Structural performance and design of hot-rolled steel SHS and RHS under combined axial compression and bending

Abstract

The structural behaviour and design of hot-rolled steel square and rectangular hollow sections (SHS and RHS) under combined axial compression and bending are studied in the present paper. Finite element (FE) models were developed and validated against existing experimental results on hot-rolled normal strength and high strength steel SHS and RHS under combined loading. Upon validation against the test results, an extensive parametric study was then performed with the aim of expanding the available structural performance data over a wide range of cross-section geometries, cross-section slendernesses, steel grades and loading scenarios. Both the experimentally and numerically obtained data were utilised for an assessment of the accuracy of the current design rules in European and American standards for hot-rolled steel tubular sections under combined loading. The comparisons revealed that the codified capacity predictions are generally somewhat conservative and scattered, due mainly to the neglect of strain hardening in the case of stocky cross-sections and the rather crude treatment of the partial spread of plasticity for Class 3 (semi-compact) cross-sections. The deformation-based continuous strength method (CSM) has been successfully applied to the Yun, X., Wang, Z. and Gardner, L. (2020). Structural performance and design of hot-rolled steel SHS and RHS under combined axial compression and bending. Structures, 27, 1289-1298.2 design of hot-rolled steel cross-sections under isolated loading conditions (i.e. compression or bending), and shown to provide more accurate and consistent ultimate resistance predictions than the existing design provisions. This paper presents the first study to extend the CSM to the design of hot-rolled steel SHS and RHS, made of both normal and high strength steels, under combined loading, underpinned by both experimentally and numerically derived data points. Advantages of the proposed approach include eliminating the discontinuity in the current codified methods, yielding more accurate and consistent resistance predictions and providing knowledge of the level of strain required to reach a given resistance. The reliability of the proposed method is statistically verified in accordance with EN 1990.

Behaviour and design of eccentrically loaded hot-rolled steel SHS and RHS stub columns at elevated temperatures

“…Note that for 300 °C, the alternative stress-strain curve given in Annex A of EN 1993-1-2 [5], which allows for strain hardening for temperatures below 400 °C, was adopted. The behaviour and design of hot-rolled steel SHS and RHS under combined loading at room temperature was investigated by Yun et al [44], and is thus not covered in the present study. In total, over 5000 numerical parametric results were generated, which are employed, together with the test results, to assess existing design approaches and new CSM proposals for determining resistances of hot-rolled steel SHS and RHS under combined compression and bending at elevated temperatures.…”

“…The FE models were validated using the experimental results of Pauli et al [31] summarized in the previous section and were subsequently employed in an extensive parametric study to obtain additional data covering a wide range of cross-section sizes, cross-section slendernesses, loading combinations and elevated temperatures. The FE models used for the present numerical investigation are similar to those developed in [37][38][39][40][41][42][43] for stub columns and in [43,44] for cross-sections under combined compression and bending, except that the material properties at elevated temperatures were adopted herein. A detailed description of the FE models and their validation against cross-sectional tests at room temperature were presented in [37,43,44]; thus, only the key numerical modelling aspects are reported in this section.…”

Stability and design of normal and high strength steel CHS beam-columns

“…Geometrically and materially nonlinear analyses with imperfections (GMNIA) were conducted to simulate the structural behaviour of the CHS members. The four-noded shell element with reduced integration S4R was used, as successfully adopted in previous investigations on tubular steel structures [24][25][26]. To improve the computational efficiency of the FE models, two modelling techniques, as adopted in [22], were implemented: (a) a non-uniform mesh was applied, with a finer element size of 0.1 Dt in the mid-span and a coarser element size of 0.5 Dt in the remainder of the models, and (b) only a quarter of the CHS members was modelled by exploiting of the symmetry about the mid-height plane and the mid-section plane perpendicular to the axis of buckling.…”

Structural behaviour and continuous strength method design of high strength steel non-slender welded I-section beam–columns

“…The CSM links the resistance of a cross-section to its deformation capacity through the adoption of a base curve and a material model that accurately represents the stress-strain relationship and allows for the beneficial influence of strain hardening [1]. Over the past decades, the scope of the CSM has been broadly expanded to stainless steel structures [2][3][4][5][6][7] aluminium structures [8][9][10], and more recently, carbon steel structures [11][12][13][14][15][16][17][18]. The CSM has gone through a systematic process of development including proposals of accurate CSM material models [2,9,12,19] and calibrations of CSM base curves [2,9,12,18], and has covered the design of cross-sections under compression [2,3,9,10,12,18], bending [2,3,5,8,9,11,12,17] and combined loading conditions [6, [12][13][14][15].…”