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Title |
Practical Design Method of Reinforced Concrete Deep Beams (II) Improved Design Method
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DOI |
https://doi.org/10.4334/JKCI.2022.34.5.523 |
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Keywords |
스트럿-타이 모델; 깊은보; B-영역; D-영역; 전단 설계 strut-tie model; deep beams; B-region; D-region; shear design |
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Abstract |
The Strut-Tie Model in the KDS 14 20 24 code can efficiently calculate the strength of RC deep beams by using the force equilibrium condition, but the calculation process is too complex to be applied to the RC deep beam design. In addition, it causes discontinuities in the amount of vertical shear reinforcement at the boundary of the B-region and D-region, and the amount of reinforcement required depends on the selected model. In this study, a strut-tie method with a direct strut was proposed to calculate the shear reinforcement taking into account the influence of the shear span-to-depth ratio. The proposed model showed that as the span- to-depth ratio decreased the effective strength of the concrete strut increased, but the required amount of vertical shear reinforcement decreased. A method of calculating the effective compressive strength of the direct strut is proposed to eliminate the discontinuity in the amount of vertical shear reinforcement at the boundary (=2.0) of the B-region and D-region. Practical STM can increase the reliability of STM for structural engineers by eliminating discontinuities at the boundary of the B- and D-regions and differences in calculation results depending on the selected model.
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