Falsework Load Calculator

Formula used

• Concrete dead load: q_c = γ_c × t, where t is slab thickness (m) and γ_c is unit weight (kN/m³).
• Dead load total: D = q_c + q_form + q_beam + q_sur.
• Equipment spread load: q_eq = P / A (quick uniform check).
• Impact-adjusted live load: L = (q_live + q_eq) × (1 + I), where I is impact as a decimal.
• Uneven distribution: q_svc = (D + L) × (1 + U).
• Factored design: q_des = (φ_D D + φ_L L) × (1 + U).
• ASD design: q_des = q_svc × SF.
• Totals: W = q × A (kN), and W/post = W / N.

How to use this calculator

1. Enter the supported area that the falsework system carries.
2. Add slab thickness and a suitable concrete unit weight.
3. Include formwork and beam/joist dead load allowances.
4. Set construction live load and any equipment point load.
5. Adjust impact and uneven factors for placement conditions.
6. Enter the number of posts and their allowable capacity.
7. Select a design method and confirm the factors used.
8. Press Calculate to view service and design loads above.
9. Use per-post results to check the shoring layout quickly.
10. Download CSV/PDF to attach to permits and inspections.

Example data table

Load components to capture

Falsework demand starts with wet concrete self-weight, governed by unit weight and slab thickness. Add formwork sheathing, stringers, walers, and joist allowances, plus any planned overpour or ponding surcharge. Construction live load should represent workers, tools, rebar carts, and placement tasks during the active pour period. For elevated decks, include beam cages, embedded items, and temporary platforms if they sit on the same system.

Impact and staging adjustments

Pumping, chute movement, and mechanical vibration can amplify temporary live effects. The impact factor increases live and equipment components to reflect these dynamic actions. The uneven distribution factor accounts for partial pours, stockpiling bundles, and crew clustering. Use conservative percentages when access routes concentrate loads on limited bays or when placement advances in strips.

From area pressures to total force

The calculator treats pressures in kPa as kN per square meter and converts them to total force by multiplying by supported area. Equipment entered as a point load is spread over area for a quick uniform check. This helps screening, but localized checks remain important where wheels, outriggers, or pump legs create small contact areas.

Per-post demand and capacity checks

Total service and design forces are divided by the number of posts to estimate average demand per prop. Compare this demand to the allowable post capacity to flag overstressed layouts. If results approach capacity, reduce bay size, add posts, increase bracing stiffness, limit stored materials, or revise pour sequencing to keep load paths short and stable.

Documented outputs for reviews

CSV and PDF exports summarize inputs, breakdown, totals, and pass or fail checks in formats suited for submittals and site audits. Record pour dates, shoring drawings, and inspection notes alongside each export so assumptions remain traceable. Update the calculation whenever thickness, live activity, equipment, or prop counts change, and verify footing bearing and lateral stability before placement begins. Where the design method uses load factors, choose values aligned with project specifications and any governing temporary works standard applicable.

FAQs

Q1. What is the difference between service and design load?
Service load is the combined dead and live demand before design factors. Design load applies either load factors or a safety factor, giving a conservative target for shoring checks and temporary works review.

Q2. How should I choose the construction live load?
Use the value required by your project specifications. If none is stated, base it on expected worker density, tools, rebar handling, and placement operations, then apply an impact factor when vibration or rapid movement is expected.

Q3. Why is the equipment load spread over area?
It provides a quick uniform screening check using P divided by supported area. For critical equipment, also evaluate localized effects at wheels, outriggers, or pads, because real contact areas can be much smaller.

Q4. What does the uneven distribution factor represent?
It accounts for non-uniform placement such as partial pours, material stockpiles, or staged crew activity. Increasing it raises both service and design totals to reflect load concentration on part of the falsework system.

Q5. How do I reduce per-post demand if checks fail?
Add posts, reduce bay spacing, increase framing stiffness, improve bracing, limit stored materials, or adjust pour sequencing to reduce simultaneous loaded area. Verify footing bearing, base plates, and lateral stability when changing layouts.

Q6. Does this replace an engineered temporary works design?
No. It supports planning and quick checks using transparent assumptions. For complex geometry, tall shores, eccentric loading, wind, or critical pours, follow your temporary works procedure and obtain engineering review as required.

Use project specifications and qualified review for final temporary works decisions.