Numerical and Experimental Analysis of CFRP Strengthened Unbonded Post-tensioned Indeterminate I-Beams Consisting UHSSCC

The prestressed concrete was first introduced to predominance the concrete tension weakness and use the concrete compressive capacity to improve the serviceability state of such members. In these members the need of utilization of concrete with higher strength due to their lower prestressed losses have been recognized. There are very little investigations on prestressed members consisting of ultra high strngthed concrete, UHSC (concret with a compressive strength higher than 80MPa). This has led to concrete constructions with posttensioned ultra-high strength self-consolidating concrete, UHSSCC, which is relatively new category of concrete. Over the last two decades, numerous studies (experimentally and theoretically) have been conducted on the behavior of simply-supported and continuous reinforced concrete (RC) beams, that were strengthened with fiber reinforced polymer (FRP) composites. This paper investigates the finite element methods for modeling the unbounded posttensioned concrete beams. This objective is achieved by conducting flexural testing of unbonded post-tensioned UHSSCC continuous (full scale) I-beam strengthened by carbon fiber reinforced polymer, CFRP sheets in sagging and hogging regions. The numerical results was compared with experimental results in terms of crack pattern and different ductility indexes (which are significant is seismic zones) and the following results were drawn: Considering the optimized mesh density and the sensitivity analysis to dilation angle, a dilation angle of 36 yielded the best results comparing the numerical and experimental results. Despite the the application of unbounded tendon along the two span of the beam, the numerical and experimental crack pattern at different load steps were reasonably matched.