Q1: As per IS : 456, the reinforcement in a column should not be less than

ANS:D - 0.8% and not more than 8% of cross-sectional area

concrete structures in India. When it comes to the reinforcement in columns, the code specifies the minimum and maximum percentages of reinforcement with respect to the cross-sectional area of the column. The correct range according to IS : 456 is:

• The reinforcement in a column should not be less than 0.8% of the cross-sectional area.
• The reinforcement in a column should not exceed 6% of the cross-sectional area.

Explanation:

1. Minimum percentage of reinforcement (0.8%): This ensures that the column has adequate tensile strength to resist bending and other loads. Insufficient reinforcement could lead to premature failure or inadequate structural performance.
2. Maximum percentage of reinforcement (6%): Excessive reinforcement may result in congestion, making it difficult to properly place and compact the concrete. It can also lead to cracking and reduced durability of the concrete column.

Therefore, the range specified in IS : 456 ensures that the columns have sufficient reinforcement to withstand loads while also preventing issues associated with excessive reinforcement. It's essential for engineers and designers to adhere to these guidelines to ensure the structural integrity and safety of reinforced concrete columns.