How Columns Are Classified In Reinforced Concrete Design?
How Columns Are Classified In Reinforced Concrete Design?
A reinforced concrete column is a structural part designed to sustain compressive loads that are made of concrete and reinforced with an embedded steel frame. Columns are divided into two types for design purposes: short columns and slender columns.
Short Columns.
The strength of short columns is determined by the material’s strength and the geometry of the cross-section. To improve axial rigidity, reinforcing rebar is put axially in the column. Accounting for steel stiffness, the nominal loading capacity Pn for the column in terms of the maximum compressive stress of the concrete fc’, the yield stress of the steel fy, the gross cross-section area of the column Ag, and the total cross-section area of the steel rebar.
Slender Columns.
Slender columns have a cross-sectional area that is relatively tiny in comparison to their length. Slender Columns, unlike Short Columns, are constrained by geometry and will buckle before the concrete or steel reinforcement fails.
How Do You Reinforce Concrete Columns?
Column strengthening is a method of increasing or restoring the ultimate load capacity of reinforced concrete columns. It is used for seismic retrofitting, sustaining additional live or dead load that was not incorporated in the original design, relieving pressures caused by design or construction mistakes, or restoring original load capacity to damaged structural parts. Reinforced concrete jacketing, steel jacketing, and FRP confining or jacketing are all techniques used to strengthen reinforced concrete columns.
The following are three primary approaches for reinforcing reinforced concrete columns:
- Reinforced Concrete Jacketing. It is one of the strategies used to repair or restore reinforced concrete column capacity. The size of the jacket, as well as the quantity and diameter of the steel bars used in the jacketing process, are determined by the structural study performed on the column. Reinforced Concrete Jacketing Process; 1. Initially, if necessary, temporarily lower or remove loads on columns. This is accomplished by inserting mechanical jacks and other supports between levels.
- If the reinforcements are discovered to be rusted, remove the concrete cover and clean the steel bars with a wire brush or sand compressor.
- Finally, cover the steel bars with a corrosion-resistant epoxy substance.
- If no load reduction or cleaning reinforcement is required, the jacketing procedure begins by inserting steel connections into the existing column.
- The steel connections are installed in the column by drilling holes 3-4mm bigger than the diameter of the steel connectors used and 10-15cm deep.
- The new stirrups of the jacket should be spaced no more than 50cm apart in both vertical and horizontal directions.
- Fill the holes with a suitable epoxy compound before installing the connections.
- Using the same process as in steps 5 and 6, add vertical steel connectors to secure the vertical steel bars of the jacket.
- Installing the new vertical steel bars and stirrups of the jacket in accordance with the dimensions and diameters specified.
- Coating the existing column with an epoxy compound ensures the link between the old and concrete.
- Pour the jacket’s concrete before the epoxy substance dries. Concrete should have a low shrinkage and be made up of tiny aggregates, sand, cement, and other ingredients to avoid shrinkage.
