RC Pile Cap Design Calculator

Multi-code reinforced-concrete pile cap design — SANS 10100, BS 8110 and Eurocode 2. For 2, 3 and 4-pile caps under a column axial load and optional biaxial moment: rigid-cap pile reactions, main tension reinforcement by the truss / strut-and-tie method banded over the pile heads, a simple-bending cross-check, column and corner-pile punching, beam (face) shear with the enhanced-shear-near-supports allowance, minimum steel, bar anchorage past the pile centre and a printable clause-by-clause calc sheet.

Truss method to BS 8110 cl.3.11.4 with SANS 10100 materials; Eurocode 2 strut-and-tie per EN 1992-1-1 cl.6.5 & 9.8.1

Inputs

Pile cap

Name / mark

Design code

Column load (ULS design values)

Axial N (ULS)

Moment M_x

kNm

Moment M_y

kNm

Load eccentricity e_x / e_y

Add cap self-wt to N

Self-wt factor γ_f

SLS pile-check loads optional — 0 = not given, ULS used conservatively

Axial N (SLS)

Moment M_x (SLS)

kNm

Moment M_y (SLS)

kNm

Pile arrangement

No. of piles

Pile dia φ

Spacing s (c/c)

Edge overhang past pile face

Pile capacity R_all (geotech)

Pile tension capacity R_ten (geotech, 0 = none)

Cap & column geometry

Column c_x / c_y

Overall depth h

Cover (ground-cast)

Bar dia tie bars

Layers

Steel layout

Materials

Concrete f_cu

MPa

Rebar f_y

MPa

Concrete density γ_c

kN/m³

Shear (uncertainty inputs — cited defaults)

v_c constant 0.79/γ_m,v

(400/d)^¼ floor at 1.0 (unconserv.)

Crit. section offset frac × φ into pile

Enhance threshold s ≤ n×φ

Enhancement 2d/a_v

Cap on 2d/a_v 0 = uncapped

Force 1.5d punch even if s≤3φ

Anchorage & practice

Bond β f_bu=β√f_cu

Min spacing advisory ×φ

Min edge dist advisory

Pile cap plan

Section / elevation

Strut-and-tie model truss method

Design result

—

enter loading

Cap plan (b × L × h)	—
Pile reaction max / min	—
Effective depth d	—
Tie force / band T	—
Tie steel per band	—
Bending cross-check A_s	—
Beam shear v / v_allow	—
Col-face punch v₀ / v_max	—
Anchorage l_b / avail	—

Tie band

Design checks

Step-by-step calculation

Combined bar schedule — all pile caps

Every pile cap in the project, aggregated — banded tie bars each way over the pile heads. Marks are prefixed with each cap name. Use “Add pile cap” above to build the full schedule, then Download PDF (print → Save as PDF). Cut lengths per SANS 282:2004 (nominal; bobs/hooks and laps to the detailer where anchorage is short).

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This isn't a toy calculator

It runs the same engine philosophy as STATIX — a full structural suite validated against 221 closed-form and code benchmarks across analysis, design and connections — the full 3D modeller with native CBFEM is coming soon. Model the whole substructure, not just one cap.

Get early access →