Correct Answer - Option 1 : slender
Explanation:
- A column of rectangular section is considered slender if any of the two slenderness ratios is equal to or more than 12.
- if both the slenderness ratios is less than 12 then it is called a short column.
Braced Columns
-
When a structure subjected to lateral forces such as wind load and earthquake load, these loads are resisted by using bracing, called braced column in framed structure. So, the braced column is not designed to resist these forces. The main advantage of the braced column is that lateral sway is zero.
Un-braced Column
- Un-braced columns are basically those columns that are designed to resist the lateral loads caused by wind load and earthquake loads. It is used for areas that are less prone to earthquakes.
As per IS 456: 2000, clause 26.5.3.1,
Longitudinal reinforcement in a column:
Percentage of steel:
The cross-sectional area of longitudinal reinforcement shall be
- not less than 0.8 percent of the gross cross-sectional area of the column
-
nor more than 6 percent for unlapped bars of the gross cross-sectional area of the column
- nor more than 4 percent for lapped bars of the gross cross-sectional area of the column
The minimum number of longitudinal bar:
The minimum number of the longitudinal bar provided in column shall be
- four in rectangular columns
- six in circular columns
Percentage of steel:
The cross-sectional area of longitudinal reinforcement shall be not less than 0.8 per cent nor more than 6 per cent of the gross cross-sectional area of the column.
The minimum diameter of longitudinal reinforcement bars:
The main longitudinal reinforcement bars used in the column shall not be less than 12 mm in diameter.
Spacing:
The spacing of longitudinal bars measured along the periphery of the column shall not exceed 300 mm.
