LATERAL · DIAPHRAGMS
Diaphragm Opening Analyzer
Model a flexible roof or floor diaphragm with openings: Diekmann sub-diaphragm chord forces & corner straps, collector / drag-strut diagrams from your shear-wall layout, load in either direction, deflection, and capacity checks for wood structural panels (SDPWS-2021), steel deck, and concrete (ACI 318-19) — with every number backed by the step-by-step hand calc.
Diaphragm Opening Analyzer
Plan view
Diagrams vs. distance along span, s — V(s), M(s), chord force envelope F(s), deflection δ(s) value
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Project info
Inputs
Assumptions & limitations
- Flexible-diaphragm idealization: the diaphragm distributes shear to the resisting elements by tributary width, not relative stiffness; in-plane diaphragm rigidity relative to the walls is neglected.
- Simple span between the end shear walls (Line A / Line B) — no continuity or moment transfer is assumed at the supports.
- Openings are analyzed by the Diekmann sub-diaphragm (Vierendeel) method, with an assumed inflection point at the opening-strip center. The reported design chord forces carry the full section moment M(s) plus the local Vierendeel couples — a stated, built-in conservatism, not an equilibrium defect.
- Lateral load reverses in service. Chord, collector/drag, and corner strap forces are reported as magnitudes and must be detailed for both tension and compression (±).
- Deflection (b), the virtual-work model with openings, is an engineering estimate of drift — not a code equation. Deflection (a), the SDPWS 3-term closed form, is the code-recognized no-opening-equivalent baseline.