Compression Members |

Compression members, such as columns, are mainly subjected to axial forces. The principal stress in a compression member is therefore the normal stress, The failure of a However, when a compression member becomes longer, the role of the geometry and stiffness (Young's modulus) becomes more and more important. For a
For an In summary, the failure of a compression member has to do with the strength and stiffness of the material and the geometry (slenderness ratio) of the member. Whether a compression member is considered short, intermediate, or long depends on these factors. More quantitative discussion on these factors can be found in the next section. |

Design Considerations | |||||||||||||||||||||||

In practice, for a given material, the allowable stress in a compression member depends on the slenderness ratio Short columns are dominated by the strength limit of the material. Intermediate columns are bounded by the inelastic limit of the member. Finally, long columns are bounded by the elastic limit (i.e. Euler's formula). These three regions are depicted on the stress/slenderness graph below, The short/intermediate/long classification of columns depends on both the geometry (slenderness ratio) and the material properties (Young's modulus and yield strength). Some common materials used for columns are listed below:
| |||||||||||||||||||||||

| |||||||||||||||||||||||

In the table, r is the radius of gyration of the cross-sectional area, defined as .
Radii of gyration for standard beams, common beams, and other common areas can be found in the geometry section. |