Concrete Section Design
Design and check reinforced-concrete sections to Eurocode 2 (EN 1992-1-1) and TCVN 5574. Choose a section type below - each opens an interactive calculator covering ULS bending and axial-bending (N-M / P-M interaction), shear and SLS crack width and deflection, with step-by-step derivations and a clear PASS/FAIL. Rectangular and circular RC sections (columns and beams) and prestressed spun piles are available now.
Free online calculator with step-by-step working and one-click Excel (.xlsx) and PDF export.
Choosing the right concrete design tool
What this page is for
Reinforced concrete design splits into distinct member and region types, each with its own analysis method. This page is the starting point: it explains which calculator applies to which situation, so you use the right method rather than forcing a section check where a different model is required.
All the concrete tools support Eurocode 2 and, where relevant, TCVN 5574 as a separate engine rather than a translation - the two codes use different material models, partial factors and shear formulations, so switching code changes the answer.
Which tool for which situation
- Rectangular section
- Beams and rectangular columns - bending, N-M interaction, shear, crack width, deflection
- Circular section
- Circular columns, piers and bored piles - N-M interaction by chord integration
- Strut-and-tie
- Deep beams, corbels, pile caps, walls with openings - where beam theory does not apply
- Prestressed spun pile
- PHC hollow piles - prestress losses and the shifted interaction diagram
- Anchor bolt
- Fixings into concrete to EN 1992-4 - concrete failure modes, not the bolt
The question that decides the method
Ordinary section design assumes plane sections remain plane. That holds through most of a beam or column, and it is what lets a section be designed from a bending moment and an axial force alone.
It stops holding in disturbed regions - within roughly one member depth of a concentrated load, a support, an opening or an abrupt change of geometry, and throughout any member with a span-to-depth ratio below about three. There, strain is not linear across the depth and a section check gives the wrong answer regardless of how carefully it is done. Strut-and-tie is the method for those regions, which is why a deep beam and a shallow beam of the same materials need different tools rather than different numbers.
Assumptions and limits
These tools check sections and regions, not members and not structures. Slenderness and second-order effects are handled at section level where relevant, but overall frame stability, load path and the analysis that produces the design forces are separate exercises.
Serviceability results - crack width and deflection - depend heavily on creep, shrinkage and the assumed extent of cracking, so they are inherently less precise than ULS numbers and long-term values are typically two to three times the instantaneous ones. Detailing, anchorage and lap lengths, punching shear, torsion, fatigue, fire resistance and seismic design are outside the scope of all of them.