Which of the following is a characteristic of a pile cap?

• A. It is always made of wood
• B. It is a thin layer of concrete
• C. It connects multiple columns directly
• D. It acts as a unit in supporting structural loads

Answer: (D)

A pile cap is a robust structural element that is placed on top of a group of piles. Its primary function is to distribute loads from the superstructure above into the piles below. By acting as a unit, the pile cap helps ensure that the loads are evenly distributed across the pile foundations, which contributes to the stability and integrity of the overall structure. This characteristic is crucial in situations where soil conditions may be inadequate to support the loads directly or where settlement could be a concern.

Choosing this characteristic underscores the pivotal role of a pile cap in foundation design, especially in heavy load situations or in soft soil conditions. The other options do not accurately describe a pile cap's fundamental attributes—such as being made of wood, being a thin concrete layer, or merely connecting columns. Instead, the emphasis on acting as a unit in load support highlights its importance in foundation engineering.