ANS:D - strip

In a reinforced concrete (RC) framed structure with multiple columns, the type of foundation provided depends on various factors such as the soil conditions, structural loads, and architectural constraints. Typically, different types of foundations may be used for different columns within the structure. Here's a breakdown of the possible foundation types:

1. Footing: Footings are typically used for individual columns or small groups of columns. They distribute the load from the columns to the underlying soil, ensuring that the soil pressure remains within acceptable limits. Footings come in various shapes and sizes, such as square, rectangular, or circular, depending on the column loads and soil bearing capacity.
2. Raft: Raft foundations, also known as mat foundations, are used when the soil bearing capacity is relatively low or when the columns are closely spaced. A raft foundation extends beneath the entire footprint of the structure, distributing the loads from multiple columns over a larger area of soil. This helps reduce the pressure exerted on the soil and prevents differential settlement.
3. Strap: Strap footings are used to connect individual footings or raft segments together, forming a continuous foundation system. They are commonly employed in structures with eccentrically loaded columns or in situations where differential settlement needs to be minimized. Straps transfer loads from one footing or raft segment to another, ensuring uniform distribution of loads and enhancing the overall stability of the foundation system.
4. Strip: Strip footings, also known as continuous footings, are long, narrow footings that support a row of columns or a load-bearing wall. They are used when columns are closely spaced along a line or when the loads from adjacent columns can be combined into a single footing. Strip footings are economical and efficient for distributing loads over a relatively large area of soil.
5. Combination: In some cases, a combination of different foundation types may be used within the same structure. For example, a structure may have a combination of individual footings, raft segments, and strap footings, depending on the specific requirements of each column and the soil conditions at different locations within the building footprint.

In summary, the type of foundation provided for a reinforced concrete framed structure with multiple columns may involve the use of footings, rafts, straps, strips, or a combination thereof, depending on factors such as soil conditions, structural loads, and design considerations. Each type of foundation serves a specific purpose in distributing loads and ensuring the stability and integrity of the structure.