[A + (m - 1)A_SC] known as equivalent concrete area of R.C.C. is given by

ANS:A - modular ratio method

The expression A+(m−1)ASC represents the equivalent concrete area of reinforced concrete (R.C.C.). This concept is utilized in the modular ratio method, which is a widely used approach in reinforced concrete design. In the modular ratio method, the equivalent concrete area is determined to simplify the analysis of reinforced concrete sections. The formula you provided is a part of this method, where:

• A represents the actual area of concrete,
• S represents the area of steel reinforcement, and
• m is the modular ratio, which is the ratio of the modulus of elasticity of steel to that of concrete.

The expression A+(m−1)ASC is used to calculate the transformed or equivalent concrete area that accounts for the contribution of steel reinforcement to the overall strength and stiffness of the reinforced concrete section. Therefore, the correct answer is: modular ratio method