Particularities of FRP structural rehabilitation of concrete columns in frames

Abstract

Columns, in general, and reinforced concrete (RC) columns, in particular, are barely used as individual elements. In most of the structures, columns are but a part of the designing problem. The complex state of combined internal efforts makes the design of structural columns a very laborious task for the engineers.
When rehabilitation interventions are required, the problem becomes even more difficult. Lately, the use of Fibre Reinforced Polymer (FRP) composite materials in retrofitting the columns have shown to significantly improve the performance of RC columns as parts of frames.
The most usual problems related to the topic are the insufficient lap lengths in reinforcement splices, spalling of concrete resulting in premature loss of anchorage of the reinforcement bars and possible sudden/brittle failure mechanisms, insufficient transversal reinforcement leading to poor resistance in shear.
The present paper tries to point out the main aspects related to columns behaviors in shear, to make a comparative discussion of existing models for columns in shear and testing procedures. The principal methods of enhancing the shear strength of structural columns using FRP composite materials are also to be presented.