Structure mechanics 

  Structure mechanics is the branch of mechanics that deals with force and motion of structures systems. It's the computation of deformation,deflection and internal force of stresses within structure for the evaluation of existing structures.

 Approaches of structural analysis the two basis approaches of structural analysis are as follows:

(a)Force method

(b)Displacement method

(a)Force method

          In this method the number of independent unknown forces is found and is compared with the number of independent equation of static equilibrium that can be written involving these unknown force. If the number of unknown is equal to number of independent equation the unknown forces can be directly determined. But if the number of unknown forces in excess to the equilibrium equations are designed  as redundant forces and are assumed to be removed as restraints to obtain a statically determinate resudual structure called primary structure.

(b)Displacement method

       In this method the independent unknown displacement components involved in the structure are estimated and these are considered as the unknown to be found. The inertial force in the structure are than expressed in terms of these unknown displacement using the stress displacement relations.for each unknown displacement components a corresponding equilibrium is written in terms of known external forces and unknown inertial forces which are expressed in terms of the displacement.these equations are solved to find the unknown displacement.