Modeling and testing of three-point bending of rectangular hollow sections for vehicles and highway guardrails

Abstract

Steel hollow sections are common for transport engineering, vehicles, highway guardrails. The special requirements for strength and stiffness are determined by tests. The three-point bending test experimental and FEM research were carried out on steel rectangular hollow sections (RHS) with a cross section of 40 mm × 50 mm, manufactured in two ways: (a) by cold bending of steel strips on roll-forming mill in semi-closed section with a longitudinal gap of 0.5 mm between the edges formed on a 40 mm web (B-RHS); (b) similar cold roll-forming to the closed section and welding with a longitudinal weld along the web middle of 50 mm (BW-RHS). As a result, the graphs and analytical equations for relating the force (P) and deflection (f) at load on 50 mm and 40 mm webs were obtained, and revealed the advantages of bent-welded sections (BW-RHS) by stiffness and strength. FEM was performed using the SolidWorks CAD/CAE system for various RHS wall thicknesses (t = 1.93 mm, 1.84 mm and 0.7 mm). It is shown that the BW-RHS design increase the stiffness by at least 50%, reduce the wall thickness by 61.9% while maintaining the same stiffness and ensuring the high strength indices for the case of least loading on the larger web, i.e. the maximum stresses in the RHS webs will be 2.33 times less than the yield stress of low-carbon steel.