COLD-FORMED PURLIN-SHEETING SYSTEMS

Publisher Summary Purlin-sheeting systems used for cladding in roofs and walls commonly consist of cold-formed channel or zed section purlins, screw-connected to corrugated sheeting. This chapter presents a nonlinear finite element model for purlin-sheeting systems. The model incorporates both the sheeting and the purlin, and is able to account for cross-sectional distortion of the purlin, the flexural and membrane restraining effects of the sheeting, and failure of the purlin by local buckling or yielding. The validity of the model is shown by its good correlation with available experimental results. Cold-formed steel zed and channel section members are widely used as purlins or grits. Purlins are usually connected to the sheeting by way of a screw through the crest of the corrugated sheeting and the purlin flange. Due to the restraining action of the sheeting, the purlin tends to fail by localized plastic collapse or local buckling rather than overall flexural-torsional buckling. The sheeting provides two restraining effects to the purlin; shear and rotational effects. Both shear and rotational stiffness cause a significant increase in the capacity of the attached purlin and their negligence result in over conservative estimates of the purlin load-carrying capacity.