高強度混凝土含圓形開孔深梁之剪力強度

Shear Strength of High-Strength Concrete Deep Beams with Circular Openings

本研究共製作 9 支高強度混凝土含圓形開孔深梁進行試驗，並以 Kong and Sharp之經驗公式及 Tan et al.之壓-拉桿分析模型做為分析工具，來預測 高強度混凝土含圓形開孔深梁之剪力強度。研究結果顯示，在距圓開孔上方 25mm 處配置 2#4 水平鋼筋，以提供足夠的水平拉力，有助於深梁上部剪力傳 遞路徑貢獻其抗剪強度。故而在開孔上方設置水平鋼筋，對於含圓形開孔深梁 之設計確實非常重要。一般而言，深梁之剪力強度會隨著開孔直徑之增加而降 低。開孔位置度較高之深梁，其抗剪強度相對較低。本研究建議設計時應以 Kong and Sharp [1]之經驗公式，來計算高強度混凝土含圓形開孔深梁之剪力強 度以確保安全。

In this study, nine high-strength concrete deep beams with circular openings were tested. The empirical formula of Kong and Sharp [1] and the strut-and-tie model of Tan et al. [2] were used for predicting the shear strength of high-strength concrete deep beams with circular openings. The results show that the 2-#4 horizontal steel bar is placed 25 mm above the circular openings to provide sufficient horizontal tensile force, which helps the shear strength of deep beams transferred by the upper shear transfer path can fully develop. The arrangement of the horizontal steel bars above the openings is important for the design of the deep beams with circular openings. In general, the shear strength of deep beams decreases as the diameter of openings increases. Deep beams with higher location of the openings, the shear strength is relatively low. This study recommends the empirical formula of Kong and Sharp (1977) to calculate the shear strength of high-strength concrete deep beams with circular openings to ensure safety.