AISI S908
Full Name
AISI S908 – Test Standard for Determining the Flexural Strength Reduction Factor of Purlins Supporting a Standing Seam Roof System
Scope
The American Iron and Steel Institute (AISI) has developed AISI S908, a standardized test method for evaluating the flexural strength reduction factor of purlins used in standing seam roof systems. This standard is crucial for ensuring the structural integrity and safety of these systems, as it addresses the unique challenges posed by the interaction between purlins and standing seam panels.
AISI S908 focuses on determining the flexural strength reduction factor for Z- and C-shaped purlins that support standing seam roof systems. This factor accounts for the potential reduction in a purlin’s flexural strength due to various factors, including:
- Lateral-torsional buckling: this phenomenon can occur when a purlin is subjected to bending about its strong axis, potentially leading to premature failure.
- Distortional buckling: this type of buckling involves localized deformation of the purlin’s cross-section, also affecting its load-carrying capacity.
- Effects of the standing seam attachment: the connection between the standing seam panels and the purlins can influence the purlin’s overall stability and strength.
The standard outlines a four-point bending test procedure for evaluating purlin behavior under simulated loading conditions. The test setup replicates the interaction between the purlin and the standing seam panels, allowing for accurate determination of the flexural strength reduction factor. Key aspects of the test procedure include:
- Specimen preparation: the standard specifies the required dimensions and tolerances for purlin test specimens.
- Loading conditions: the test involves applying a controlled load to the purlin specimen while simulating the restraint provided by the standing seam panels.
- Instrumentation and data acquisition: deflection measurements and strain data are collected during the test to monitor the purlin’s behavior.
- Failure criteria: the standard defines specific failure criteria, such as excessive deflection or the onset of local or global buckling, to determine the purlin’s ultimate strength.
By providing a standardized test method, AISI S908 enables engineers and designers to accurately assess the strength and stability of purlins used in standing seam roof systems. This information is crucial for:
- Optimizing purlin design: the flexural strength reduction factor obtained from the test can be used to refine purlin designs, ensuring adequate strength and preventing premature failures.
- Improving structural safety: by accounting for the potential reduction in purlin strength, AISI S908 contributes to the overall safety and reliability of standing seam roof systems.
- Facilitating code compliance: the standard provides a basis for demonstrating compliance with building codes and design standards related to the structural performance of standing seam roofs.
AISI S908 Accredited Laboratory
Applied Testing & Geosciences, LLC is accredited for performing tests using the AISI S908 standard. Our testing services can help you optimize your designs, ensure code compliance, and enhance the safety and performance of your standing seam roof systems.
Contact us today to learn more about how our testing services can benefit your projects.
Resources
Keywords
purlins; standing seam roof system; flexural strength reduction factor; flexural strength; failure load; ultimate load; negative moment; positive moment; bracing; deflection; yield strength; stiffness; fastener; clip; screw