Abstract
Reinforced concrete (RC) beams are generally designed with different percentages of flexural tension reinforcement depending on the capacity requirements. The amount of reinforcement provided affects the crack propagation and failure mechanism in RC beams. This paper presents discussion on the minimum tension reinforcement requirement in code provisions for RC beams. Models based on fracture mechanics to evaluate minimum flexural reinforcement are also reviewed. Experimental study has been undertaken to understand the effect of size on the behaviour of lightly RC beams. This paper outlines how the present code provisions can be improved by applying fracture mechanics principles for the design of RC beams. Fracture mechanics approach for design of RC structures considers the energy requirements for crack growth and size effect. It also enables rational procedure to evaluate the optimum amount of steel reinforcement, which ensures safe designs by taking the effect of size and other influencing parameters.
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Abbreviations
- As,min (ρmin):
-
Minimum area of steel
- A s :
-
Area of steel
- b :
-
Breadth of beam
- d or h:
-
Effective depth of beam
- d′:
-
Clear cover
- D :
-
Overall depth of beam
- E c :
-
Modulus of elasticity of concrete
- E s :
-
Modulus of elasticity of steel
- f ck :
-
Characteristic cube compressive strength of concrete
- f′ c :
-
Cylinder compressive strength of concrete
- f t :
-
Tensile strength of concrete
- f r :
-
Modulus of rupture
- f y :
-
Yield strength of steel
- K Ic :
-
Critical stress intensity factor in mode I
- M CR :
-
Moment of crack propagation
- M y :
-
Moment at steel yielding
- Np:
-
Brittleness number
- FPZ:
-
Fracture process zone
- FCM:
-
Fictitious crack model
- LEFM:
-
Linear elastic fracture mechanics
- NLFM:
-
Non-linear fracture mechanics
References
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Nagesh, H.E., Appa Rao, G. (2019). Evaluation of Minimum Flexural Reinforcement in Design of Reinforced Concrete Beams. In: Rao, A., Ramanjaneyulu, K. (eds) Recent Advances in Structural Engineering, Volume 1. Lecture Notes in Civil Engineering , vol 11. Springer, Singapore. https://doi.org/10.1007/978-981-13-0362-3_12
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DOI: https://doi.org/10.1007/978-981-13-0362-3_12
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