DESIGN BASED ON EUROCODES
Up until July 1, 2013, the design of metal structures in Ukraine was performed under the national regulatory frame (DBN, SNiP, DSTU, etc.). After the above date, a different set of regulations was approved; as a result, it is permissible now to apply European standards — Eurocodes — to building structures design as an alternative.
Eurocodes are a set of structural design standards developed by the European Committee for Standardization (CEN) at the beginning of the 1990s for covering the issue of support structure design. Together with European Standards, Eurocodes are a complete self-contained tool for managing reliability and monitoring durability of buildings, which correspondents to the national system's concept (see Table below).
The DBN and SNiP systems dealing with industrial, civil buildings, other structures, corrosion issues, etc.
The system of Eurocodes based on design, influences and loads for designing different structures, etc.
The DSTU and GOST systems in elaboration of the DBN and SNiP systems
The system of European Standards (EN) in elaboration of Eurocodes
Application of Eurocodes became legally effective as of July 1, 2013, in accordance with DBN A.1.1.-94:2010 "Design Of Structural Construction By Eurocodes. General Rules". Harmonized documents are issued with the designation DSTU-N B EN 1991 - EN 1999 and DSTU-N B V.1.2-13:2008 (EN 1990), most of them include a number of "Parts" and National supplements (Amendments to DSTU-N EN) that bring into force a relevant CEN document. CE-marking of construction products is mandatory in the EU (Standard 1090). According to this Standard, the loading capacity of metal structures shall be estimated by Eurocodes.
Resolution of the Cabinet of Ministers of Ukraine No. 547 dd. May 23, 2011 (with amendments) approves the Procedure for application of construction standards developed based on national technological traditions and construction norms harmonized with the EU regulatory frame. This Procedure covers the structural design of buildings and construction facilities (new and reconstructed buildings) that, according to their consequence class, belong to the structures with small (CC1), moderate (CC2), and high (CC3) consequences.
In the design assignment, the Customer and the Designer together shall select the type of regulatory frame, under which the structures should be designed.
The project design documentation for a facility may not contain different applicable sets of construction norms.
Each country (its National standardization agency) shall implement a Eurocode, or a part of it, as a country's National standard by publishing a translated (identical) text. National supplements to each implemented document shall be published on behalf and with permission from national competent authorities and shall account for specific geographic and climatic conditions (for instance, zoning maps for snow covering and wind pressure), living conditions, and established safety levels.
For structural steel design, the core regulation is DSTU-N B EN 1991 - EN 1993-1-1:2010 "Eurocode 3. Structural steel design".
Eurocode 3 applies to the structural steel design of buildings and facilities for civil use. It satisfies the rules technical requirements to safety and operation of structures, basics of their design and checking calculation provide for in EN 1990 – Basis of structural design.
Eurocode 3 covers only the requirements for loading capacity, operability, durability, and fire resistance of steel structures. Other applicable requirements, for instance, thermal and sound insulation, are beyond its scope.
Eurocode 3 is intended for use together with the following regulatory documents:
- EN 1990 "Basis of structural design";
- EN 1991 "Actions on structures";
- EN, ETAG, and ETA on building products attributed to steel structures;
- EN 1990 "Structural steel manufacture. Technical requirements";
- EN 1992 – EN 1999: in respect of the parts related to steel structures or their components.
Eurocode 3 is structurally divided into the following parts:
EN 1993-1 Structural steel design. Core provisions. General rules and rules for facilities.
- EN 1993-2 Structural steel design. Steel bridges.
- EN 1993-3 Structural steel design. Towers, posts, and ventilation pipes.
- EN 1993-4 Structural steel design. Silos, reservoirs, and pipelines.
- EN 1993-5 Structural steel design. Piles.
- EN 1993-6 Structural steel design. Crane substructures.
It is required to account for general rules set up by EN 1993-1 when applying EN 1993-2 – EN 1993-6. The rules stated in EN 1993-2 – EN 1993-6 are supplementary to the general rules stipulated by EN 1993-1.
EN 1993-1 "General provisions. General rules and rules for buildings" includes the following:
- EN 1993-1-1 Structural steel design. General rules and rules for buildings.
- EN 1993-1-2 Structural steel design. Structural fire resistance design.
- EN 1993-1-3 Structural steel design. Cold-formed elements and sheeting.
- EN 1993-1-4 Structural steel design. Stainless steels.
- EN 1993-1-5 Structural steel design. Plated structural elements.
