The correct answer is: D. Composite beams
A composite beam is a beam composed of more than one material, rigidly connected together so as to behave as one piece. The most common type of composite beam is a steel-concrete beam, in which a steel beam is encased in concrete. The steel provides strength and stiffness, while the concrete provides fire resistance and durability.
Other types of composite beams include wood-concrete beams, aluminum-concrete beams, and glass-concrete beams.
Composite beams offer a number of advantages over traditional solid beams. They are stronger and stiffer, which can allow for longer spans and larger loads. They are also more resistant to fire and corrosion. Additionally, they can be more cost-effective, as the materials can be used more efficiently.
However, composite beams also have some disadvantages. They can be more difficult to design and construct, and they may require special connectors. Additionally, they may be more susceptible to cracking and delamination.
Overall, composite beams offer a number of advantages over traditional solid beams. They are stronger, stiffer, and more resistant to fire and corrosion. Additionally, they can be more cost-effective. However, they can also be more difficult to design and construct, and they may require special connectors.