Fundamental Assumptions for the Design of Reinforced Concrete

Fundamental Assumptions for the Design of Reinforced Concrete

One can calculate the performance of reinforced concrete members using the essential assumptions for reinforced concrete design. Of course, the design and analysis of concrete structures are based on the structural mechanics as well as comprehensive testing.

The structural mechanics, one of the primary methods used for the analysis and design of reinforced concrete elements, is built on the fundamental assumptions of reinforced concrete design.

Determine the general shape and the precise dimensions of a structure so that it can perform the function for which it is intended and safely withstand external influences during its useful life. This is the main responsibility of a structural engineer.

Fundamental Assumptions for Reinforced Concrete Behavior –

The fundamental propositions on which the mechanics of reinforced concrete is based are as follows:

  • Any part of a member has internal forces, such as bending moments, shear forces, and normal and shear stresses, which are in balance with the effects of the external loads there.
  • Sections that are flat before bending and are perpendicular to the axis of bending stay so after bending.
  • It is expected that there is perfect bonding between the steel and concrete at the contact, preventing any slippage between the two components.  Hence, as the one deforms, so must the other. This assumption is very near to being accurate because current deformed bars give a significant degree of mechanical interlocking in addition to the inherent surface stickiness.
  • The concrete in the part of a member that is in tension is typically broken because the tensile strength of concrete is only a small portion of its compressive strength. While these cracks, in well-designed members, are generally so narrow as to be hardly visible (they are known as hairline cracks), they evidently render the cracked concrete incapable of resisting tension stress. As a result, it is considered that concrete is unable to withstand any kind of tension stress.

The actual stress-strain relationships and strength characteristics of the two constituent materials serve as the foundation for the theory.