Nonlinear Full Range Hysteretic Analysis Of Unbonded Partially Prestressed Concrete Beams

Unbonded partially prestressed concrete structure is more widely applied in theconstruction projects because of its advantages, such as constructing conveniently andexcellent performance. However, the analysis of unbonded partially prestressedconcrete structures is much more complicated due to the relative slippage betweenunbonded tendons and concrete. In this thesis, a reasonable method, which is based onthe moment-curvature analysis and the deformed coordination, is proposed for thenonlinear full range hysteretic analysis of unbonded partially prestressed concretebeams. Furthermore, the hysteretic characteristic, ductility and energy dissipationcapacity of unbonded partially prestressed concrete beams are analyzed. This thesisfocuses on the following details:1. The development history of prestressed concrete is introduced separately, aswell as the research achievement and the present situation of unbonded prestressedconcrete beams. And, the necessity and meaning of putting forth a simple andreasonable method which is based on the moment-curvature analysis and the deformedcoordination for the nonlinear full range hysteretic analysis of unbonded partiallyprestressed concrete beams are explained.2. Based on research productions that have been obtained, constitutive relationsunder cyclic loadings of every materials are selected. After having an in-depthanalysis on the mechanical characteristics of unbonded partially pretressed concretebeams, some key steps, such as unit division, idealization of plastically deformingarea, application of interpolation method and so on, are explained in detail. Anonlinear full range hysteretic analysis method is put forward and a MATLABprogram is developed.3. On the base of summarizing the general characteristics of hysterestic curve oftested beams, the hysteresis mechanism of unbonded partially prestressed concretebeams is analyzed and the calculating formulas of feature points on the skeleton curveis suggested. Through comparing and analyzing, the calculated results coincide wellwith the testing results. The correctness and reasonability of the program is varified.4. Another similar test is analyzed by the MATLAB program. And the testingresult agrees well with the result calculated. Then a series of model beams prestressedwith unbonded tendons, which have different concrete strength, integrated reinforcement index0and prestressed degree, are simulated. According to thecalculated hysteretic loops and ductility index, a reasonable integrated reinforcementindex0which meets the requirement of ductility is suggested. The researchprovides a reference for the aseismic design of unbonded partially prestressedconcrete beams.