Question

10.3 What are the minimum and maximum percentages of steel allowed in an reinforced concrete column? Explain why it is necessary to specify these percentages.

Answer 1

Solution:-

Maximum and minimum percentage of steel allowed in column:-

minimum area of steel allowed in column is 0.8% of the gross area of column, maximum area of steel allowed in column when bar are not lapped is 6% of the gross area of column and maximum area of steel when bar are lapped is 4% of the gross area of column.

minimum area of steel(Asmin)=0.8% of the gross area of column

maximum area of steel when bar are not lapped(Asmax)=6% of the gross area of column

maximum area of steel when bar are lapped(Asmax)=4% of the gross area of column

the use of 6% or more area of reinforcement may involve paractical difficulties in placing and compacting of concrete, hence lower percentage is recomended. but not less than minimum area of steel allowed in column becasue the percentage of reinforcement is less than 0.8% the column ductility is negligible or very and column bending strength is also negligible. so we provide the area of stee in between 0.8% to 6% of the gross area of column.

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