CONFINEMENT EFFECT IN INCREASING THE COMPRESSIVE STRENGTH OF COLUMNS

Confinement for concrete which contains compressive tension on the concrete element perpendicular to the loading direction, is a popular technique that is commonly used to improve the strength and ductility of concrete members . nowadays, confining the columns, not only as a method of repairing, but also as a retrofitting methodology has been considerably expanded. Conventional methods of confinement of concrete are tights , steel sheets and fibers FRP. But between this type of confinement , polymer fibers because of their distinctive features, have been most discussed and tested. The main endeavoure of this paper is to to scrutinize The effects of confinement on compressive strength of columns. In this article it is stated that the active confinement due to initial lateral compresion loading on concrete core, make improvment at column behaviour and will increase its strength And this function to avoid the column cracks is really effective. in this paper, some researches with the issue of increasing the compressive strength of columns are mentioned. during a test of 14 cylindrical and cubic specimens enclosed with carbon and glass fiber, has been demonstrated that the compressive strength of columns with confinement has really increased And the effects of confinement with polymer fibers on cubic columns was less than cylindrical columns under compressive load And in another study the behavior of CFRP wrapped concrete columns is mentioned , Including 9 concrete column with a square cross-section with various amount of confined wrapping for each column, the compressive load carrying strength was increased.