Final answer:
The top and bottom of beams are reinforced to handle compression and tension forces. The use of I-beams in modern construction helps to distribute these forces more effectively.
Step-by-step explanation:
The top and bottom of beams are reinforced to better handle the forces of compression and tension. For example, in modern building construction, I-beams are commonly used to reduce bending strains. These I-beams have a shape that distributes the forces of compression and tension more effectively, allowing them to bear heavier loads without bending or sagging. The shape of the I-beam is designed to have a larger cross-sectional area at the top and bottom, which helps to handle the forces of compression and tension.