Technical Booklet D Structure·Page 56·4B.15
Purlin bearing and spacing details
Purlins must have a minimum bearing length of 50 mm on supports, with clear span measured horizontally between supports. Design spacing of purlins is calculated as (A + B)/2, where A is the clear span of decking/sheeting and B is the purlin spacing.
clear span of purlin taken as the clear dimension measured horizontally between supports
the minimum purlin bearing length should be 50 mm
design spacing of purlins = (A + B)/2
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