Design of purlin sizes is based on an analysis of bending members as a simple beam.
The length of the purlin from truss to the truss is taken as the span length needed for the single span, simply supported beam formula.
The length of the purlin from truss to the truss is taken as the span length needed for the single span, simply supported beam formula.
This is a conservative approach as it provides for a large moment than that obtained by true engineering analysis
This excel sheet provides the design of c purlin.
This excel sheet provides the design of c purlin.