| Summary: | 碩士 === 國立中央大學 === 土木工程學系 === 101 === The main objective of the study was to investigate the effect of precast cold joint formed between slab underside and beam web on the seismic behavior of New RC cantilever T-section beams. Two RC short cantilever T-beams (a/d=2.4) were fabricated using ultra-high-strength steel reinforcement (SD685MPa #8 screwed type for main bars, and SD785MPa #4 deformed type for stirrups) and 60MPa high strength concrete. One beam with cold joint and the other beam without cold joint were tested under cyclic loading to observe the difference of seismic performance due to the formation of precast cold joint. Meanwhile, the assess results from empirical equations of frictional shear provided by design codes and previous researches were compared with the test results.
According to experimental results, the overall seismic behavior of the New RC T-beam with precast cold joint resembled the T-beam cast monolithically. However, the effective slab width in negative moment (i.e. the contribution of slab bars) for the beam with cold joint is 1.4 times wider than that for the beam cast monolithically, which is the same conclusion as obtained from the experimental study on the normal RC cantilever T-beams[2]. The values predicted from the equations proposed by the previous researchers [7、8、10] agreed the experimental results well. The assessment attained from code’s equations [3、4、5、6] showed conservative as expected.
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