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SDOF blast response

Elastic single-degree-of-freedom response of a structural element to a blast pulse: natural period, dynamic load factor (DLF), and peak deflection.

Civil-protection / accidental-explosion scope only (UFC 3-340-02, public release). Weapon-effects and penetration calculations are out of scope.

Elastic (linear) SDOF by Newmark average-acceleration integration. Elastic response only — no plastic hinge / ductility. Idealize the element as an equivalent mass–spring first (transformation factors are outside this tool).

Inputs

Equivalent mass mkg

Stiffness kN/m

Peak force F0N

Pulse duration tds

Pulse shape

Damping ratio ξ

Results

T_n [s]—

t_d/T_n—

Static deflection x_st [mm]—

DLF—

Max deflection x_max [mm]—

Citations

NEWMARKm·ẍ + c·ẋ + k·x = F(t) integrated by Newmark average-acceleration (β=1/4, γ=1/2). DLF = x_max/(F0/k).

VERIFYIntegrator verified vs analytic rectangular pulse: step→DLF=2.0; td/Tn=0.25→DLF=1.414.

Engine: blast.js v0.1.0 · Method: Newmark β=1/4 · Date:

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Preliminary calculation tool. Results are for preliminary sizing and cross-check only. Final design, sealed responsibility, and permit submissions require the full official text of the referenced regulations and the review of a licensed engineer.