If you have access to Australian Standards nail lamination is covered in Section 2.4.5 of AS 1720.1, Timber structures, Part 1: Design Methods. Section 2.4.5 is titled Strength sharing between parallel members. The calculation of the modification factor for strength sharing, k9, is given as equation 22.214.171.124. For nail-laminated members AS 1684.2 Residential timber-framed constructionassumes nmem = 1.0 and ncom = number of combined sections in calculating k9. Or to keep it simple just refer to AS 1684.2, Section 2.3 where the recommended nail pattern is shown.
It is surprising how few resources there are for designing horizontally laminated timber. We haven’t been able to find any guides or tables so designs would have to be calculated from first principles according to the shear capacity of the fasteners (nails, screws or bolts). There is an example calculation here, but since it’s a US site all values are in imperial units: http://hyperion.usc.edu/courses/ame204/Homeworks/HW6.pdf.