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Eurocode 5
Expertise

Eurocode 5

Introduction to Eurocode 5

The Eurocodes are a series of standards that establish common rules across the European Economics Area (EEA) for structural design using main construction materials such as concrete, steel. masonry, timber, aluminum and glass. They allow a designer to prove compliance with the requirements of the European Construction Product Regulation and National Building Regulations.

BS EN 1995, more commonly known as Eurocode 5 or EC5, is the standard for structural timber design. 

Considerable research from most member states has gone into these standards, and they are continually supported by a review evert five years. National standards bodies are required to help in the review process by collating the information relevant to their jurisdictions.

This Wood Information Sheet (WIS) is an overview of the subject with signposts to more detailed sources that are listed at the end. It outlines the major differences between Eurocode 5 and BS 5268-2 Structural use of timber which was withdrawn in 2010, and includes guidance on transitioning between the two.

Key Points

  • Eurocode 5 contains only essential rules and general formulae for design, eliminating the need for the material specific tables that were presented in the BS 5268 family of standards.
  • The UK National Annex (UK NA) to Eurocode 5 contains country-specific, nationally determined parameters (NDPs) and other information, where an option of national choice exists in Eurocode 5.
  • PD 6693-1 Recommendations for the design of timber structures to Eurocode 5: Design of timber structures. General. Common rules and rules for buildings (3) contains, among other things, non-contradictory practical advice extracted from the BS 5268 family of standards.
  • BS EN 1990 Eurocode. Basis of structural design (4) and BS EN 1991 Eurocode 1. Actions on structures (5) must be used in conjunction with the relevant parts of Eurocode 5 as they contain general principles, design situations, and loads and combinations that apply to all types of design.
  • Principles are Eurocode statements for which there are no alternatives, marked with a 'P' at the beginning.
  • Application rules, marked 'A' are generally recognised rules of procedures that satisfy principles and can be replaced by alternatives if deemed necessary. 
  • BS 5268-2 used 'permissible stress design' whereas Eurocode 5 uses 'limit state design' with ultimate and serviceability limit states.

Fasteners for Structural Timber: Nails, Staples, Screws, Dowels & Bolts

Introduction

Timber designers usually consider connection design to be the most difficult area in timber engineering. The traditional mechanical fasteners for structural timber are divided into two groups depending on how they transfer the forces between the connect members - 'dowel-type fasteners' and 'metal connectors'. 

This Wood Information Sheet (WIS) describes the dowel-type fasteners: nails, staples, screws, dowels and bolts. These fasteners can be CE marked in accordance with BS EN 14592. With these fasteners, the magnitude of load transfer between the connected members depends on the bending behaviour of the fastener as well as the bearing stresses developed in the timber along the shank of the fastener. Friction within the interface between the two connected members and axial pullout resistances could also contribute to the shear (lateral) capacity, depending on the fastener type. 

Metal connectors include fasteners such as split rings, shear-plates and punched metal plate fasteners where the load transfer is primarily achieved be bearing on to the surface of the members. This group is covered in a companion WIS 2/3-51 Timber engineering hardware and connectors (1).

BM TRADA recommends Eurocode 5 (2) for structural design of timber. However, This WIS includes a summary of variations when using BS 5268-2 Structural use of timber. Code of practice for permissible stress design, materials and workmanship (3).

This Wood Information Sheet (WIS) is an overview of the subject with signposts to more detailed sources that are listed at the end. 

Key Points

  • Two types of mechanical fasteners are used in structural timber design - dowel-types and metal connectors.
  • Dowel-type fasteners are nails, staples, screws, dowels and bolts.
  • Dowel-type fasteners can be CE marked to BS EN 14592.
  • Dowels and bolts are heavy duty fasteners whereas nails, staples and screws have comparable but lower capacities.
  • Proper fastener designs require the connection detailing to be appropriate as well as getting the capacity calculations correct.
  • Accounting for slip during service and protection of fasteners during fire are important aspects of a good fastener design.
  • Eurocode 5 contains calculation methods for fasteners in connections. 

 

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