鋼骨鋼筋混凝土(SRC)深梁試驗與剪力強度研究

Abstract

本研究藉由一系列包覆型鋼骨鋼筋混凝土（Steel Reinforced Concrete, SRC）深梁（Deep Beam）試驗，以探討SRC深梁在單向載重作用下之力學行為。並根據SRC深梁之實驗結果及在實驗過程中觀察到的力學行為與破壞模式，提出一個針對SRC深梁抗剪強度的評估新方法。 根據實驗觀察，本研究發現SRC深梁與RC深梁均會發生繫拱作用（Tie-Arch Action）。但是由於鋼骨的存在，SRC深梁僅有在鋼骨翼緣左右兩側之混凝土因受到繫拱作用而被壓碎，此現象與RC深梁之破壞情形有明顯的不同。此外，本研究亦發現在鋼骨翼板或腹板加銲剪力釘對於SRC深梁之抗剪強度並無明顯之貢獻。不過，在SRC深梁之韌性改善方面，本研究發現在鋼骨腹板加銲剪力釘或配置適當的剪力筋有助於延後腹板在受到強大外力作用下發生局部挫屈現象，使得SRC深梁具有較佳的韌性。 本研究建議之SRC深梁剪力強度評估新方法採用強度疊加之概念，該法結合美國AISC-LRFD規範對鋼梁強度之計算法與有關RC深梁之繫拱模型（Strut-and-Tie Model）對剪力強度之預測法。經由與SRC深梁之試驗結果比較得知，本研究建議的方法將可以合理的預測SRC深梁的抗剪強度。

A series steel reinforced concrete（SRC）specimens were tested with vertical monotonic load to study the mechanical behavior of SRC deep beams. In addition, a new method for determining the shear strength of steel reinforced concrete deep beam is proposed in this paper. Experimental results show that the shear capacity of SRC and RC deep beams are mainly controlled by the tie-arch action. However, due to the existence of steel shape in SRC deep beams, the crack pattern and failure mode are significantly different from those an ordinary RC deep beam. Test results also reveal that using of shear stud on the steel flange and web has little improvement on the ultimate shear strength. However, the application of shear reinforcement and shear stud on the steel web is found to be helpful for improving the ductility of SRC deep beams. The proposed method is based on the concept of strength superposition. The component materials strength are determined by using the AISC-LRFD specification（1993）for steel portion and the strut-and-tie concept for RC portion. By comparing the proposed method with the test results available from the literature, it is found that the proposed method is capable of predicting the shear strength of steel reinforced concrete deep beams with sufficient accuracy.