SIST EN 1991-3:2026/oprA1:2026

SIST EN 1991-3:2026/oprA1:2026 is a CEN draft amendment to Eurocode 1, Part 3, on actions induced by cranes and machines. It updates the rules used to determine loads, dynamic effects, and fatigue-related classification for the structural design of crane and machine supporting structures. The draft is for enquiry and is intended to amend EN 1991-3:2026.

What does SIST EN 1991-3:2026/oprA1:2026 specify?

SIST EN 1991-3:2026/oprA1:2026 amends EN 1991-3:2026, which defines actions imposed by cranes and other machines, including dynamic effects where relevant, for the structural design of supporting structures. The underlying part applies to bridge cranes, gantry cranes and wall cranes travelling on fixed runways, and to fixed machines that cause harmonic dynamic loading on fixed supporting structures.

It also gives guidance on crane classification in terms of dynamic factors and fatigue actions. The principles can be applied to other cranes as well, which helps when a project uses crane arrangements outside the core list.

EN 1991-3 does not provide partial factors for actions, and it does not provide actions or design provisions for cranes and machines themselves. In practice, that means users must combine it with the basis of design standard and with manufacturer information.

What are the key requirements of SIST EN 1991-3:2026/oprA1:2026?

Cross-references and basis of design

The draft amendment replaces EN 1990:2023 with EN 1990-1:2023+A1:2026 throughout the document, and replaces undated EN 1990 with EN 1990-1. For users, this keeps the Eurocode references aligned with the current basis standard for new structures.

The introduction also adds a note pointing to EN 1990-2 where additional or amended provisions may be needed. That matters when a project needs rules beyond the base text.

Scope and seismic handling

The introduction now states that EN 1991 does not cover the specific requirements of actions for seismic design or assessment, and points to EN 1998 (all parts). In practice, seismic cases need to be checked against the earthquake design Eurocodes rather than treated as part of EN 1991-3.

Notation, tables and figures

Clause 3 updates Figure 3.1b and makes the relevant symbol definitions non-italic. This is a formatting correction, but it matters because the symbols are used in calculations and reports and should be copied exactly.

Clause 5 updates Table 5.1 note 2, and clause 6 updates Table 6.5 and 6.9.4(1). These are correction-style changes that keep the notes and formula reference consistent with the surrounding text and with EN 13001-2:2021.

Fatigue guidance

Annex A updates Table A.1 for the guidance on crane classification for fatigue design of crane supporting structures. For designers, that means the annex should be read with the revised notation when classifying cranes for fatigue-related checks.

What terms does SIST EN 1991-3:2026/oprA1:2026 define?

• Supporting structures - the structural parts that carry the crane or machine actions.
• Fixed runways - the fixed tracks on which bridge cranes, gantry cranes and wall cranes travel.
• Harmonic dynamic loading - repeated loading with a regular dynamic pattern from a fixed machine.
• Dynamic factors - values used to represent the dynamic effects of crane operation.
• Fatigue actions - repeated actions that matter for fatigue design of the supporting structure.
• Partial factors for actions - safety factors for actions, which are taken from EN 1990-1 rather than this document.
• National Annexes - the national choices used for regulatory safety values within the Eurocode system.

Who uses SIST EN 1991-3:2026/oprA1:2026?

SIST EN 1991-3:2026/oprA1:2026 is used by structural engineers who design crane supporting structures and by engineers working on machine-supporting structures with dynamic loading. It is also relevant to crane and machine manufacturers, because the structure designer relies on the action information they provide.

It is commonly used on projects involving bridge cranes, gantry cranes, wall cranes, and fixed machines that create repeated dynamic effects. Reviewers and technical managers use it to check that crane classification, fatigue guidance, and cross-references are being applied consistently.

What changed in SIST EN 1991-3:2026/oprA1:2026 from the previous edition?

SIST EN 1991-3:2026/oprA1:2026 amends EN 1991-3:2026 with these changes:

• updates the references to EN 1990 throughout the document
• adds a note in the introduction pointing to EN 1990-2
• revises the seismic wording in the introduction and points to EN 1998
• changes the wording in subclause 1.1 to use “this document”
• updates the normative reference to EN 1990-1:2023+A1:2026
• revises Figure 3.1b and symbol formatting in clause 3
• corrects note 2 in Table 5.1
• corrects the note in Table 6.5 and the formula reference in 6.9.4(1)
• updates Table A.1 in Annex A

Some of these are stated to be editorial corrections that improve document quality.

Which standards are used with SIST EN 1991-3:2026/oprA1:2026?

• EN 1990-1:2023+A1:2026 - the basis of structural and geotechnical design; it provides the partial factors and basis framework used with this part.
• EN 1990-2 - cited in the introduction note for cases where additional or amended provisions may be needed.
• EN 1998 (all parts) - gives the provisions for seismic design or assessment.
• EN 13001-2:2021 - referenced in clause 6 for the calculations linked to crane action assessment.
• Relevant execution, material, product and test standards - the foreword states that Eurocodes are intended to be used with these standards.

What does the SIST EN 1991-3:2026/oprA1:2026 document contain?

The document is a set of amendment instructions rather than a full restatement of the Eurocode part. It revises the Introduction, Scope, Normative References, Terms, Definitions and Symbols, clause 5, clause 6, and Annex A.

It includes an updated figure in clause 3, corrected symbol formatting, note changes in Tables 5.1, 6.5 and A.1, and a formula cross-reference correction in 6.9.4(1). These changes mainly support consistent notation, correct citations, and clearer fatigue-design guidance for crane supporting structures.