What is Structural Equilibrium? | Translational & Rotational equilibrium

Equilibrium can be defined as a state of balance achieved by a structure or a state of rest occurred when all the forces are equal and opposite to each other.

What is Structural Equilibrium

In Structural analysis and structural design, we focus more on the magnitude, direction and the point of application of the forces as well as the resultant forces in order to ensure the state of equilibrium. 

Fig.1: (a)  The resultant force obtained after resolving must be provided with a reaction equal and opposite for maintaining the equilibrium (b) The moment at the cantilever support is the reaction formed that is equal and opposite to the force formed due to the point load at the end of the beam.

In more easy words, a structural element will be in equilibrium when it react with an equal and opposite force to that applied on it.

Conditions of Equilibrium

For a rigid body to be in equilibrium, two conditions are:

  1. The vector sum of all the forces must be equal to zero. This will ensure translational equilibrium
  2. Next, the algebraic sum of all the moments of forces about any point must be equal to zero. This will ensure rotational equilibrium

Newton's Third Law of Action and Equilibrium

As per Newton's third law of motion, for every action there is an equal and opposite reaction along the same line of action as the original force. This is explained in detail in the below figure-2.

What is Structural Equilibrium? | Translational & Rotational equilibrium

Every element part of a structural system will have reactions that will contribute to the equilibrium of the whole system.

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This is a center to bring up and collect all bits of knowledge and technologies flourished and flourishing to reach out for those who wish to acquire knowledge in a broader way. I am a structural engineer by profession and would like to share all information I have acquired all these years till date. This site also aims in researching new topics, works on your questionnaires and fill it up with good facts and information.

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