1. Nature of xTdC
xTdC is a support tool for structural calculation, verification and technical documentation under the Italian NTC 2018 (Ministerial Decree of 17 January 2018) and Circular no. 7 of 21 January 2019, also referring to the Eurocodes the standards cite. The modules are: Cover sheet (Copertina), xAnalisi, xNeve and xVento, xStatica, xStatica CAD 2D, xAcciaio and xCA. Actual functions depend on version and plan. It is not a design, consulting, testing or certification service; preparing professional documents is a possible use, not a service provided by ONMAKE.
The word "Verified" in the title of the provisional patent application (U.S. Provisional Application No. 64/114,486), shown on the home page, is not an independent certification of the software or of results.
2. Professional responsibility and human review
Before using a result in a project, report, filing, administrative procedure, communication to the client or decision with safety effects, the designer or competent professional independently checks data, units, assumptions, model, applicable standards, combinations, formulas, module limits, checks not covered and the result. xTdC does not replace professional judgement, technical validation, regulatory checks, the signature and the responsibility of the qualified designer. The interface reminds users on the home page that the software may make errors, and the BETA acceptance screen reminds that the designer checks and signs the calculations and remains responsible for them.
Reports, tables, diagrams and printed pages are outputs generated from the data entered and the procedures of the version in use; they are not certification, attestation, independent validation or approval of the project by ONMAKE. A report intended for professional use should state the xTdC version and the professional-verification warning.
3. Standards, professional and teaching mode
Calculations follow NTC 2018 and Circular 2019 and, where the standard refers to them, the Eurocodes. xTdC has two modes: in professional mode (the default) calculations follow the standard and the professional inputs appear; the textbook simplifications used in Tecnica delle Costruzioni exercises are reserved for teaching mode. A teaching simplification must not be used for a real project.
4. Simplifications and checks not covered
Some modules use simplified methods or do not perform all possible checks; each module shows notices about its own limits, which form part of the terms of use and must be read before relying on the result. For example, in xAcciaio the bending-and-compression and buckling check (sections 8 and 9) uses a simplified formula in place of the coefficients of Annex B of EN 1993-1-1 §6.3.3 and does not calculate lateral-torsional buckling: for beams not laterally restrained, lateral buckling must be checked separately and the result may be on the safe side only in appearance; class 4 sections are treated as class 3 sections, with overestimated resistance; in bolted and welded connections some coefficients are simplified or to be set by hand.
Other points state their own simplifications in the text (for example the simplified effective flange width in xCA and the simplified method for fillet-welded connections in xAcciaio). The absence of a notice does not mean a check is complete.
5. Output, data and saving
Projects are kept in the browser (document 04) and in the files the user saves (JSON, CSV, XLSX, .xcad), and reports are printed from the browser. Saving in the browser is a recovery aid, not a guaranteed archive: keep copies of important projects. Data transfers between modules use units and meanings defined by the originating module: the user checks that imported data matches the expected meaning.
The "Open in Editor" command delivers the report to Editor Ultra as a document and sheets; the content is a copy of results already shown, not a new calculation.
6. Corrections and notices about results
ONMAKE may update xTdC to fix errors, security, compatibility, standards or features. When a correction materially affects results already obtained, ONMAKE publishes the change log and, where reasonably possible and necessary in relation to risk, informs potentially affected users so they can review their calculations. Users use the updated version and check notices.
Reports of calculation errors may be sent to info@onmake.it or support@onmake.it stating version, module, data used and expected result, without attaching third-party data that is not necessary.