Strength

Strength depends upon material properties. The strength of a material depends on its capacity to withstand axial stress, shear stress, bending, and torsion. The strength of a material is measured in force per unit area (newtons per square millimeter or N/mm², equivalent megapascals or MPa in the SI system, and frequently pounds per square inch psi the United States Customary Units system).
A structure fails the strength criterion when the loading stress induced by the loading is greater than the structural material capacity to resist the load without breaking. Or when the strain (percentage extension) is so great that the element no longer fulfills its function (yield).