Strengthening of reinforced concrete columns using FRP

Upotreba polimera armiranih vlaknima (PAV-a) kao materijala u građevinarstvu je relativno nova (istražuje se i koristi zadnjih dvadeset godina), te za sada ima ograničeno područje primjene. U ovom radu obrađena je upotreba PAV-a za pojačanja postojećih armiranobetonskih stupova, kao alternativa tradicionalnom pojačanju povećanjem presjeka izvedbom armiranobetonske ili čelične obloge. Rad se sastoji od dva dijela. U prvom dijelu dan je kratak opis osnovnih karakteristika PAV-a, mehaničkih svojstava i tehnika izvedbe. U drugom dijelu rada obrađeno je pojačanje armiranobetonskih stupova izvana nalijepljenim oblogama od PAV-a. Analizirano je (i) povećanje nosivosti na osnu tlačnu silu uslijed ovijanja betona i (ii) povećanje posmične nosivosti. Razmatrani su stupovi kružnog, kvadratnog i pravokutnog poprečnog presjeka.The use of fibre reinforced polymers (FRP) as building materials is relatively new; it has been in research and use for the last twenty years and so far has a limited application. In this paper strengthening of concrete columns by means of externally bonded FRP is analysed as an alternative to traditional strengthening made as cross-sectional increase by reinforced concrete or steel jacketing. The paper is divided into two parts. In the first part a brief overview of basic features of FRP is given, together with mechanical properties and application techniques. In the second part strengthening of reinforced concrete columns by means of externally wrapped FRP jackets is presented. Increase in (i) axial bearing capacity due to concrete confinement and (ii) shear strength capacity has been analysed on circular, square and rectangular cross-sections