Influence of the initial prestressing on the crack resistance of the self-stressed members reinforced with steel and FRP bars

Abstract

Fiber reinforced polymer(FRP) bars are widely utilized in the civil engineering practice and characterized by the number of advantages, among them are the following: high strength-to-density ratio; absence of corrosion; resistance to the negative influence of the different aggressive mediums. Nevertheless, a wide practical application of such a bars finds an embarrassment because of the law modulus of elasticity (in the diapason from 30 GPa to 60 GPa), that in its turn lead to the development of the excessive crack opening as well as deflections under the loading. To enhance structural performance of the FRP reinforced concrete members, pretensioning of FRP bars can be considered as a good option. Opposite to the concrete members mechanical pretensioning, physico-chemical method of bars pretensioning based on the self-stressing concrete utilizing is considered. Influence of the controlled initial stress-strain state obtained during early age concrete expansion on the mechanical resistance of the self-stressed concrete members reinforced with both steel and FRP bars was studied. Comparison of the prestressing effectiveness of the self-stressing concrete members with steel and FRP bars was performed. Proposition for effective utilizing of the FRP bars in the self-stressed concrete members was formulated based on results of the presented investigation.