Imperfections in steel girder webs with and without perforations under patch loading

Post-buckling behaviour and strength of cold-formed steel lipped channel columns experiencing distortional/global interaction

“…The various configurations consist of linear combinations of the competing distortional and global buckling mode shapes with amplitudes (mid-span flange-lip corner vertical displacements) of (i) 10% of the wall thickness t (distortional mode) and (ii) L/1000 (global mode), values that are often adopted for cold-formed steel members and fall below the typical allowable geometrical tolerances, namely (i) b/500, prescribed by ECCS [20] for plates, and (ii) L/750, global tolerance recently stipulated in Europe. Although investigating the influence of the initial imperfection amplitudes on the column post-buckling behaviour and strength is outside of the aim and scope of this work, a very limited imperfection-sensitivity study is included in the paper -for further insight on this topic, the interested reader is referred to investigations carried out (i) by Schafer and Peköz [21] and Dubina and Ungureanu [22], in the context of cold-formed steel members, and (ii) by Maiorana et al [23], concerning steel girder webs. All numerical results presented were yielded by finite element analyses carried out in the code ABA-QUS [24] that (i) adopt member discretisations into fine 4-node isoparametric shell element meshes (preliminary convergence/ accuracy studies showed that it suffices to discretise the cross-section mid-line into 24 finite elements -10 in the web, 6 in each flange and 1 in each stiffener - Fig.…”

2d Models of Steel Beams under Patch Loading for Buckling Coefficient Assessment

“…The eigenbuckling problem, often approached through closedform solutions or numerical methods, is widely employed to analyze plates subjected to uniform axial load, bending moment, and shear [7,8]. Various analytical, experimental, and numerical investigations have explored elastic and plastic mechanisms [6,9,10] and the impact of tolerances and imperfections on elastic critical loads and ultimate resistance values [11,12].…”

Influence of longitudinal stiffeners on elastic stability of girder webs

“…In particular the use of the finite element method allowed the study of any geometry, initial imperfections [2,3], particular configurations of the load, like patch loading or localised symmetrical loads [4][5][6][7][8], and a wide range of constitutive laws for the material in non-linear range [9,8,24,10].…”