Reinforcement Cement Concrete (General Engineering) (SSC JE)

• The role of lateral ties is to prevent premature buckling of bars, improve strength, to provide resistance against shear and torsion, to hold bars in position during construction etc.

The cantilever beam carry gravity load, top fibers above neutral axis are subjected to tensile stresses so main reinforcement is provided above the neutral axis.

High strength concrete is necessary for the following reasons–
• When the stress is transferred to concrete by bond action, the high strength concrete offers high bond stress.
• Shrinkage cracks will be very little.
• Due to the larger modulus of elasticity of high strength concrete, the elastic and creep-strain are small resulting in smaller loss of pre-stress in the steel reinforcements.

Prestressed cement concrete–If tensile stresses in concrete are neutralized by introducing initial compressive stresses, such concrete is known as prestressed cement concrete.

In pre-stressed concrete high strength concrete and steel are desirable because–
• The smaller cross-section of member results in smaller self weight.
• High bearing stresses are generated in anchorage zones
• The shrinkage cracks are reduced, with higher modulus of elasticity and smaller creep strain.