bearing of dimensions 80 x 200 x 10 mm3 will be compressed to a thickness of 7 mm under a pressure of 12.9 N/mm2. Values for Example A on Page 5 vxy Table 2: Maximum permissible shear strain £„,y = —f- [mm] Maximum permissible shear strain, exy = vxy /t, of a bearing to its full capacity. For example, a bearing of dimensions 80 the bearing is loaded with full...

Open the catalog to page 6

Product range and installation guidelines Product range Delivery form Full slabs or cut to size according to clients' wishes Thicknesses of up to 20 mm are available from stock, other thicknesses on request Installation guidelines LASTO®BLOCK F bearings are generally laid on a smooth flat surface without ridges, burrs or large recesses. When laid on concrete or a mortar bed, it must be ensured that the surface has adequate strength. It must also be ensured that the bearing surfaces are clean and grease-free.

Open the catalog to page 7

Tender texts for bearings of natural rubber (NR) Supply and installation of high-capacity, unreinforced deformation bearings of natural rubber (NR) Product: LASTO®BLOCK F The permissible loading depends on the bearing geometry and is limited to max. 20 N/mm2. Proven remaining bearing thickness under a permanent load of duration 100 days to be min. 70% of nominal thickness. Required displacement capacity vxy = ...mm Required rotation capacity a = ... %o Bearing thickness: ... mm Dimensions (L x W) : ... mm x ... mm Including creation of a flat load-bearing surface. Units:...

Open the catalog to page 8