Structural behaviour of cold curved beams

Abstract

Curved girders are highly used in roadways and bridges either for architectural or structural purposes. Cold bending is a relatively new method used in the construction sector to curve girders using point loads without any increase in temperature. This method is effective and has gained a lot of attention recently. While some studies have explored the effect of cold bending on the structural capacity of steel girders to resist static loads perpendicular to their plane of curvature, no work has been done to assess the behavior of these girders under cyclic loads. This project aims to study the effect of fatigue on cold bent steel girders. The study involves experimental testing as well as numerical modeling. Experimental testing consists of material testing followed by testing of hot-rolled I-section steel girders first bent about their weak axis, then loaded about their strong axis using cyclic loads. Results from the experimental testing were compared to results from finite element modeling in order to validate the latter. After validation of finite element modeling using results from experimental testing, it was found that cold bending creates residual stresses that affect girder behavior against fatigue but do not make it obsolete. Variations can be made on girders in order to improve their capacity against cyclic loading, such as adding stiffeners, changing loading configurations and boundary conditions. Finally, recommendations were given regarding the optimum testing configuration under service loads.