The Theoretical And Test Study Of Integral Stability For Homemade Hot-rolled H-section Beam

The Integral stability capacity for homemade rolled H-section steel beam under uniform moment and the applicability of the design code (GB50017) are analyzed entirely in this paper. Both the theoretical and experimental investigation are made. It gives a chance to master and popularize homemade rolled H-section steel.In the conduct of the research, the commercially available multipurpose finite-element program ANSYS is used. The influence of residual stresses on the inelastic lateral buckling strength of rolled H-section steel beam is studied firstly. It shows that the presence of residual stresses decreases the inelastic lateral buckling strength significantly for beams of intermediate length and the residual stress level at the flange edges is the most important factor affecting the stability capacity. But when RF increases 0.2,the critical moments only decreases about 5%,which makes it possible that only one residual stress model is used for all homemade rolled H-section beam.In this research, the quadratic parabola pattern of residual stress distribution with Rp=-0.3 is applied to the BEAM189 beam element provided by ANSYS. Six sections with three dirTerent items (HW\ HM, HN) are considered. The whole buckling course of beams with different length is simulated by ANSYS and the critical moment is calculated in every case.The analysis results indicate that the method offered by GB50017 is appropriate for HN and HM section steel beams, especially for HN sections, while it is conservative excessively for HW-section steel beams because it ignores the effect of major axis curvature on beam stability. It is suggested that this type (HW) be treated separately.The formula calculating stabilization coefficient of HW-section steel beams is induced according to ANSYS's results. This formula is based on beams under uniform moment, but under other loading cases, it may also be used.The analysis shows, error distribution caused by the simplified torsion moment of inertia in GB50017 formula accord with a certain rule: generally, the formula gives conservative estimated valuesfor small size sections and just the reverse is true for large size sections. For HN sections whose height higher than 700mm (including 700mm) or the sections whose height equal to 500mm or 600mm but marked with "#", the code formula gives unsafe values. A more reasonable formula for these sections is suggested in this paper.Simplification formulary of stabilization coefficient for short beams is conservative excessively for homemade rolled H-section steel beam, based on the GB50017 code. Reference [21] modified this formulary. A further modification is made for HW-section beams taking the effect of major axis curvature into account in this paper.The above-mentioned modified simplification formularies are accurate than the code formulary, but their error increases with the slenderness ratio λy . For members with slenderness ratio larger than120, , these formularies are too conservative. This paper offers a relative simplified formulary forthe members with slenderness ratio no larger than 150 . this formulary is a little more complexbut much more accurate.At the same time, a test is carried out for 14 hot-rolled H-section beams to testify this paper's conclusion.