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Loading a structural element or a specimen will increase the compressive stress until the reach of compressive strength. According to the properties of the material, failure will occur as yield for materials with ductile behaviour (most metals, some soils and plastics) or as rupture for brittle behaviour (geomaterials, cast iron, glass, etc).

In long 'slender' structural elements (such as columns or truss bars), increase of compressive force F leads to failure due to buckling at lower stress than the compressive strength, according to Euler;

F_b = π² x E x I / l²

The 'slenderness' of the element depends on its length, the way the ends are supported and its cross section. The slenderness is expressed with the letter lambdaLambda (upper case Λ, lower case λ) is the 11th letter of the Greek alphabet. In the system of Greek numerals it has a value of 30. The upper-case letter Λ is used as a symbol for: The lambda particles in particle physics The set of l as; λ = l_b / √(I/A)

With λ and σ = F/A, Euler's formula can be rewritten for the buckling stress as; σ_b = π² x E / λ²

Compressive stress has stress units (force per area), usually with negativeNegative has meaning in several contexts: Negative and non-negative numbers Negative (photography) Negative (music) For other contexts see " positive". values to indicate the compaction. However in geotechnical engineeringGeotechnical engineering is concerned with the engineering properties of earth materials. Geotechnical engineers work with data from soil and rock samples to specify the requirements for man-made structures and earthworks that will be built on a site., compressive stress is represented with positiveIn common usage positive is sometimes used in affirmation, as a synonym for "yes" or to express "certainty". In mathematics, a number is called positive if it is bigger than zero. See negative and non-negative numbers. In functional analysis, a bounded li values.

Compare: tensile stressTensile stress (or tension) is the stress state leading to expansion (volume and/or length of a material tends to increase). In the uniaxial manner of tension, tensile stress is induced by pulling forces across a bar, specimen etc. Structural members in d

See also: structural engineeringStructural engineering is the field of civil engineering particularly concerned with the design of load-bearing structures. In practice, it is largely the implementation of mechanics to the design of structures, such as buildings, bridges, walls (includin, Hooke's lawIn physics, Hooke's law of elasticity states that if a force (F) is applied to an elastic spring or prismatic rod (with length L and cross section A), its extension is linearly proportional to its tensile stress σ and modulus of elasticity (E): :&De.