The structure may collapse or consolidate if the component of the structure are not in equilliberium condition. The main provision of any structure to be safe is to remains in statically and dynamically equilliberium.
The structure is said to be statically equilibrium if the structure has met the following condition
1) Algebraic sum of all vertical force acting on the body will be Zero.
2) Algebraic sum of all Horizontal force acting on the body will be Zero.
3) Algebraic sum of Moment from all side acting on the body will be Zero.
These are the three equations are called equation of statics.