_______ is provided to support an individual column. It is circular, square or rectangular slab of uniform thickness Sometimes it is stepped or haunched to spread the load over a large area.
Spread footing
Spread Footing Definition
A spread footing is a fundamental type of shallow foundation specifically designed to support a single, individual column or a wall. Its primary function is to safely transmit the concentrated load from the column or wall to a larger area of the underlying soil, thereby reducing the stress on the soil and preventing excessive settlement of the structure.
Characteristics of Spread Footing
The description in the question accurately outlines the key characteristics of a spread footing. Let's analyze each point:
- Individual Column Support: The question states that this footing is provided to support an individual column. This is a defining feature of a spread footing, differentiating it from combined or strap footings that support multiple columns.
- Slab Shape and Thickness: It is described as a concrete slab that can be circular, square, or rectangular in shape. These are the most common geometric forms for spread footings. They typically have a uniform thickness throughout the main body of the slab.
- Load Spreading Mechanism: The goal of any footing is to spread the load over a large area. A spread footing achieves this by having a base area significantly larger than the column cross-section, distributing the load over a greater soil surface.
- Stepped or Haunched Design: The statement mentions that sometimes it is stepped or haunched.
- A stepped footing has changes in its depth, forming steps, to optimize material use while maintaining the necessary load spread.
- A haunched footing features a tapered or sloped profile, often thickening towards the column, which also helps in efficiently transferring the load from the column to the wider base of the footing and can improve structural efficiency.
Footing Types Comparison
To further clarify why spread footing is the correct answer, let's briefly compare it with the other common types of footings listed in the options:
| Footing Type | Description and Primary Application |
|---|---|
| Spread Footing | Supports a single individual column or wall. It is a wide, shallow base, typically a circular, square, or rectangular slab of uniform thickness. It can be stepped or haunched to spread the load over a large area. |
| Combined Footing | Used to support two or more individual columns. This type is often necessary when columns are closely spaced, or when a column is located very close to a property line, preventing the use of a symmetrically loaded spread footing. |
| Strap Footing | Consists of two or more individual footings connected by a concrete beam (strap beam). This is typically used when columns are far apart, or when one column is eccentric (e.g., near a property line) and requires the load to be balanced by an interior footing. |
| Cantilever Footing | Similar in concept to a strap footing, it uses a beam (cantilever beam) to connect an eccentrically loaded exterior column footing to an interior column footing. This is commonly employed when a column is very close to a property line and cannot have its own symmetrically placed spread footing. |
Given the detailed description that it supports an individual column, is a circular, square, or rectangular slab of uniform thickness, and can be stepped or haunched to spread the load over a large area, the footing being described is a spread footing.
Important Questions from Footings
For a number of columns constructed in a row, the type of foundation provided is
If p is the net upward pressure on a square footing of side b for a square column of side a, the maximum bending moment is given by
A. \({\rm{B}}.{\rm{M}} = \frac{{{\rm{pb}}\left( {{\rm{c}} - {\rm{a}}} \right)}}{4}\)
B. \({\rm{B}}.{\rm{M}} = \frac{{{\rm{pb}}{{\left( {{\rm{b}} - {\rm{a}}} \right)}^2}}}{4}\)
C. \({\rm{B}}.{\rm{M}} = \frac{{{\rm{pb}}{{\left( {{\rm{b}} - {\rm{a}}} \right)}^2}}}{8}\)
D. \({\rm{B}}.{\rm{M}} = \frac{{{\rm{pb}}\left( {{\rm{b}} + {\rm{a}}} \right)}}{8}\)
The minimum nominal cover to reinforcement for R.C.C. footings as per IS: 456-2000 shall be
For a proposed building, raft foundation, isolated footings and combined footings are being considered. These foundations are to be listed in the decreasing order of preference in terms of performance. Which one of the following is the correct order of listing?
Which is a method of underwater concreting?
