Numerical assessment of continuous prestressed NSC and HSC members with external CFRP tendons

Abstract

Carbon fiber reinforced polymer (CFRP) is a promising material for prestressing tendons. This study assesses the structural performance of continuous prestressed members with external CFRP tendons, focusing on the effect of using high-strength concrete (HSC) instead of normal-strength concrete (NSC). A nonlinear model is introduced and numerical tests are then carried out. Three concrete cylinder compressive strengths of 40, 60 and 90 MPa are used. The area of external CFRP tendons varies from 200 to 1700 mm2. The results show that the effect of using HSC instead of NSC heavily depends on the area of external CFRP tendons. In general, HSC members with external CFRP tendons exhibits considerably different response characteristics from those of NSC ones, including cracking, deformations, tendon and rebar stresses, neutral axis depths and so on. The concrete grade influence on moment redistribution is found to be negligible, provided that the members demonstrate favorable ductility. The rules in ACI 318-14 concerning the unbonded tendon stress and the redistribution of moments are evaluated.