- EN 1993-1-6 Structural steel design. Strength and stability of shell structures.
- EN 1993-1-7 Structural steel design. Strength and stability of plated structures subject to out-of-plane loading.
- EN 1993-1-8 Structural steel design. Calculation of joints.
- EN 1993-1-9 Structural steel design. Fatigue of steel structures.
- EN 1993-1-10 Structural steel design. Selection of steel by impact toughness and through-thickness properties.
- EN 1993-1-11 Structural steel design. Design of steel structures with tension components.
- EN 1993-1-12 Structural steel design. Additional rules for structures made of high-strength steel.
Principal differences from the national regulatory frame
Among the principal differences between structural steel design approaches based on Eurocodes and on corresponding DBNs, the following is noteworthy:
- Eurocodes are intended for computer-aided calculations, not manual. In practice, Europe widely uses software packages that cut down time on routine operations. Specialized software for implementing different aspects of calculation rules by Eurocodes has now been developed in our country; in particular, in the packages LIRA-SAPR and SCAD.
- Depending on the specific function of equipment, European rules contain the requirements to factor in geometrical and physical nonlinearity. In practice, when performing static calculations, it is geometrical nonlinearity that is most often considered.
- When performing static calculations, Eurocodes require adjustment for theoretical initial discrepancies in two ways:
1. Simulation of a system with geometrical deflections;
2. Assigning equivalent forces that would simulate discrepancies.
In practice, the second option is recommended for use.
- By their loaded and strained conditions, transverse junctions of elements are divided into 4 classes, while DBN defines only 3 such classes. The process of class designation is in essence a check on the loss of local resilience of parts of a junction under normal loads. The class of junction determines formulas for further calculation of an element's parameters.
As to the system of partial reliability factors defined by material and operating conditions, etc., DBNs comply with Eurocodes. In general, however, Eurocodes consider the above factors as general (reduced) reliability factors calculated by loads applied and load-bearing capacity.
- Eurocodes do not contain mandatory restraints as to flexibility and movement of elements. On the issue of controlling deformations, Eurocodes refer to National supplements of every country in which a system of relevant regulations must be approved.
- In Eurocodes, the main geometrical characteristic of welded joints is its height (taken perpendicularly from the top of the assumed crossing of the joint to the external facet-hypotenuse), not its leg. In addition, there is no differentiation between the check-up of a welded joint strength by weld metal and by weld fusion boundary. It is generally assumed that the weld fusion boundary has the same strength as the parent metal, and destruction may occur only through the weld metal.
- In Eurocodes, basic checkups of bolted connections are suplemented with checkups on tearing of a crossing's part.
The above differences between the European and national regulations are not fundamental; first and foremost, they are associated with different levels of design technology and manufacture of metal structures, traditional methods used in the sector, and with different levels of standartization and quality control in manufacturing.
Further information on the application of Eurocodes and examples of structural estimates can be found in publications and video materials of the USCC:
- Estimates for steel structures of buildings according to Eurocode 3 and Ukraine's national supplements. Manual on DSTU-N B EN 1993-1-1:2010
- Estimates for steel structures of buildings according to Eurocode 3 and Ukraine's national supplements
- Examples of estimates for steel structures of buildings according to Eurocode 3 and Ukraine's national programs
DESIGN OF SUPPORTING BUILDING STRUCTURES ACCORDING TO EUROPEAN REGULATIONS
The USCC, in cooperation with the Construction Designers Guild, teaches seminars on "Design of building support structures by European rules" to advance the professional skills of designers.
Program participants who have completed the full course and passed the qualification exam shall receive a Certificate of advanced training.
These Certificates shall be considered as documentary proof of obtaining the advanced training that each certified specialist must complete once in five years.
The schedule for this future "Eurocodes" advance training program will be made public later.
The course program includes lectures and practical complex calculation tasks on construction design:
- Changes and amendments to Ukraine's regulatory framework
- Basics for structural reliability, loads and influences by Eurocode 0 and Eurocode 1
- Foundations by Eurocode 7
- Steel structures by Eurocode 3
- LIght thin-walled steel structures by Eurocode 3
- Fire protection by Eurocode
- Reinforced steel structures by Eurocode 2
- Steel-concrete composite structures by Eurocode 4
- Stone structures by Eurocode 6
- Wooden structures by Eurocode 5>
- Joints and connections by Eurocode
- Automation of calculations by Eurocode
- Energy-saving and certification of buildings — European regulations and best practices