ABSTRACT
In a complex structure, analysis is often carried out by computer methods using small-deflection elastic theory. In general, this results in many of the components of the structure being in axial compression. If these elements of structure are slim, then there is a possibility of these components buckling at very small axial loads. Very often the axial stresses may be small, but because they are in compression, the structural components catastrophically fail by buckling or instability. If the component is long and slender, then it can fail elastically, but if it is short, it can fail inelastically and in these cases, the elastic theory must be modified to cater for inelastic instability. This chapter shows to: define struts, beam-ties and beam-columns, appreciate the elastic instability of very long slender struts, determine the Euler buckling load for axially loaded struts, appreciate and use the Rankine-Gordon formula. It shows to: state the Johnson parabolic formula and derive the Perry-Robertson formula.
