Numerical Studies of the Rotational Stiffness of Purlin–Sheeting System

Abstract

In light-gauged steel purlin-to-sheeting roof systems, the attached sheeting can provide rotational restraints to the purlin. The magnitude of the additional rotational stiffness offered by the sheeting will affect the load bearing capacity of the purlin. The current design method in Eurocode3 (EC3) is less accurate in predicting the purlin-sheeting rotational stiffness as it neglects the effect of wall thickness of the purlin. An integral model is introduced based on the finite element method. Comparisons are made between numerical results and existing experiments and a good agreement is observed. Parametric studies are conducted based on the validated model to investigate the influences of geometric dimensions on the rotational stiffness. Two modified coefficients are proposed for calculating the rotational stiffness based on the codified formulae in EC3, where the effect of the wall thickness and the flange width of the purlin are both considered.

Buckling behavior of cold-formed C/Z-section purlins incorporating the effects of diaphragm and the screw location

“…A finite element model of I-section beams was developed considering different restraining effects from the sheeting on the flexural-torsional buckling strength (Hancock and Trahair, 1978). Other researchers (Gao and Moen, 2012; LaBoube, 1986; Vraný, 2006; Wang et al, 2018; Zhao et al, 2014) provided different approaches to calculate and calibrate the restraining stiffness of the purlin-sheeting systems. A number of methods (Li, 2004; Li et al, 2012; Ye et al, 2002, 2004; Zhang and Tong, 2016) have also been published to study the effects of the rotational and lateral restraints on the stress distribution and buckling behavior of C/Z-section purlins.…”