Structural dynamics

Ans 1) Dynamic analysis of structures considers dynamic loads acting on the structure such as wind and earthquake which varies with time. Those loads are sudden & does not follow a constant pattern & vary with time. In dynamic analysis along with stiffness matrix, mass matrix and damping matrix is also included. Here the motion of the structure is considered. Static analysis of structure considers static loads acting on the structure such as dead,live load which does not vary with time and are not considered to be sudden. In static analysis stiffness matrix alone is considered & the inertial forces are not considered. here the motion of the structure is not considered.

Ans 2) Elastic behaviour:- Elastic behaviour can be defined as the ability of the components to return to its original shape when an application of external loading is removed. The explanation is that any component under loading like compression or tension loses its original shape and tends act according to the load and when the load is removed the component restores to its original shape when the loading is removed.

Inelastic behaviour:- Inealstic behaviour of materials is defined as the inabilities of the materials to return to its original shape when the load is removed & tend to be in the deformed shape. The material undergone deformation acts opposite to elastic behaviour.

Plastic behaviour:- The property of the material which has the deformed shape and permanent strain in it when the loading is removed is called the plastic behaviour of structure. The plastic behaviour of the structure occurs beyond the yield point of the structure and the deformation is irreversible even when the loading is removed.

Non-linear Inelastic behaviour:- When large deformations occur at the material, the force displacement relationship of the material becomes non linear. Force corresponding to displacement is not single valued in non linear behaviour and depends on the history of deformations of the material.