What is Footing?
In this article, we are going to discuss Strap Footing – Its Types, Advantages & Disadvantages.
Basically, Footing is a component of the foundation of any building that is base and helps distribute the weight of the entire building equally and ensures stability. The purpose of footing is to transfer a load of building to the soil it is constructed on. Relying upon the aim, purpose, quality, and weight-bearing capability of the footing they are divided into several types. Different types are used for construction purposes they are suitable.
- Slope footing
- Isolated Footing
- Strap Footing
- Strip Footing
- Stepped Footing
- Compound Footing
- Raft Footing
- Pile Footing
- Continuous Wall Footing
Compound footing has more than one column. It is used only when you are left with no other option. Mostly it is used when the soil has less load-bearing capability than required. In compound footing distance of the column from the edge is sufficient
Compound footing is further divided into 3 types.
- Tee- Shaped
When columns are close to one another compound footing is given preference but when the situation is opposite and has a large distance between columns strap footing is considered.
Strap footing is a unique kind of compound footing with some additional parameters. In the case of strap footing distance of the column from the edge is very small that it might need extra excavation. So, this footing is prioritized when we have limited space for foundation so, instead of separate footings, they are associated with a solid concrete bar. This connecting bar or beam is called strap beam or strap footing. It is utilized to help disperse the heaviness of either intensely or whimsically stacked segment footings to nearby footings. The objective is to have a uniform bearing pressing factor and to limit differential settlement between sections.
A strap footing is built between the outside balance and the nearby inside balance the reason for the strap is to limit the toppling power because of the eccentric burden on the outside balance.
The base regions of the footings are proportioned so the bearing pressing factors are uniform and equivalent under the two bases. In this manner, it is fundamental that the resultant of the heaps on the two footings should go through the centroid of the territories of the two bases. The strap beam between the footings should not bear against the soil, henceforward the ground straightforwardly beneath the beam needs to be free and left uncompacted.
Before strap footing, many aspects are required to be studied and are listed below.
- Soil pressure under strap footing
- Shear Calculation
- Longitudinal Stresses
- Distribution of Forces
Advantages of Strap Footing
- It helps distribute load uniformly and transfer moment to the adjacent footing.
- It prevents the column from tilting.
- The employment of a strap footing may be excusable where the gap between columns is long and a regular combined footing is impractical due to the required massive excavation.
Disadvantages of Strap Footing
- Strap footing requires more concentration while it has been constructed because it has a difficult design.
- It can become more time-consuming comparatively as the calculation of pressure bearing, pressure distribution, moment, forces, and shears can become complex.
- It will demand expert workers for its construction.
In short, we should avoid using strap footing until conditions force us to do so. Under normal circumstances, we can go for other types of footings. When using strap footing in construction we should perform calculations keenly. Any miscalculation can lead to a massive loss like a tilting of the building.
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