Seismic Tank Loads Calculator (ACI 350.3-06)
Seismic design loads for rectangular liquid-containing concrete tanks per ACI 350.3-06. The stored liquid is split into impulsive and convective components, and the tool reports design shear and overturning moments per metre width of wall with the full hand calculation. A plot shows the dynamic pressure over the wall height for exterior and dividing walls.
ACI 350.3-06By Arun Kishore, P.Eng. Updated
Open calculatoropens in a new tabCode references
- ACI 350.3-06
- Eq. 9-1 and 9-2: impulsive and convective liquid weights
- Eq. 9-6 to 9-8: effective heights including base pressure
- Eq. 9-32, 9-37 and 9-38: impulsive and convective spectral accelerations
- Eq. 9-34: effective mass coefficient
Inputs and outputs
| Inputs | Include dynamic properties of exterior soil (optional) |
|---|---|
| Inside length parallel to the earthquake, L (m) | |
| Wall height, h_wall, and design liquid depth, h_fluid (m) | |
| Wall, roof and base slab thickness (mm) | |
| Importance factor category | |
| Site class, A to E | |
| Spectral accelerations Ss and S1 (g) | |
| Ratio of vertical to horizontal design acceleration, b | |
| Tank is buried (yes or no) and response modification category, Rw | |
| Roof weight plus superimposed dead load and applicable snow, Wr (kN) | |
| Liquid and concrete densities (kN/m³) | |
| With soil included: dynamic earth and groundwater pressure, its height and soil density | |
| Outputs | Impulsive and convective liquid weights |
| Convective period and design spectral accelerations | |
| Dynamic lateral forces from walls, roof, impulsive and convective liquid | |
| Fluid design shear and total design shear at top of foundation | |
| Total overturning moment at base of tank and at top of footing | |
| Dynamic pressure plot over the wall height, exterior or dividing wall, with an equivalent trapezoidal distribution |
Worked example
Worked example coming soon.
Limitations and assumptions
- Rectangular tanks only. Forces are per 1 m width of wall.
- The convective response modification factor is fixed at Rwc = 1.0.
- Site coefficients Fa and Fv come from built-in step tables and are not interpolated.
These calculators are aids, not a substitute for engineering judgment. Check results independently and against the governing code edition before relying on them.