Question $3[$Total: $14$ Marks$]$

Assuming $6$ mm in diameter nails $(8$ nails in $2$ rows along the length of the steel$-$to$-$timber broad$)$ being adopted in the following steel$-$to$-$timber joint $($using Radiata Pine$).$ Each nail passes through $10$mm steel board and gets into $35$mm of timber board.

a$)$ how much is the design capacity under combined permanent and imposed loading in wet service condition? $(10$ marks$)$

b$)$ What are the minimum spacings $($for predrilling condition$)?(2$ marks$)$