Steel Structural Design Analyzer
IS 800:2007 Steel Frame Design | Gravity Analysis | Design Checks
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Or define the grid layout manually:
Steel Section Assignment
X Grid Lines (Left to Right)
| Label | Position (m) |
|---|
Y Grid Lines (Bottom to Top)
| Label | Position (m) |
|---|
Column Sections
| Section | Area (mm2) | Depth (mm) | Web Along |
|---|
Column Positions
| X Grid | Y Grid | Storey | Type | Web Along |
|---|
Beam Sections
| Section | Area (mm2) | Depth (mm) |
|---|
Beam Positions
Each beam connects two adjacent column positions. Specify category and connection idealization. End-i = From node, end-j = To node. Mixed-end choices (Pinned at i or Pinned at j) release the moment about the strong axis only at the chosen end — shear and axial still transfer. In the preview SVG, = pinned end and = rigid end.
| From X (i) | From Y (i) | To X (j) | To Y (j) | Storey | Type | Category | Connection |
|---|
Secondary Beams
Connect a point on one primary beam to a point on another. Use Pos A and Pos B (0–1) to set the fractional position along each primary, measured from end-i — 0.5 = midspan, 0.333 = one-third from end-i, etc. The backend adds a node at each picked point, splits the primary into two sub-elements, and inserts the secondary as a full FE element with its own design check.
| Primary A | Pos A (0–1) | Primary B | Pos B (0–1) | Storey | Type | Connection |
|---|
When Pos A = Pos B, slab tributary is automatically redistributed to the secondary (the panel splits cleanly into two rectangular sub-panels). When the positions differ, the secondary is still inserted as an FE element with the correct geometry, but the slab keeps its original tributary on the primaries — adjust manually if a sub-panel yield-line analysis is needed.
Slab Positions
Default: slab on every bay. Mark a bay (or one sub-panel of a bay split by a secondary) as Openspace for corridors, atria, or balconies — the perimeter beams lose that side's tributary and seismic mass shrinks accordingly. Thickness (mm) defaults to the global value (set in Step 3); type a value here to override for that bay only — it feeds the DL self-weight estimate and the slab mass for that bay. Clicking a bay in the preview SVG updates this table in real time and vice versa.
| Bay | Sub-panel | Status | Spanning | Thickness (mm) |
|---|
Bays containing a secondary with Pos A = Pos B show two sub-panel rows — toggle either half independently. Bays without a secondary, or with an asymmetric one, expose a single row. Spanning defaults to Auto (concrete IS 456 rule); set it to One-way X or One-way Y for metal deck.
Shear Walls
Define walls between grid points. L/C/T walls use multiple segments sharing a corner.
| ID | Type | Thick (mm) | From X | From Y | To X | To Y | Stories |
|---|
Building Configuration
Seismic Parameters (IS 1893:2016)
Drives the base shear Vb = (Z/2)(Sa/g)(I/R)·W and the EQX / EQY load cases. Changes here flow into Modal analysis and every seismic combination.
Wind Parameters
Optional. A non-zero pressure activates WINDX / WINDY load cases that join the IS 875 combinations.
Cantilever Projections (m)
Steel Grade
Step 4 — Load Information
Define general (base) area loads here, plus any additional loads — wall UDLs, concentrated forces, applied moments, or absolute slab area-load overrides. Each load is tagged as DL — Wall (partitions, masonry — permanent), DL — SDL (floor finish, MEP, ceilings — permanent), or LL — Live. DL-tagged loads contribute 100% to seismic mass and are factored 1.5 in DL combos; LL-tagged loads get the IS 1893 §7.3 reduction (α=0.25 if LL≤3, 0.50 if LL>3) for seismic and 1.5 in LL combos.
General Loading (kN/m²)
Base dead and live area loads. Self-weight of slab, beams, and columns is computed automatically from section properties and the slab thickness.
Per-bay thickness can be overridden in the Slab Positions table in Step 2.
