Nonlinear Hysteresis Behavior of Precast/Prestressed Concrete Member

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Prestressed Concrete (PC) members subjected to cyclic bending and shear shows non-linear hysteresis behavior characterized with (1) S-shape loops with origin-oriented unloading branch, and (2) smaller capacity to dissipate hysteretic energy than ordianry reinforced concrete (RC) members. These characteristics seems to be influenced by many factors including amount of prestressing steel, shear force level and bond-slip of between concrete and prestressing steel. The objective of this study is to identify the reason of the characteristics by tests and analyses.In the first year, six prestressing beam specimens were loaded to failure subjected to pure cyclic bending, parameter of which included bond-slip capacity of prestressing steel. In the next year, three 1/2.7 scale exterior beam column joint specimens were loaded to failure to investigate the effect of the slab and shear-to-span ratioin PC members. In the last year, two interior and two exterior beam column joint subassemblies with prestressing in beam were tested to investigate the effect of prestress on the strength and deformation of beam-column connections.From those test results, it is revealed that the strength, stiffness and shape of hysteresis loop were significantly affected by the bond-slip characteristics of prestressing steel. Hence, non-linear cyclic flexural analysis with Bernouri's assumption was extended to be applicable to the PC members taking into account the effect of constitutive relation of bond-slipl. The reliability of the analytical method is examined using the test data.