Calculator Inputs
Example Data Table
| Case | Thickness (mm) | Spacing X (m) | Spacing Y (m) | Posts | Design Panel Load (kN) | Load Per Shore (kN) | Adjusted Allowable (kN) | Utilization (%) | Status |
|---|---|---|---|---|---|---|---|---|---|
| Residential slab bay | 150.00 | 1.20 | 1.20 | 1 | 10.61 | 10.61 | 25.50 | 41.62 | Within adjusted allowable limit |
| Heavier slab support | 220.00 | 1.50 | 1.50 | 1 | 23.49 | 23.49 | 34.00 | 69.10 | Within adjusted allowable limit |
| Shared support panel | 180.00 | 1.80 | 1.20 | 2 | 18.20 | 9.10 | 31.50 | 28.88 | Within adjusted allowable limit |
Formula Used
Wet Concrete Load (kPa) = Slab Thickness (m) × Concrete Density (kN/m³)
Service Area Load (kPa) = Wet Concrete Load + Construction Live Load + Formwork Weight
Design Area Load (kPa) = Service Area Load × Impact Factor
Tributary Area (m²) = Spacing X × Spacing Y
Design Panel Load (kN) = Design Area Load × Tributary Area
Load Per Shore (kN) = Design Panel Load ÷ Posts Sharing the Panel Load
Adjusted Allowable Load (kN) = Allowable Shore Load × Reduction Factor
Required Shores = Ceiling of (Design Panel Load ÷ Adjusted Allowable Load)
Utilization (%) = (Load Per Shore ÷ Adjusted Allowable Load) × 100
How to Use This Calculator
- Enter the slab thickness in millimeters.
- Enter the concrete density used for the fresh pour.
- Add temporary live load and formwork weight in kPa.
- Choose an impact factor to reflect placement effects.
- Enter shore spacing in both directions.
- Set how many posts share the panel load.
- Enter the allowable shore load and the reduction factor.
- Click the calculate button to view the result, chart, and export options.
FAQs
1. What does this shoring load calculator estimate?
It estimates wet concrete load, service load, design load, tributary area, panel load, load per shore, required shores, utilization, and remaining capacity using your entered assumptions.
2. Why is tributary area important?
Tributary area controls how much slab area transfers load to one support location. Larger spacing increases tributary area, which raises the load carried by each shore.
3. Why is an impact factor included?
Fresh concrete placement and site activity can increase temporary effects beyond static weight. The impact factor lets you raise service loading to a more cautious design loading.
4. What is the reduction factor used for?
It reduces the listed allowable shore capacity to reflect field conditions, tolerances, connection behavior, or internal company practice. Lower values create a more conservative check.
5. Does this replace an engineer’s design check?
No. It is a planning and screening tool. Final shoring design should consider local code requirements, framing behavior, sequencing, eccentricity, bracing, settlement, and manufacturer data.
6. What units does the calculator assume?
The calculator uses millimeters for slab thickness, meters for spacing, kPa for area loads, and kN for shore reactions and capacities.
7. What does utilization mean?
Utilization compares calculated load per shore with adjusted allowable load. Values above 100 percent indicate the entered arrangement exceeds the reduced capacity used in the check.
8. When should I increase the number of shores?
Increase shores when utilization is high, reserve capacity becomes negative, or required shores exceed the current layout. Reducing spacing also lowers load demand.