A beam that is prestressed at the lower portion experiences what internal forces at the top and bottom?

When a beam is prestressed at the lower portion, it is intentionally subjected to compressive forces that counteract the tensile stresses that occur when the beam is loaded. This means that, as the beam is loaded, the tension that develops at the bottom due to the applied loads is countered by the prestressed compressive forces.

As a result, the bottom portion of the beam, where the prestressing occurs, experiences compression due to the established internal force from the prestressing tendons. Conversely, the top side experiences tension as it is the side that tends to elongate or stretch when the beam is loaded. Thus, when considering the internal forces in the prestressed beam, the top portion will be in tension while the bottom portion remains in compression. This interaction is essential for the performance of prestressed concrete beams, as it enhances their capacity to carry loads effectively and maintains structural integrity under various conditions.