Introduction

When a connection in a structure is subjected to rotation, provided there is no relative movement between the members of the connection, all elements will be subjected to the same rotation. Under this condition, the connection is classified as rigid and will provide maximum rotational stiffness to the structure. At the other extreme where the members in a connection are held in position but free to rotate relative to each other, no moment can be transferred and this condition is classified as pinned. When the degree of fixity in the joint is between these states, it is classified as semi-rigid.

In timber design it is normal practice to assume that connections are either rigid or pinned, however, the reality is that in service they will, to varying degrees, exhibit semi-rigid behaviour. When a connection is subjected to a moment, the stress resultants in the connection are transferred between the connection members by the fasteners/connectors and movement in the connection will arise from a combination of movement due to the take-up of tolerance allowances, embedment of the fasteners/connectors in the connection members, and, where the fasteners being used are relatively flexible (e.g. nails, bolts, etc.), by deformation of the fasteners. As the stiffness of the members is generally large relative to the stiffness of the fastener configuration, their flexural, axial and shear deformations are normally small compared to the deformation arising from the combined embedment and fastener/connector deformation, and are normally neglected.

In this chapter, a design procedure for rigid and semi-rigid connections formed with metal dowel type fasteners or connectors and subjected to moment induced by lateral loading is addressed.

Unless otherwise stated, where reference is made to the use of fasteners, this is to be interpreted to mean either metal dowel type fasteners or connectors and when referring to the number of fasteners, when connectors are being used this is to be understood to mean the number of connector bolts.

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

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