Experimental Research On The Flexure Performance Of Unbonded Prestressed Steel Reinforced Concrete Beams

Unbonded prestressed steel reinforced concrete is a new kind of structure systemwhich combines the advantage of unbonded prestressed reinforced concrete and steelreinforced concrete. It has great development future in large-span, heavy-loaded,high-rise and super high-rise buildings. At present, the research of unbondedprestressed steel reinforced concrete has just began, so this paper makes static loadtests on five unbonded prestressed steel reinforced concrete beams, one unbondedprestressed reinforced concrete beam and one steel reinforced concrete beam, and thethesis makes an analysis of the lfexure performance, bearing capacity of normalsection and ductility of the beams. This paper focuses on the following details:(1)The characteristic and research status of unbonded prestressed steelreinforced concrete, unbonded prestressed reinforced concrete and steel reinforcedconcrete have been introduced separately, as well as the calculation methods of thestress of unbonded prestressed tendons. Furthermore, the necessity and meaning ofthe research of unbonded prestressed steel reinforced concrete structure have beenexplained.(2)The static load tests of seven beams have been completed. In the tests, someimportant data such as the deformation, strain, curvature and the stress increment ofunbonded prestressed tendons have been measured, and the crack development andfailure models have been observed. In addition, the moment-delfection curves, thestress increment of unbonded prestressed tendons, the compression strain distributionof concrete, the delfection ductility and curvature ductility of the beams have beenanalyzed and some useful conclusions have been drawn.(3)The calculation formula of unbonded prestressed tendons has been come upby means of linear regression of the test data. The bearing capacities of the unbondedprestressed reinforced concrete beam and the steel reinforced concrete beam havebeen calculated according to the relative standards, and the calculation methods of thebearing capacity of unbonded prestressed steel reinforced concrete beams have beenderived on the basis of basic assumptions. The calculation results match well with thetest results.(4)Considering the nonlinearity of materials, a MATLAB ifnite element analysisprogram has been made. By means of adding deformation increasingly, the moment-curvature curves of unbonded prestressed steel reinforced concrete beamsunder the whole process can be obtained. The calculation results match well with themoment-curvature curves of the tests.