Stability of a Structure

the ability of a structure to withstand the action of forces attempting to drive it out of a state of equilibrium.

One of the primary requirements imposed on structures is that they possess both stability and strength. Loss of stability usually results in a shift or inclination of the structure. The stability of a structure is calculated or measured primarily in those cases where lateral forces act on the structure, such as hydrostatic pressure on a dam, lateral earth pressure on a retaining wall or bridge abutment, and seismic and wind loadings on tall structures. When the inclination of a structure is calculated or measured, the values of the tilting and restraining moments with respect to the outer foundation are compared. When a structure is checked for shifting, it is necessary to compare the shear forces (usually lateral) acting on the structure with the restraining (reaction) forces, such as those of friction or adhesion.