PCO formulations¶

What the program calculates, with which assumptions and within which range of validity.

This section applies in full to PCX, which shares the calculation core — PCX only adds the flexible pile caps.

The two paths¶

A pile cap can be designed in two ways, and the choice is not a matter of taste: it depends on how the cap behaves.

Rigid pile cap — the load goes down through compressed struts Blévot & Frémy · MBT (IBRACON)

Flexible pile cap — the cap works in bending, as a beam available in PCX

The rigidity criterion is in Checks.

The calculation chain¶

Column actions — N, Mx, My, Fx, Fy the input

NBR 8681 combination — normal ultimate cases consumes: actions

Pile reactions — analytical or by finite elements consumes: combinations and geometry

Strut model — Blévot or MBT consumes: reactions

Tie reinforcement consumes: strut model

Checks — nodes, punching, shear consumes: model and geometry

Detailing and report consumes: reinforcement and checks

The pages¶

Blévot & Frémy

The classic method: the internal truss, the strut check, the 1.15 factor and the code's complementary reinforcement.
Formulas by arrangement

The closed-form expressions for two to seven piles, with effective depth, stress limits, and main and complementary reinforcement.
MBT — Strut and Tie

The model of the IBRACON Commentaries on NBR 6118, with the spreading of the column load calculated instead of tabulated.
Finite elements

The pile cap as a solid, in a hexahedral or tetrahedral mesh — to check the assumptions of the strut model.
Load combinations

NBR 8681, with the correct treatment of favourable permanent actions.
Checks

Compression nodes, punching, shear and the rigidity criterion.

How to read these pages¶

Each one ends with the limits of validity, in its own coloured block:

Range of application

It delimits where the method holds. Read it as part of the result, not as a footnote — it is the information that separates using it from using it wrongly.