Tools · Elastomeric bearing pad

Elastomeric bearing — first sizing

First sizing of a steel-reinforced elastomeric bearing to AASHTO LRFD Method A (§14.7.6). Give the vertical service load and the shear movement — the same movement the Expansion-joint tool computes — and the tool proposes a pad, or checks one you set yourself. Service-level planning aid; rotation, anchorage and low-temperature grade belong to detailed design.

TheBridgeEng

Elastomeric bearing — first sizing

Elastomeric bearing pad

Design code

The tool finds the smallest pad (50 mm steps) that passes every Method A check.

Bearing section — to scale Shear deformation Δs

Proposed pad — plan L × W

—

Compressive stress—

σs vs min(1.25GS, 8.62 MPa)

Movement demand—

2Δs vs elastomer h_rt

Stability H / (min(L,W)/3)—

total height vs stability limit

Vertical service load1000kN

20026005000

Total service (DL+LL) reaction on one bearing.

Shear movement Δs30mm

060120

One-way movement at this bearing — take it from the Expansion-joint tool.

Elastomer hardness

G_min in MPa (AASHTO). 70 duro is used for sliding bearings, not laminated pads.

Internal layer thickness

Covers = half the internal layer; 3 mm steel shims between layers.

Your trial pad

Length L (longit.)300mm

1506751200

Width W (transv.)450mm

1506751200

Internal layers n4ea

2916

Check (Method A)	Value	Limit	Status

Eurocode and KDS

With Eurocode selected the pad is checked to EN 1337-3 instead of a stress limit. The load and movement sliders become ULS design values F_z,d and v_x,d, and the checks are strain based: compression, shear and rotation strains add up to a total that must stay below 7 (K_L = 1.0, γ_m = 1.0, both recommended values). The shear strain on its own is limited to 1.0, which needs less rubber than the AASHTO rule of twice the movement, but on a larger ULS movement. The tool also checks the steel plate thickness, the rotation limit from the compressive deflection and buckling, with G = 0.9 MPa by default. Slip of a non-anchored pad needs the minimum vertical load and is left to detailed design. KDS 24 90 11 uses the same strain-based method for steel-reinforced elastomeric bearings, with limits written for both limit states: total strain 7 and shear strain 1.0 at the ultimate limit state, 5 and 0.7 at the serviceability limit state, no material factor, and K_L = 1.5 where the strains come from vehicle live load. Pick the limit state of the values you enter.

Field notes — what to watch for

Plan area comes from stress, but thickness comes from movement — the elastomer absorbs translation by shear, and total rubber thickness must be roughly twice the movement. A pad that passes compression and fails rotation lifts at one edge and walks; check both. Anchor the pad detailing to the maintenance question: can it be jacked and replaced?

Inputs are saved on this device · reset to defaults