Research On Seismic Performance Of Unbonded Prestressed Concrete Beams

Due to the advantages of simple construction, small friction and no reserved channels, the unbonded prestressed concrete structures have been widely used. However, the analysis of unbonded prestressed concrete structures are much more complicated than that of bonded prestressed concrete structures, because of the unbonded characteristics between prestressing tendons and surrounding concrete. It is necessary to analyze the seismic performance of unbonded prestressed concrete structures for the breadth and complexity of earthquake. Moment-curvature hysteretic models are proposed based on hysteresis curves obtained from cyclic loading tests, the ductility and energy dissipation are also been considered. This paper focuses on the following details:(1)In review of existing experimental and theoretical researches about moment-curvature hysteretic models, this paper noted its advantages and deficiency, also, put forward the need to establish moment-curvature hysteretic models of unbonded prestressed concrete beams.(2)This paper summerized the existing experimental researches about unbonded prestressed concrete structures, especially the experiment about the source of date in this paper, including its basic situation, experiment phenomena and results.(3)Based on the test results of unbonded prestressed concrete beams under low cyclic loading, formulations for determining of the related pivot pinching points and the hysteretic rules of Moment-curvature hysteretic models are proposed according to statistical evaluations, which was incorporated into the MATLAB model to simulate unbonded prestressed concrete members. Studies indicate that the analytical results agree well with the test results. Part of the beams were analyzed based on the finite element method at the same time.(4)Ductility and energy dissipation capacity were analyzed with different methods based on the experiment and the results were compared with the reinforced concrete and bonded prestressed concrete beams. The influence of various parameters on the ductility and energy dissipation capacity of unbonded prestressed concrete beams under seismic loading is presented.