MODAL DAMPING ASSESSMENT IN CRACKED REINFORCED CONCRETE BEAMS

In the present work a fundamental study of modal damping in cracked reinforced concrete beams based on finite element modelling is performed. The objective is to improve the understanding of the damping evolution in the case of a cracked reinforced concrete beam. The study is performed on a reinforced concrete beam and is based on the energy balance approach. In the model, two degradation processes in the concrete matrix are considered: the decrease of rigidity in the cracked section and the friction effects due to relative motion of the crack edges. The total damping of the beam is evaluated using the twophase model which is already used for polymeric composite materials and is derived on the one hand from the damping coefficients of the steel reinforcement and of the concrete matrix and on the other hand from the strain energy distribution between the two components of the reinforced concrete beam. The model shows that the decrease of rigidity in the concrete matrix apparently leads to a decrease of the total damping of the reinforced concrete beam while the later is apparently increased by the friction effect. This study shows that damping in reinforced concrete structures is a complex phenomenon, depending on the actual status of the structure, and it is affected by two mechanisms that lead to opposite damping evolutions.

• INTRODUCTION

• DAMPING IN RC ELEMENTS: THEORETICAL ASPECTS

• FINITE ELEMENT MODELLING

• RESULTS AND DISCUSSION

• CONCLUSIONS

• ACKNOWLEDGEMENTS

• REFERENCES