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(7.44)

(3.72)

in Figure 10.18c. The other members are ignored. The strength of shear plane x is now calculated using the strength equations, ensuring that the embedment strength of each connected member takes account of the angle of the shear plane load relative to its grain direction. For example, in Figure 10.18c member 1 will be loaded parallel to the grain but member 2 will be loaded at an angle 01 to the grain.

Shear plane y between members 2 and 3 is now considered. A three-member symmetrical connection is formed around member 3 using member 2 as the outer member, as shown in Figure 10.18d, and the other members are ignored. Note that on this occasion the actual joint members can be used as the joint is already symmetrical. The strength of the shear plane is then derived as above. To consider all possible failure modes for shear plane y, a double shear connection involving member 2 as the central member with member 3 on either side, as shown in Figure 10.18e, must also be analysed as for the previous simulations.

From these analyses, the minimum strength of shear plane x and of shear plane y will be determined, ensuring that compatibility of the failure modes across the joint is taken into account. For the joint being considered an example of the requirement is shown in Table 10.11. The mode with the minimum strength in shear plane x is mode (h), consequently the shear strength of shear plane x will be 4.5 kN. Because modes (j) and (k) are not compatible with mode (h), they need not be evaluated (see values in brackets in the table), and mode (h) in alternative shear plane y becomes the y plane shear failure mode as it has the lowest value.

In addition to the above check, if the design force in a shear plane results in any member in a timber connection being subjected to a force component at an angle to the grain, the timber must also be checked for compliance with the requirements of 10.3.6.1.

See Examples 10.13.3 and 10.13.4.

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