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, or the equivalent mega pascals or MPa in the SI system and often pounds per square inch psi in the United States Customary Units system).
A structure fails the strength criterion when the stress (force divided by area of material) induced by the loading is greater than the capacity of the structural material to resist the load without breaking, or when the strain is so great that the element no longer fulfills its function.