Blast Load SDOF Calculator (UFC 3-340-02)
Single-degree-of-freedom (SDOF) response of a structural element to a blast pulse. You enter the element's mass, stiffness, resistance and tributary area with the peak pressure and positive phase duration from the design criteria, and the tool steps through time to report maximum displacement, rebound and dynamic shear. The app cites UFC 3-340-02 and the ASCE guide on blast resistant buildings in petrochemical facilities.
UFC-3-340-02By Arun Kishore, P.Eng. Updated
Open calculatoropens in a new tabCode references
- UFC 3-340-02
- ASCE, Design of Blast Resistant Buildings in Petrochemical Facilities
Inputs and outputs
| Inputs | Mass of the element, M (kg) |
|---|---|
| Damping coefficient, c (kN/m/s) | |
| Material resistance, Ru (kN) | |
| Stiffness of the element, k (kN/m) | |
| Static pressure, if any, Ps (kPa) | |
| Peak blast pressure (kPa) | |
| Tributary area of the element, A (m²) | |
| Positive phase duration, Tpf (ms) | |
| Outputs | Whether the element stays elastic, and the time it first yields if not |
| Maximum displacement and maximum rebound displacement (mm) | |
| Maximum dynamic shear (kN) | |
| Force, displacement, dynamic shear and resistance histories as charts and a data table |
Worked example
Worked example coming soon.
Limitations and assumptions
- Peak pressure and phase duration are inputs. The tool does not derive them from charge weight and standoff.
- The blast pulse is triangular, decaying linearly to zero over the positive phase. The negative phase is not modelled.
- Resistance is elastic-perfectly plastic and equal in rebound.
- Load-mass factors (0.78 elastic, 0.66 plastic) and dynamic shear coefficients are fixed. The input help gives simply supported formulas for Ru and k.
- The time step is Tpf/125 and the run covers 10 times Tpf.
These calculators are aids, not a substitute for engineering judgment. Check results independently and against the governing code edition before relying on them.