Fundamental Research on New Technologies derived from Bond Control of Tendons in pre-stressed Concrete Members

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Considering resources and environment in the near future globe, both to be stock and to be flow will be demanded for architectures. This study which aim to investigate new technologies and design methods suitable for performance design of concrete structures, has following two objectives. (a) Development of reuse pre-cast concrete structural members with high self-centering force and superior energy dissipation. (b) Estimations of influence of bond characteristics of prestressing tendons on mechanical properties of prestressed concrete structures. Following main conclusions are obtained.1) A separable joint between pre-cast concrete brocks are developed newly. Mechanical characteristics of the joint with various assembling stress, strength of joint materials, depth of joints and so on were investigated through uni-shear test. The test results show that the joint has very useful separability and practical shear strength.2) Cyclic reversal loading tests on prestressed concrete beams consisted of concrete blocks and assembled by unbond prestressing tendons were carried out. Test results reveal that the beam can get superior energy dissipation by the use of additional low strength reinforcing bars attached on the beam sides as a damper device and shows reusability of concrete blocks owing to only slight damages observed in the first concrete block adjacent to column stab, even though under severe deflection of the beam.3) Analytical studies on equivalent damping factor of load-deformation relations of prestressed concrete beams subjected to cyclic reversal load were conducted using divided element method. From results of the analysis considering factors such as bond characteristics, amount and location of prestressing tendons in the beam sections, an equation to estimate equivalent damping factor which predicts experimental results with practical accuracy are derived.