根據ACI 318–02，以剪力跨度 a 與梁總深 h 之比值﹙a / h﹚來區分，當a / h ≦ 2.0時稱之為短梁。亦可使用剪力跨度 a 與有效深度 d 之比值﹙a / d﹚來區分，當a / d ≦ 2.5時稱之為短梁，反之則為長梁。對於剪力強度之分析方法，規範是建議以壓拉桿模式來分析短梁，以傳統剪力經驗公式來分析長梁。本研究主要探討以三種壓拉桿模式作為分析短梁之適用性，除了應用於矩形梁外，另外也對T型梁作分析，藉以比較T型梁與矩形梁在分析上有何不同之處。 本研究之試體針對不同剪力跨深比﹙a / d﹚，分別施作8根矩形梁與10根T型梁。試體剪力筋配置方式分為無剪力筋和依規範規定兩種。由實驗結果得知，無論有無配置剪力筋之矩形短梁或T型短梁，使用軟化壓拉桿模式分析剪力強度，其結果有一準確度。另外由實驗結果亦可發現在預測剪力強度時，應以實際斷面形式去做分析，若以矩形斷面代替，則分析結果會較不準確。 According to ACI 318-02, the RC beam with a / h ≦ 2.0 or a / d ≦ 2.5 so called as deep beams. The code suggested that the shear strength of deep beams be calculated using strut and tie model, and using the traditional experimental formula for the shear strength of normal-span beam. This study discusses the effect of three types of strut and tie model methods to analyze the tested deep beams. Meanwhile, these models applied to the prediction on not only the rectangular sectional beams but also T-sectional beams. Experiment specimens were made according to different ratios of a / d. That is, 8 rectangular beams and 10 T-beams were provided for testing The transverse reinforcement has two type of arrangement. One has no transverse reinforcement and the other has transverse and horizontal shear reinforcement designed according to ACI code. The experimental result shoes that prediction on rectangular beam and T-beams using softened strut and tie model is more accurate It also was found that the flanges contributed to some amount of shear strength of deep beams. The prediction results might not be accurate, if engineers did not consider the contribution of slab flanges for shear strength evaluation.
