Cold bending steel beams

Abstract

The objective of this study is to assess analytically and experimentally the behavior of a full scale steel rolled shape (an IPE600 section) 6m long, 0.22m wide and 0.6m high cold curved by a proprietary cold bending process. Displacements and strains recorded during the experiment are compared to theoretical values and finite element results. The proprietary cold bending jig is project specific and is manufactured from steel and concrete and allows installation of the 6m long IPE 600 steel girder in a position that allows strong axis bending for self-weight e.g. self-weight effects can be neglected. The setup contains two built in custom made rollers that support and withstand experimental loads and two hydraulic jacks; one at the level of the lower flange and one at the upper flange for the purpose of simultaneous load application. The loads are applied at predefined intervals creating local bending and resulting in consecutive straight segments that idealize the curved shape of the girder. The load of 250KN is distributed by the cylinder head to the side of the flange over a plate 15cm wide and its intensity is incremented as required. The final radius of curvature reached in the experiment is around seventy meters. At reference stopwatch time, displacements and loads are recorded. Strain readings are continuously recorded from strain gauges on specialized data acquisition software. This research project proves that the cold bending system proposed can be used to deform steel girders horizontally to develop a smooth curved profile. Results based on an analytical solution and finite element analysis compared to measured values are in agreement at yield an in the inelastic range. Flaws in the steel yield stress, measurement of deformations and maximum readings of strain gauges did not allow validating the accuracy of the method in the fully-plastic and post-plastic ranges.