Simplified Strut and Tie Model for Deep Reinforce Concrete Beam

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Prach Amornpinyo
Jaruek Teerawon


Experimental program comprised the testing to failure of 9 deep reinforced concrete (RC) beams designed by strut and tie model (STM) according to Appendix A of ACI 318-11. The tested specimens were designed with various shear span-to-effective depth ratios (a/d ratio) and the ratios of horizontal and vertical crack controlled reinforcement ( ratio). The results indicated that failure mode of deep RC beam changed from diagonal splitting to flexural shear failure when the a/d ratio was increased. Furthermore, the ratio was found to have significant influence on the deformation of the horizontal and vertical reinforcements which could change the failure mode of the beam with the same a/d ratio. Based on the test results, the empirical relationships were introduced to predict the strains in horizontal and vertical reinforcements at maximum applied load. The simplified STM was proposed to separate the effect of reinforcing steels from concrete STM to estimate the shear strength of the test specimens. Finally, the validity of proposed modified STM was verified against the experimental results of 408 samples from various researchers.

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