Concentrically Braced Frame Design

2D CBF design per IS 18168:2023 · IS 800:2007 · IS 1893:2016

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Phase 7 — end-to-end CBF designer with report: IS 1893 lateral load → 2D stiffness across 5 combos → IS 800 brace design → IS 18168 Cl. 12.2.2.2 capacity envelope (global + pre-buckle + post-buckle) → IS 800 beam & column checks → Roeder-Lehman gusset plate connection → SVG diagrams (frame + AFD + BMD + SFD) → downloadable ReportLab PDF report with every intermediate value and clause reference.

Geometry

Configuration

No. of storeys

Span L (m)

Storey height h (m)

Materials (Brace / Beam / Column)

fy (MPa)

fu (MPa)

Ry (overstrength)

γmo

Loads

Dead load DL (kN/m²)

Live load LL (kN/m²)

SIDL (kN/m²)

Tributary width (m)

Ω (CBF)

Base shear override (kN, blank = auto)

Seismic (IS 1893:2016)

Zone

Soil

Importance factor I

R (CBF)

Ta formula (Cl. 7.6.2)

Sa/g method ("Formula" = IS 1893 Fig 2; "Peak flat" = 2.5, matches ETabs auto default)

Lateral forces override (kN, comma-separated per storey; blank = auto)

Preliminary Sections

Brace (CHS per IS 1161:2014)

Beam (IS 808)

Column (IS 808)

Only show IS 18168:2023 EQ-compliant beam / column / brace / link sections (uncheck to browse the full IS 808:2021 catalog)

Compactness limits recalculate live from your f_y input. Sections failing the criterion appear in amber with a ✗ EQ tag.

Gusset plate & weld (Roeder balanced design)

Gusset fy (MPa)

Gusset fu (MPa)

Weld leg W₂ (mm, ≤ brace t)

FEXX (weld material, MPa)

Nw (# weld lines)

Ry (brace overstrength)

Want a different beam / column / brace at every storey? Open per-storey sections page →