Introduction

It is commonly stated that 'a structure is a constructed assembly of joints separated by members' [1] and in timber engineering the joint will generally be the critical factor in the design of the structure. The strength of the structure will normally be determined by the strength of the connections; its stiffness will greatly influence the displacement behaviour, and member sizes are often determined by the number and physical characteristics of the type of connector being used rather than by the strength requirements of the member material.

The most common form of connector used in timber connections is the mechanical type, of which there are two main groups:

• Metal dowel type fasteners - where the load is transferred by dowel action, e.g. nails, screws, dowels and bolts, staples, etc.;

• Bearing-type connectors - where the load is primarily transferred by bearing onto the timber near the surface of the member, e.g. punched metal plate, split-ring, etc.

In this chapter, the design of metal dowel type connections subjected to lateral loading and/or axial loading is considered and bearing-type connectors are covered in Chapter 11. Connections subjected to the effect of a moment are addressed in Chapter 12.

The general information in 4.3 is relevant to the content of this chapter.

10.1.1 Metal dowel type fasteners 10.1.1.1 Nails

Nailing is the most commonly used method for attaching members in timber frame construction. Nails are straight slender fasteners, usually pointed and headed, and are available in a variety of lengths, cross-sectional shapes and areas. There are many types and forms of nails and the one most frequently used is the bright, smooth, steel wire type, commonly referred to as a smooth nail. It has a circular cross-sectional area, is manufactured from wire having a minimum tensile strength of 600 N/mm2, and in the United Kingdom are available in standard sizes ranging from 2.65 to 8 mm in diameter.

Nails can be plain or enamelled, etched, electroplated, galvanised or polymer coated to suit the finish required and the environment within which they are to be used.

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