Stress Loss Of Prestressed Concrete Beams Reinforced With Carbon Fiber

As a high-performance carbon fiber materials have been widely used inreinforcement. But experiments showed that traditional methods can not play pastinghigh strength carbon fiber material and reinforcement effect is very limited. Prestressedreinforcement technology is an active reinforcement technology, not only can makehigh-strength carbon fiber material to play, and can greatly improve the reinforcementeffect. Up to now, there have been a variety of domestic and prestressed carbon fiberreinforcement technology, is currently strengthening technology research focus.The use of prestressed carbon fiber reinforced research necessarily related to theprestressing losses. Current research on prestressed carbon fiber material forprestressed CFRP major losses and carbon fiber research, but the level of literaturefound prestressed carbon fiber sheet relative to previous studies of carbon fibermaterial is low (generally less than1000Mpa), while the prestressing loss rate is stillhigh (10%to30%). The research team developed a hinged anchor tensionedprestressed anchor carbon fiber technology, research for prestressing losses are basedon the process there are some deficiencies, some studies still blank. To this end, thethesis of prestressed anchor prestressing loss hinged carbon fiber process carried outsystematic experimental studies and theoretical analysis, the main results obtained areas follows:①Through a large proportion of T beam prestressed reinforcement testcomponents tested in single and double carbon fiber prestressed tension stress process,prestressed put sheets and long-term losses, the total loss rates are lower thanprestressed3%, of which a single layer of carbon fiber (50mm×2mm) at high levelsof pre-stressed (2079MPa), the prestressing loss rate of1.6%. These test resultsshowed that the hinge-based waveform anchor tensioned prestressed carbon fibertechnology to its high efficiency, low stress losses, technology is relatively advanced.②In this paper, the reinforcement process, the role of torque when tighteningbolts and carbon fiber lifting effect can increase the amount of carbon fiber tensilestress, to make up for their loss of prestress, carbon fiber has the potential to exceed thefinal effective prestressing tensile stress of the first carbon fiber paper which is acharacteristic of the process of prestressing. ③Prestressed deduced formulas increment when torque is applied and jackingcarbon fiber to provide reference for practical engineering calculations incrementalprestressing two parts.④Refer to “reinforced concrete and prestressed concrete highway bridge designspecifications” in the post-tensioned loss classification and calculation methods, inorder to summarize and derive a prestressing loss hinge anchor tensioning of carbonfiber main factors: Anchoring system deformation, elastic concrete compression stressrelaxation prestressed carbon fiber, concrete shrinkage and creep, and the calculationformula and effective method for the calculation of prestressed prestressing losses.These studies show that the use of prestressed anchor tensioning process hingedcarbon fiber, easy tensioning operation, the retraction small anchor, reliable anchoring,high operating efficiency. Considering various factors, long-term loss of concretestructures can be approximated take3%of the initial tensile stress to simplify theestimate of the total prestressing losses.