What type of beam has a top rail that is joined by a series of smaller pieces called truss blocks?

A trussed beam is specifically designed to incorporate a series of smaller components, known as truss blocks, that connect its top rail. This configuration enhances the structural integrity and load distribution of the beam. The truss blocks work in tandem to form a triangular framework, which is known for its strength and stability.

This type of beam is particularly advantageous in construction and engineering settings where long spans are required without excessive weight, making it effective for large structures such as roofs and bridges. The inclusion of truss blocks not only reduces the amount of material needed but also allows for efficient use of space.

In contrast to solid beams and I-beams, trussed beams are designed specifically with these connecting elements for improved performance under load. A solid beam comprises a singular piece of material with a consistent cross-section, lacking the intricate design that allows for distributed loads through truss blocks. An I-beam also does not utilize truss blocks; rather, it has an I-shaped cross-section providing strength in specific directions but not the triangular support system provided by truss blocks in a trussed beam. Thus, the distinctive feature of truss blocks clearly identifies the trussed beam as the correct answer.