What is known as the spread footing for a single column?
🔬 Understanding Spread Footings
A "spread footing" is a general term for any type of shallow foundation that "spreads" the concentrated load from a column or wall over a larger area of soil. This reduces the pressure on the soil to a level it can safely support. The question asks for the specific name of a spread footing that supports just one column.
⚖️ Detailed Analysis of the Options
Let's evaluate each term to find the most accurate and specific name.
(d) Pad footing
Why it's correct: This is the most common and technically correct term for a spread footing that supports a single, individual column. It is also known as an isolated footing. It is typically a square or rectangular pad of reinforced concrete designed to distribute the column load.
(a) Stepped footing
Why it's incorrect: A stepped footing is a type of footing that changes levels in a series of steps. It is used on sloping ground to keep the foundation horizontal or to provide a deeper foundation for a specific part of a structure. It describes the shape in elevation, not its function of supporting a single column.
(b) Single footing
Why it's not the best answer: While descriptive, "single footing" is not the standard technical term used in engineering. The correct and more professional terms are "pad footing" or "isolated footing."
(c) Sloped footing
Why it's incorrect: A sloped footing, also known as a trapezoidal footing, is a type of pad footing where the top surface is sloped downwards from the column to the edges. This shape helps to save concrete while maintaining the required thickness at the critical section for shear. It describes a specific shape of a pad footing, not the footing type itself.