North American approach to the design of continuous Z- and C- purlins for gravity loading with experimental verification

Abstract The design of cold-formed, through fastened, roof purlins requires a significant number of assumptions. The usual North American practice is to make the following major assumptions: constrained bending, full continuity through the lapped section, and a lap strength equal to the sum of individual purlin strengths. To verify these assumptions, test results of multiple span purlin systems were gathered from 10 laboratories. Of the 45 test results reported, 24 were found to be sufficiently documented for complete evaluation. Comparison of the test results and analysis/design procedures using the above assumptions and AISI specification provisions showed that the assumptions are valid.