Foundation Design

Single Column designs or checks pads, sloped pads, strips under walls, plain concrete pads, combined footings under 2–6 columns in a line (two columns: a rectangle or a trapezoid with its centroid under the loads — for the heavier column at a property line), and pile caps on 1–9 piles. Footing Schedule designs a list of columns at once. Site Plan places and designs every footing on a plot.

Open it at /civiltechstudio/foundation-design/app. Status: live.

Design footings for four 400 × 400 mm columns in one run on 150 kN/m² soil, and let the schedule group them into drawing marks.

1. 1Select the Footing Schedule tab.
2. 2In the Design basis bar, choose IS 456, enter SBC 150 kN/m² with the basis net (report), set Founding to 1.5 m, and pick M25 concrete and Fe500 steel.
3. 3Under Column schedule, select Clear, then select Add column three times. The rows are labelled C1 to C4.
4. 4Under Load (kN), enter the service axial loads: C1 500, C2 800, C3 800, C4 1100. These loads are unfactored.
5. 5Open Assumptions and set Col b (mm) and Col d (mm) to 400.
6. 6Select the button under the table, which now reads Design 4 footings.

• IS 456:2000, ACI 318-19 and EN 1992-1-1 (Eurocode 2) — every footing type and mode.
• AS 3600:2018 (with AS/NZS 1170.0) and CSA A23.3-19 (with NBCC 2020) — reinforced pads, sloped pads, strips, combined footings and pile caps, on the Single Column tab only.
• Load combinations per IS 875 / IS 456, ASCE 7-16 and EN 1990, in three families: service (soil), strength (concrete) and stability.

• Design basis: code, SBC and its basis (net or gross), founding depth, concrete, steel, cover.
• Column or wall size, and offsets for an edge column.
• Load cases Dead, Imposed, Snow, Wind and Earthquake, each with P, Mx, My, Hx, Hy — unfactored, at the top of the footing.
• Optional: your own combinations, soil unit weight, water table, base friction, passive resistance, crack-width limit, cost rates, plan grid step and longest L:B.
• Pile caps: pile diameter, safe compression, uplift and lateral loads, spacing and edge distance.

• Every check as demand ÷ capacity, with the combination, the clause and the working.
• Soil pressure from a tensionless biaxial solution; 3D model; strip shear and moment diagrams for any strength combination.
• Options explorer: up to 12 plans weighed, plotted by cost against governing ratio.
• FEM cross-check of the designed footing — a plate on soil springs, or a beam on springs for a strip — beside the rigid result and flagged when they disagree (for review; never changes pass or fail).
• Deep pile caps: a Strut-and-tie (deep cap) result group (struts, nodes, ties, anchorage). The ties (truss method, T = P·arm/z) are statics and always held — the design adds bars until they pass, and the notes say whether the tie or bending governs the bars. Under AS 3600 the struts and nodes govern too; under the other codes, where they fail but the sectional shear passes, the sectional shear is the check and the struts and nodes are shown for review. 3-pile caps: the triangle's truss — struts to one node at the column, the side ties by joint equilibrium, each resolved into the X and Y bars over its piles — so every tie, both ways, is carried by the bars.
• Bar-bending schedule (BBS tab), excavation, comparison and sensitivity tabs.
• Exports: calculation PDF, vector PDF, executive summary PDF, Excel, JSON; pile-cap DXF. Site Plan adds CSV, Excel, IFC, an FEM calculation report and DXF drawing sheets.

• AS 3600 and CSA A23.3 do not cover plain pads, the Other types, the Footing Schedule or Site Plan.
• Strap footings are designed in the Site Plan, which ties each column at the plot edge to the column it leans on; Other types runs the earlier cascade engine with one service load.
• Not modelled: trapezoidal footings under three or more columns, pile-group efficiency. The 3D view draws a trapezoid as its bounding rectangle.
• Site Plan: a corner column flush with two boundaries needs a two-way strap or tie-beam grid, which is not designed — it fails with that remedy named.