Il rafforzamento dei pilastri in c.a. mediante il sistema CAM

One of the main reasons of weakness of existing R/C structures with respect to seismic actions is often to be ascribed to the low strength and ductility of columns. As known, ductility improves considerably if concrete is laterally confined. Such confinement is traditionally realised by angles and brackets, and implies increase of dimension and difficulties of implementation. Their effectiveness is also conditioned by a correct implementation, to obtain a perfect contact of the angles with the existing concrete as well as a pre-strain through preheating of the cross stiffening brackets. The CAM system (Active Confinement of Manufacts) represents an effective alternative solution. It is implemented by using angles with smoothed edge and high strength steel ribbons 0.8-1.0 mm thick, which are pre-tensioned to give a beneficial pre-compression state in concrete and to be immediately effective when increasing loads. Its total thickness of being of the order of 6-8 mm, the confining device can be easily contained within the normal plaster. The effectiveness of the CAM system for the confinement of R/C concrete columns has been verified through several experimental compression tests on 34 squared section columns with 25 cm side, by evaluating the improvement of strength and ductility. In this paper the CAM strengthening system is presented, along with the main results of the experimental tests.