DEFLECTIONPREDICTIONOFCOLDFORMED C- SECTIONROOFPURLINS

Abstract

Cold-formed steel (CFS) sections are widely used on modern roof steel structure building. The majority of thin walled open cross-section is used as purlin members. Those purlin-sheeting systems have been presented to several theoretic and practical applications over the past 30 years but the complications of the systems have led to large difficulty to be able to develop a new model. The purlins are asymmetric there for unavoidably produce a torsional moment that makes twisting or warping deformation and bending deflection. (non-linear) elasto-plastic finite element model, able to predict the role of purlin deflection with no need for both available empirical input or over simplified is presented in this paper. Consequently, the stability model is capable of assess the cross-sectional distortion of the purlin, and the failure of purlin by local buckling. The validity of the proposed model is described by its perfect similarity with empirical results. An equation is developed to calculate the CFS- C shaped purlin deflection subjected to biaxial bending through finite element model analysis and statistical regression analysis.