The Effects Of Rotational Inertia On The Response Of Dynamically Loaded Structures

ABSTRACT

Engineering structures subjected to dynamic loading exhibit vibration motions.

These vibrations induce accelerations on the structures and their component

parts. The accelerations in turn generate inertia forces that propagate the

vibrations and significantly affect the response of the structures and their

components parts to external loading. This cyclic cause and effect situation result

in randomly oriented and time-dependent displacements as the basic response

criteria of structures that are subjected to dynamic perturbations. Researches

have shown that translational and rotational inertia are exhibited in the cause of

these vibrations. Consequently, it was concluded that translational and rotational

inertia are generated in structures under dynamic loading. However, translational

inertia has, over time, been the subject of research in dynamic analysis of

engineering structures. It is often the only inertia force considered in analysis,

design and determination of the important response criteria of structures

operating in dynamic environments. Indeed the effects of all significant inertia

forces should be considered in the analysis and design of dynamically loaded

structures. This is to ensure that the results to be obtained will truly simulate real

conditions. This work seeks to investigate the effects of rotational inertia on the

response criteria of structures subjected to dynamic perturbations. The results

obtained from the numerical solutions of the equations of motion developed

show that some important fundamental natural frequencies are obtained with

the consideration of rotational inertia. The solution of the equations of motion

also show that there are significant increases in the internal stress distributions

evaluated when rotational inertia is taken into consideration. It is evident;

therefore, that rotational inertia can no longer be ignored in the analysis of

dynamically loaded structures because the internal stress distributions and other

response criteria are significantly affected by rotational inertia forces