Various types of Reinforcement in footings or types of mesh found in foundation

In footings, there exist various types of Reinforcement. The reinforcement in Footings should be added for tension requirements. Normally, the percentage of reinforcement in footings remains among 0.5% to 0.8%.

Based on the load analysis, the structural engineer design the type of Mesh to be utilized in footings. Given below, the details of various types of mesh (reinforcement) utilized in several types of footings or foundations.

Normally, four types of reinforcement are found in footings or foundations:–

1. Plain Mesh: This type of Mesh is generally found in Plain or Isolated or combined footings. It is suitable for low-rise buildings. Prior to provide plain mesh, one should analyze the load in relation to this mesh and take decision whether the type of mesh is compatible with the load or not.

Under this type, the bars are arranged as a grid. It may contain bars with various diameter and spacing in either direction. There may be or may not be the variation with the spacing in both directions.

2. Mesh with hooks (Hook Mesh): This type of mesh is ideal for low rise and high rise buildings. The footing is reinforced as grid and at the ends of the mesh, the bars are attached with hooks. If the ends of the bars are bent, the exact anchorage of the reinforcement is obtained. If the hook length is given as 9D, here D denotes the diameter of the bar.

3. Footing Mesh up to the depth of Footing: It has similarity with the Plain footing. In this type, the bars are bent at ends up to a height of footing. The concrete cover of 1″to 4″is arranged in all the sides of footing.

4. Raft Mesh: This type of Mesh is found in Raft footing. Raft footing is effective when soil bearing strength is very low. In this type, Mesh is segregated into two parts, Top mesh and Bottom Mesh.

Initially, the bottom mesh is set on covering blocks, ends of a bottom mesh are bent at an angle of 90 degree up to a height of 50D where D means Diameter of Bar. After that the top mesh is affixed with the bottom mesh in reverse direction. Besides, the top mesh is equivalent to bottom mesh bent with 90 degrees but a supplementary bar of 50D is not arranged since it is already provided with bottom mesh.

The 50D supplementary bar is arranged either on bottom or top mesh.

Single ring along with double ring are joined with top mesh and bottom mesh to retain the perfect framework. The rings facilitates the Steel reinforcement to get rid of distortion in any direction. Minimum Diameter of Bars for rings should be 6 mm.

In single ring, Raft mesh rings are provided in only one direction either horizontal or vertical; but in Double ring System, the rings are arranged in both the direction.

Article Source: civilread.com