EN 1994-2:2026/prA1

EN 1994-2:2026/prA1 is a CEN draft amendment to EN 1994-2:2026, the Eurocode part for the design of composite steel and concrete bridges. It updates bridge-design rules for materials, structural analysis, ultimate and serviceability limit states, and composite plates for engineers working on bridge projects.

What does EN 1994-2:2026/prA1 specify?

EN 1994-2:2026/prA1 specifies changes to the bridge part of Eurocode 4, which gives design rules for steel-concrete composite bridges and bridge members. The amendment is supplementary to the general rules in EN 1994-1-1 and is presented as a clause-by-clause update to the base standard.

The document is organized as a European foreword followed by the modification texts for those clauses. In practice, that means it is meant to be read together with EN 1994-2:2026, not as a standalone design code.

What are the key requirements of EN 1994-2:2026/prA1?

EN 1994-2:2026/prA1 mainly revises terminology, analysis parameters, fatigue notation, and a serviceability stress check. For bridge design teams, the practical effect is that some symbols, cross-references, and calculation expressions change, so project documentation and design spreadsheets need to follow the updated text.

Clause 3 - terms, definitions and symbols

• The symbol set is updated, including revised definitions for several shear-force and moment symbols, a new compressive stress reduction factor k_sl, and a new factor k_s for fatigue calculations. This matters because the design equations depend on the exact symbol definitions used in the standard.
• The symbol for bar diameter is changed to ϕ_s. That matters in detailing and when the standard gives bar-size limits or formula input ranges.

Clause 5 - materials

• Clause 5.1 is revised so that the rules from EN 1994-1-1 apply unless they are limited to buildings. For bridge work, that keeps the material rules aligned with the general composite design basis while avoiding building-only limitations.

Clause 7 - structural analysis

• The coefficient in 7.4.2.5(2) is changed to 12 x 10^-6 per °C. This affects temperature-related structural analysis, so bridge designers need to use the updated thermal value in their checks.

Clause 8 - ultimate limit states and fatigue

• Clause 8.3.3 now points the bending-shear interaction check to EN 1994-1-1:2026, 8.2.2.5. That tells the designer where to assess combined actions instead of relying only on the bridge part.
• Clause 8.3.4 and Figure 8.3 replace z_s with z_sf, which is the distance used for filler beam composite sections. This affects the geometry used in resistance calculations.
• The fatigue clauses update the stress-range notation to Δσ_e,2, Δσ_e,2,ten and Δτ_e,2, all related to 2 x 10^6 cycles. The figures and formulas are also aligned with that notation, so fatigue assessment is based on the revised symbols and curve descriptions.

Clause 9 - serviceability limit states

• Clause 9.2.2(1) limits excessive creep and microcracking by restricting concrete compressive stress for the characteristic load combination using k_sl f_ck in line with EN 1992-1-1:2023, Table 9.2. A National Annex may give alternative values. In practice, this is a key serviceability check for concrete stress control.

Clause 11 - composite plates

• Clause 11.4 clarifies wording for flange outstand geometry. That matters for detailing and for reading the plate rules without ambiguity.

What terms does EN 1994-2:2026/prA1 define?

• L_A-B - the introduction length of concentrated shear force.
• M_s,Rd - the part of the design bending moment resistance of a filler beam composite section provided by the reinforcement.
• V_a,Ed - the design value of the shear force acting on the structural steel section.
• V_c,Ed - the part of the vertical design shear force in the reinforced concrete part.
• V_Ed - the design value of the shear force acting on the composite section.
• k_sl - the compressive stress reduction factor.
• Δσ_e,2 - the damage equivalent normal stress range related to 2 x 10^6 cycles.
• ϕ_s - the diameter, or size, of a steel reinforcing bar.

Who uses EN 1994-2:2026/prA1?

EN 1994-2:2026/prA1 is used by bridge designers, structural engineers, checking engineers, and specifiers working with composite steel-concrete bridges. It is also relevant to quality managers and buyers who need to verify that bridge designs, calculations, or technical specifications follow the Eurocode bridge rules. Bridge construction teams use it when reviewing materials, analysis assumptions, fatigue checks, serviceability limits, and composite plate details.

What changed in EN 1994-2:2026/prA1 from the previous edition?

EN 1994-2:2026/prA1 amends EN 1994-2:2026. The amendment updates Clause 0, revises symbols and definitions in Clause 3, changes the material reference in Clause 5, adjusts a thermal coefficient in Clause 7, updates bending-shear and fatigue wording and notation in Clause 8, adds a serviceability stress limit in Clause 9, and clarifies composite plate wording in Clause 11.

Which standards are used with EN 1994-2:2026/prA1?

• EN 1994-1-1 - provides the general composite steel-concrete design rules that EN 1994-2 uses as its base.
• EN 1994-1-1:2026 - is referenced for the updated bridge-related cross-checks in Clause 5 and for bending-shear interaction in Clause 8.
• EN 1990-1 - is referenced in the symbols and definitions clause.
• EN 1992-1-1:2023 - supplies the concrete stress limit used in the serviceability check in Clause 9.

What does the EN 1994-2:2026/prA1 document contain?

EN 1994-2:2026/prA1 contains a European foreword and seven amendment clauses covering the introduction, terminology, materials, structural analysis, ultimate limit states, serviceability limit states, and composite plates. The text is made up of replacement paragraphs, revised symbols, edited formulas, and corrected figure labels. It also notes editorial corrections that improve the document without changing the technical meaning in the consolidated publication.