In the majority of recent studies the dynamic behaviour of significant elements in the system has been overlooked. Furthermore, current codes are unable to suggest clear and realistic approaches. Therefore a proven method of analysis needs to be undertaken to provide better predict the vibration characteristics in composite steel-concrete beam systems. This research takes advantage of the finite element package ABAQUS to describe a study of the dynamic behaviour of isolated and coupled composite steel- concrete beam systems under free vibration analysis. This report also includes several chapters describing theoretical investigations, computer modelling, evaluation of the results, and recommendations for further study. The first six isolated beams of different lengths are simulated and analysed, and then 24 coupled composite beams are simulated and analysed by considering different length girders at differing distances. The purpose of this study is to derive a theoretical and analytical analysis to predict realistic concepts, and present an active mode in composite steel-concrete beam systems instead of the combined modes.