Codes for the design of strengthening
Strengthening reinforced concrete with composites is a matter of structural design, not of choosing a material. The codes here fall into two groups: codes of practice for the design of strengthening, and standards for adhesive joints and for the materials themselves.
| Document | What it governs | Status as of October 2026 |
|---|---|---|
| SP 164.1325800.2014 “Strengthening of reinforced concrete structures with composite materials. Design rules” | Calculation of reinforced concrete structures strengthened or restored with externally bonded composite reinforcement systems, and the design of these systems | Approved by Order of the Russian Ministry of Construction No. 452/pr of 08.08.2014, in force since 01.09.2014; Amendment No. 1 (Order No. 781/pr of 14.12.2020) since 15.06.2021. There is no newer approved edition in the register of codes of practice |
| SP 349.1325800.2017 “Concrete and reinforced concrete structures. Rules for repair and strengthening” | Design of the repair and strengthening of concrete and reinforced concrete structures, including with rolled steel sections and composite materials | Order of the Russian Ministry of Construction No. 1647/pr of 12.12.2017, in force since 13.06.2018; Amendment No. 1 (Order No. 852/pr of 28.11.2023) since 29.12.2023 |
| SP 63.13330.2018 “Concrete and reinforced concrete structures. Basic provisions” | The basis for reinforced concrete design to which SP 164 refers | In force since 20.06.2019, with Amendments No. 1 and No. 2; replaced the 2012 edition |
| GOST 32943-2014 | Adhesives and adhesive joints of strengthening elements | Interstate, in Russia since 01.07.2015, Amendment No. 1 since 01.06.2025 |
| O’zMSt EN 1504-4:2025 | Products and systems for structural bonding | National standard of Uzbekistan, in force since 29.01.2026 |
What SP 164.1325800.2014 covers
The code of practice applies to the design of strengthening and restoration of reinforced concrete structures of industrial and civil buildings and facilities with externally bonded reinforcement systems made of thermosetting polymers reinforced with carbon or glass fibres. It relates to structures of normal-weight and fine-grained concrete covered by SP 63.13330 and covers calculations for strength, crack formation and deformations. Since Amendment No. 1, the code’s list of references includes test methods for composites and plastics in tension (GOST 25.601-80, GOST 11262-2017), methods for determining the strength of concrete in structures (GOST 22690-2015, GOST 17624-2012, GOST 28570-2019, GOST 18105-2018) and survey rules to GOST 31937-2011. SP 349.1325800.2017, after its own Amendment No. 1, refers to SP 164.1325800.2014 with Amendment No. 1 and to SP 329.1325800.2017, the code of practice for surveys after a fire.
External reinforcement layouts
- Bending — beams, girders, slabs, bottom chords of trusses, eccentrically compressed columns with an eccentricity greater than 0.1h: strips or plates along the tension zone.
- Shear force — the zones of beams and girders near the supports: fabric stirrups wrapping the section on two or three sides, or full wrapping.
- Compression — columns, piers between openings and compression members of trusses with an eccentricity of no more than 0.1h: fabric jackets transverse to the axis that confine the lateral expansion of the concrete.
- Tension — tension members of trusses: longitudinal strips.
The number of layers, the layout and the end anchorage are determined by calculation using the survey data — the actual strength of the concrete, the condition of the reinforcement, the loads. External reinforcement does not stop corrosion of the bars inside the concrete, so its cause is eliminated before strengthening: the concrete is restored and the reinforcement protected to principles 3, 7 and 11 of GOST 32016-2012.
Substrate requirements
The flatness of the surface for CFRP is checked with a straightedge. The tolerances in SP 164.1325800.2014 are tighter than in the recommendations of the international federation fib (Bulletin 14):
| Measuring length | SP 164.1325800.2014 | fib, Bulletin 14 |
|---|---|---|
| 2 m | 5 mm | 6–10 mm |
| 0.3 m | 1 mm | 2–4 mm |
In addition to flatness, before installation the tensile strength of the concrete in the strengthening zone is determined by the pull-off method, spalls, blowholes and cracks are repaired, external corners are rounded for fabrics, laitance is removed down to a sound open structure, and the surface is cleaned of dust. The numerical criteria — the minimum pull-off strength of the substrate, the rounding radius, the permissible moisture content — are set by the design and the system documentation. Application guides quote, for example, a pull-off strength of at least 1.4 MPa, a rounding radius of at least 20 mm and a substrate moisture content of no more than 4 % by mass, as well as a minimum actual concrete class of B15 for members in bending and B10 for compression members; check these values against the current edition of the code of practice and the calculation.
Materials and test methods
In the documentation for CFRP systems, material properties are confirmed by international methods:
| Material | Properties | Method |
|---|---|---|
| Carbon fabrics | Tensile strength and modulus of elasticity of the fibre, elongation at break | EN ISO 10618 — tensile testing of resin-impregnated carbon fibre yarn |
| Plates and bars | Tensile strength and modulus of elasticity, elongation | EN 2561 — tensile testing of unidirectional CFRP parallel to the fibres (aerospace series) |
| Epoxy resins and adhesives | Tensile strength, elongation, modulus of elasticity | EN ISO 527-3 — tensile testing of plastic films and sheets |
| Adhesives | Lap shear strength in tension | EN 1465 — according to a caveat in the standard itself, it is not intended for the design of structural bonded joints |
| Adhesive joint with concrete | Properties of adhesives and adhesive joints of strengthening elements | GOST 32943-2014; EN 1504-4, in Uzbekistan O’zMSt EN 1504-4:2025 |
Results from different methods are not comparable: the fibre properties to EN ISO 10618 and the properties of a finished plate to EN 2561 describe different objects, and the design uses the characteristics provided for in the method of the chosen code. SP 164.1325800.2014 refers to GOST methods — GOST 25.601-80 for polymer matrix composites and GOST 11262-2017 for plastics. The service temperature limit and the protection of the resins against ultraviolet light are as per the documentation for the specific system.
What applies in Uzbekistan
In the catalogue of urban planning codes of the research institute for technical norms and standardization of the Ministry of Construction we have not found a separate code on strengthening reinforced concrete with composites. ShNK 2.03.01-24 is the code for concrete and reinforced concrete structures, ShNK 1.04.01-23 governs the survey that precedes strengthening, and ShNK 2.03.14-22 deals with concrete structures with composite polymer reinforcement, that is, internal rather than external reinforcement. So the basis for the strengthening design — SP 164.1325800.2014, SP 349.1325800.2017 or a foreign guide — is recorded in the design brief. Of the material standards, O’zMSt EN 1504-4:2025 applies in Uzbekistan, and according to the EASC catalogue the republic has joined the interstate GOST 32943-2014. Types of systems and materials are described on the “Strengthening structures with composites” page.
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