本研究主要是以新型高拉力鋼筋與高強度混凝土材料所製成之New RC T形懸臂梁(a/d=2.4)試體，利用反覆加載實驗來探討存有預鑄施工縫的試體與一體成形的試體在耐震行為上的差異。其中，試體主筋使用#8高拉力SD685MPa螺紋節鋼筋搭配高強度混凝土(60MPa)，梁箍筋按規範ACI 318-11耐震設計規定作配置，採用#4高拉力SD785MPa竹節鋼筋。文中除了探討預鑄施工縫在耐震行為影響外，亦探討目前規範與學者之交接面剪應力經驗式在耐震影響之適用性。 由實驗結果得知，存有施工縫的T形梁試體，其整體耐震行為與單一澆鑄T形梁試體相似；但在極限狀態負彎矩有效版寬(即版筋貢獻)調查，存有施工縫的T形梁有效版寬反而大於單一澆鑄試體1.4倍，其結果與先前普通鋼筋混凝土T形懸臂梁耐震測試[2]一樣。各國學者提出的經驗式[7、8、10]與實驗結果相似，而規範經驗式[3、4、5、6]則較保守。 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.
