SUMMARY

There has been an increased interest in recent years for everything related to rehabilitation and strengthening of reinforced concrete structures. The main reason for the development of this civil engineering field is the unavoidable aging of the existing structures, but also due to other economic and environmental factors, or the changes of regulations caused by a better knowledge of the medium.
The present research work arises from the necessity to extend the knowledge about the behaviour of reinforced concrete columns strengthened with steel angles and strips, because this is one of the most popular strengthening method in our country.
The study has begun doing a scientific literature research related to the state of the art of:
* Strengthening of reinforced concrete columns.
* Influence of the column confinement in the increase of column compressive stress.
It has been planned and developed experimental tests that allow to know and to analyze the behaviour of the strengthened columns considering the different variables that take place in its configuration.
After the analysis of the experimental results, that  allows the development  of a conceptual model of behaviour,  and the comparison with existing formulations, the necessity of the elaboration of  better simplified calculation methods is confirmed.
Simplified methods for the analysis of strengthened columns with steel angles and steel strips valid for its application in the design and project of rehabilitation and strengthening of reinforced concrete structures, have been proposed.
Finally the viability of the application of the proposed simplified methods has been checked. In this way, the state of knowledge of the behaviour of strengthened columns with steel angles and steel strips has been extended.