Friday, March 4, 2016

Overall buckling analysis of frames- Approximate methods

method of overall buckling load are included because it indicates an upper bound for the critical gravity load and it allows an assessment of the relative vulnerability of the building to transverse buckling or torsional buckling and for structures which an approximate p-delta analysis to amplification factor for the displacements and moments.

Shear mode

this mode is when double bending of the columns and girders buckling occurs in resistant frames as a result of story sway.

shear buckling

Flexural mode

in this mode, the entire structure buckles as a flexural cantilever by axial deformations of the columns. the greater the slenderness of structure it becomes more vulnerable  to instability in the flexural mode as opposed to the shear mode.

flexural buckling in structure

Combined shear and flexural modes

this is a contribution of shear and flexural modes, in this case of the buckling of a vertical cantilever with a gravity load as its top, below solution exists

1/Pcr = 1/Pf + 1/Ps

Pcr, Pf and Ps = critical loads for the combined, flexural and shear modes of buckling respectively.

flexural-shear buckling in structure

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