Why is minimum reinforcement for flexural members necessary?

The minimum flexural reinforcement is there to prevent brittle failure of the beam. By making sure the reinforced strength of the beam is greater than the moment that causes cracking.

Why is it necessary to impose minimum and maximum limits on the percentage of flexural tension reinforcement What are their values?

Any RCC structure experiences both compressive and tensile loading, it has to be designed as per these forces acting on the structure. On the other hand, a minimum percentage of reinforcement has to be used to provide requisite ductility in the structure which is otherwise missing in pure concrete structure.

What is flexure reinforcement?

Flexural members are slender members that deform primarily by bending moments caused by concentrated couples or transverse forces. In modern construction, these members may be joists, beams, girders, spandrels, lintels, and other specially named elements. But their behavior in every case is essentially the same.

What is flexural failure of a reinforced concrete beam?

Flexural Failures This failure mode occurs when the loads on the beam exceed its flexural capacity. The shear strength of the beam should be greater than its flexural strength otherwise the shear failure would occur before flexural failure.

Why maximum reinforcement is required?

The maximum reinforcement ratio ensures concrete members’ economy and provides safety against brittle failure of concrete. Finally, the required reinforcement area of the designed concrete member should not exceed the maximum reinforcement ratio and should be less than the minimum reinforcement ratio.

What is the purpose of limiting minimum and maximum reinforcement in beam?

The minimum reinforcement ratio controls the cracking of concrete members. The maximum reinforcement ratio is the largest steel area that can be put into concrete members like columns and beam.

What is flexural capacity of beam?

In this concept, the flexural capacity of the concrete beams is the accumulation of two flexural actions, that are due to couple moment of tension and compression forces, and due to the flexural effect of the truss reinforcement system.

Which type of failure is expected in over reinforced flexural members?

compression failure
The primary failure (occurs first) in an over reinforced beam is compression failure, as the crushing of concrete occurs before yielding of the tension reinforcement.

What causes beam failure?

Beam failures could be in flexure, torsion, and shear due to the exceed of the design loads in either failure mode. Depending on the type of load that could exert on the beam and when it reaches the relevant factored load, there is a change of structural failure.

What is the difference between minimum and maximum reinforcement ratio?

The minimum reinforcement ratio controls the cracking of concrete members. The maximum reinforcement ratio is the largest steel area that can be put into concrete members like columns and beam.

What limits the strain in extreme tension reinforcement at nominal strength?

ACI Sec. 10.3.5 limits the strain in the extreme tension reinforcement at the nominal strength. For sections subject to bending

What are the disadvantages of a reinforced concrete beam?

In a reinforced concrete beam, the provision of extra reinforcement above the maximum reinforcement ratio would not be beneficial since the concrete would get crushed before the full strength of steel is used. The collapse of a concrete structure is sudden and does not show any signs before failure.

What is minimum reinforcement in a beam?

Minimum reinforcement is the lowest steel area that prevents early ductile failure of a beam when concrete loses its tensile strength due to imposed loads. Why is minimum shear reinforcement provided in a beam?