Design pads confidently for beams and columns. Compare movement, rotation, and material stiffness fast here. See checks, margins, and printable reports in seconds now.
| V (kN) | L (mm) | W (mm) | σallow (MPa) | Δ (mm) | θ (mrad) | γallow | Recommended thickness (mm) |
|---|---|---|---|---|---|---|---|
| 900 | 300 | 250 | 10.0 | 6.0 | 5.0 | 0.70 | ≈ 27–35 |
| 1200 | 350 | 300 | 12.0 | 8.0 | 6.0 | 0.80 | ≈ 28–40 |
| 600 | 250 | 200 | 8.0 | 4.0 | 3.0 | 0.60 | ≈ 20–30 |
Bearings transfer reactions from superstructure to substructure while allowing movements. The calculator starts with vertical load and plan area to compute compressive stress in the pad. Comparing this stress to an allowable limit shows whether the selected footprint is reasonable before thickness sizing. When required area exceeds provided area, increase length or width, reduce load effects, or confirm the allowable stress from the bearing type and project specification.
Elastomeric pads accommodate translation by shear deformation. A target allowable shear strain provides a direct thickness requirement using t ≥ Δ/γallow, where Δ is predicted horizontal movement. Using a strain limit helps screening across rubber grades because it ties performance to deformation. Larger movements, tighter strain limits, or thin pads raise utilization and increase the risk of bulging and serviceability issues.
Support rotation creates differential displacement across the bearing surface. The calculator estimates edge displacement as θ·(L/2) using rotation in radians and the loaded length. That displacement produces additional shear demand, checked as γrot = δedge/t. Translation and rotation act together, so combined strain is the square root of the sum of squares. If rotation governs, increasing length without thickness can raise demand, so detailing decisions should be coordinated.
Selecting multiple rubber layers distributes thickness and affects shape factor, S = LW / [2(L+W)tlayer]. Higher shape factor increases confinement and raises effective compression stiffness. The tool uses an engineering estimate Eeff ≈ 6G(1+2S²) to approximate compressive strain and shortening under load. This helps assess whether vertical deformation suits adjacent supports, grout beds, and leveling tolerances.
Thickness recommendations include a cover allowance on each side for fit-up and durability. Use pass or fail indicators to guide iterations, then validate with governing standards, manufacturer guidance, and long-term effects such as creep, temperature, and aging. Exported CSV and PDF reports capture inputs, utilization ratios, and key intermediate values for design notes, peer review, and construction submittals. Document assumed load combinations, movement sources, and inspection conditions to keep the calculation traceable during revisions.
Use the load level required by your project standard. If allowable stress is specified for service conditions, enter service reactions. If your specification uses factored resistance format, enter factored reactions and matching allowable limits.
Use the value provided by your governing standard, specification, or bearing supplier for the selected pad type and temperature range. Do not assume a generic value if durability, long-term creep, or high confinement requirements apply.
It is a deformation limit that controls how much shear distortion the pad can sustain. Lower limits increase required thickness and usually reduce bulging risk. Higher limits may be acceptable for short-term movements when detailing and material grade support it.
Rotation creates edge displacement across the pad, producing additional shear deformation. If the rotation demand is large relative to thickness, strain can exceed the limit even when translation is small. The combined check captures both effects.
Shape factor reflects how confined each rubber layer is. Higher shape factor generally increases compression stiffness and reduces vertical strain. It can also raise compressive stress sensitivity, so it helps you judge whether layer thickness and plan dimensions are practical.
Always validate before finalizing construction documents. Confirm long-term effects, temperature limits, manufacturing tolerances, and reinforcement details. Use the exported report to communicate assumptions and results during review and submittal.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.