ⓘ How dead load, live load and seismic weight are estimated
= additional floor DL (this field) + slab self-weightSlab self-weight =
slab thickness × 25 kN/m³ (concrete) for the default; per-bay thickness overrides from Step 2 are honoured. Beam and column self-weights from the section properties are added separately as member loads, so you don't need to lump them into the floor DL.
Roof dead load (DLroof) uses Additional Roof Dead Load + slab SW (same rule).
Live load (LL) is taken as-is. Roof LL and floor LL can differ — typically
1.5 kN/m² for accessible roofs vs 3.0–4.0 for offices / residences (IS 875 Part 2).
Gravity total weight (used as W in displacement checks, design-load envelopes):
Wgrav = Σ (DLi + LLi) × floor_area + Σ beam_SW + Σ col_SW
Sum runs over every storey. Full unfactored LL is included on every floor.
Seismic weight per IS 1893:2016 §7.3 — the live load is reduced:
| Storey | LL ≤ 3 kN/m² | LL > 3 kN/m² |
|---|---|---|
| Non-roof floors | 0.25 × LL | 0.50 × LL |
| Roof | 0 × LL (roof LL excluded from seismic mass) | |
Wseismic = Σ (DLi + αi·LLi) × floor_area + Σ beam_SW + Σ col_SW
Step 5's "Seismic Weight" card shows Wseismic and the α factor used; the "Total Weight" card shows Wgrav. They only coincide when LL = 0.
Additional loads (wall UDLs, point loads, slab overrides defined in the Additional Loading section below) carry one of three tags:
- DL — Wall — partition walls / masonry. Routes to the DL case. 100 % seismic mass (no §7.3 reduction); factored 1.5 in 1.5DL+1.5LL.
- DL — SDL — superimposed dead (finishes, MEP, ceilings, fixed equipment). Same as DL — Wall.
- LL — Live — true imposed / occupancy loads. Routes to LL. §7.3 reduction (α = 0.25 if LL ≤ 3 else 0.50) applies to seismic mass; factored 1.5 in 1.5DL+1.5LL.
Floor Load Assignments (per-slab DL / LL deltas)
Add extra dead or live load on selected slabs (e.g. a library LL on one bay, mechanical room on another). Multiple entries can target the same slab — their loads add. The bay picker opens as a full-page overlay.
| Label | Storeys | Bays | ΔDL (kN/m²) | ΔLL (kN/m²) |
|---|
Additional Loading (wall UDL, point loads, moments, absolute overrides)
Pick a storey range, then click a beam, slab bay, or column on the plan to assign a load. Absolute overrides on a slab REPLACE the tributary load on that bay for the chosen storeys — the warning is shown in the picker. Each load is tagged DL — Wall (partitions, masonry), DL — SDL (finishes, MEP, ceilings), or LL — Live. DL-tagged loads roll into the DL case (100% seismic mass, 1.5 DL factor); LL-tagged loads go to LL (IS 1893 §7.3 reduction, 1.5 LL factor).
The plan picker UI is wired up in the next deploy. For now you can still use the Floor Load Assignments table above for per-slab DL / LL deltas.
| Storeys | Component | Type | Magnitude | Position | Direction | Category |
|---|
Running Basic Gravity Analysis...
Gravity Load Summary
Total Weight = Σ (DL + full LL) × floor_area + Σ beam & column self-weights (used for gravity combinations). Seismic Weight = Σ (DL + α·LL) × floor_area + Σ SW per IS 1893:2016 §7.3 (α = 0.25 if LL ≤ 3, else 0.50; roof LL = 0). See Step 4 → How dead load, live load and seismic weight are estimated for the full derivation.
Running Modal Analysis...
Modal Analysis Results
Running FEM Analysis, This may take 1-5 minutes for large models
FEM Analysis Results
Running analysis...
Running analysis...
Running IS 800:2007 Design Checks...