Fwn

Slip in member 2

= uinst2

(a) Connection

(b) Loaded timber/timber

(or wood product) connection

Member 1 - timber Member 2 - timber

(c) Loaded steel/timber

(or wood product) connection

Member 1 - steel Member 2 - timber

Fig. 10.23. Instantaneous slip in a connection.

concrete-to-timber connections may be taken to be 2 x Kser, if the structure being designed is sensitive to deflection behaviour it is recommended that a smaller value be used.

When deriving the strength of a multiple metal dowel type fastener connection loaded perpendicular to the grain, the actual number of fasteners, n, in the connection is used in the joint strength equation, and when deriving the strength parallel to the grain, the effective number of fasteners, nef, must be used. No guidance is given in EC5 on the value to be used to determine the stiffness of a connection and, irrespective of the angle of load relative to the grain, for single and double shear connections it is recommended that the actual number of fasteners, n, is always used.

The stiffness values given in Table 10.13 for Kser are the stiffness per shear plane per fastener, and for connections with n fasteners per shear plane, the connection stiffness, Kser,sc for single and Kser,dc for double shear configurations are given in Figure 10.24.

Where a clearance is required to permit the fastener to be fitted, e.g. with bolts, there will be additional slip in the connection caused by the take-up of this allowance. If the clearance (tolerance) provided is c (mm), usually taken to be 1 mm for bolts, the instantaneous slip for a connection with a single fastener and a single shear plane will be:

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