Ultimate Unbonded Tendon Stress in CFRP Strengthened Post-Tensioned Indeterminate I-Beams Cast with HSCs

Based on the bending experiment for two-span continuous post-tension beams with unbounded tendons and externally applied cfrp sheets, the analysis of the stress increment of unbonded tendons is monitored in the loading process. since self-compacting concrete (scc) is a suitable innovation,, understanding the implementation of this type of concrete on the ultimate unbonded tendon stress is critical. for these aims, results of four continuous un-bonded post-tensioned i-beams in two groups were cast and monitored by electrical strain gauges andare presented here. in the first group, the beams (upn1-12, supn1-12) consisted of high strength normal concrete (hsnc), while in the second group (ups1-12, sups1-12) high strength self-compacting concrete (hsscc) were tested. the beams are made which are compared with the theory proposed by different codes, and a preliminary modification is given for each code equation. the results of standard error of estimate sy/x , indicates that for two types of hscs (strengthened and non-strengthened beams), the aci 318-2011 provides better estimates than aashto-2010 model, whereas this model provides better estimates as compared tobs 8110-97.comparison of increase in experimental ultimate tendon stress of beams indicates that the increase in tendon stress at ultimate state in strengthened beams is lower than that in non-strengthened beams cast with hscs.