Sensitivity of Steel Purlins to Changes in Application of Wind Loads

This project studied the effects of wind tunnel test loads applied to purlins in low rise steel buildings compared to those determined with currently recognized wind loading provisions. The National Institute of Standards and Technology (NIST) database of low-rise building wind tunnel test data, which was collected at the University of Western Ontario (UWO) boundary layer wind tunnel, was used to model a realistic wind load scenario. Pressure coefficient data recorded in the database was applied statically to individual purlins in a typical design for the size of buildings studied. These results were then compared to those obtained using the wind design provisions in ASCE 7-16 Chapter 30 for Components and Cladding. The primary data of interest was shear and moment values along the length of the purlins, which were modeled as continuous beams. Comparisons were made between the resultant shear and moment from both the wind tunnel load and ASCE 7-16 load values at 1-foot increments along the length of the purlin. The results showed that the overall peak values obtained from wind tunnel test loads were 3% to 49% higher than those calculated using ASCE 7-16 for purlins that were on the windward edge of the building. Purlins on the interior of the building varied in whether they exceeded the loads calculated with ASCE 7. Changing the height of the structure and the terrain roughness both increased the number of purlins that were lower than the values provided in ASCE 7-16 in the interior of the structure.