根據ACI318-02，短梁是以剪力跨度a及有效深度d之比值作定義，當a/d 2.5則為短梁，反之則為長梁。對於其分析方法，規範是建議以壓拉桿模式來分析短梁，長梁以斷面剪力評估式作分析。本研究主要探討以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形梁作分析，藉以比較T形梁與矩形梁在分析上有何不同之處。 本實驗之試體針對不同之剪力跨深比a/d作設計，矩形梁與T形梁各5根試體，在剪力區內為無箍筋之設計。由實驗得知，無論矩形梁或T形梁，以壓拉桿模式作為短梁之預測剪力分析，其結果還算準確。由結果來看，T形梁在分析上與矩形梁最大不同處，在於T形梁多出了翼版之部分，因此在斷面分析時是考慮翼版寬度，並非梁腹寬度。此外，本實驗所採用的分析模式中，也探討了不同的壓桿軟化模式之影響，由結果得知，以本文所建立之模式做為短梁分析應屬合理。 According to ACI318-02, the behavior of deep beam is defined as the ratio of shear span to effective depth a/d 2.5. Strut-and-tie model analytical method can be adopted to the shear strength evaluation of the deep beams. The main purpose of the research is to see the validity of strut-and-tie model applied to analysis of rectangular and T-sectional beams. The comparison of analytical results between rectangular and T-section beams are discussed. Experimental works were made on testing five rectangle and five T-sectional RC beams, where no stirrup was used. Specimens were controlled by different shear span ratio, a/d. From the experimental result, the proposed strut-and-tie model for analyzing T-sectional and rectangle beams is fairly accurate. The largest difference in analyzing is that T-sectional beams have offered more discrepancy such as flange parts. However, the proposed model is more rational than previous researchers adopted using different softened strut-concrete behaviors.
