'Clear Span' is an architectural term to describe the distance between the two inside surfaces of the span supports; the distance that is unsupported, if you will.
If you have need in your steel building design for a wide space that is clear of posts and beams, then a clear span design is the choice for you. In essence a clear span design is one that does not have supporting pillars such as those found in pole buildings. A clearspan building offers the most usable space and is ideally suited to factories and warehouses where vehicles such as fork lift trucks are used within the building. Other applications could include sports complexes with full size playing fields and even indoor motocross arenas.
The most common type of single storey building above 10m (30’) span is the steel 'portal framed' building; applications of portal frame buildings include: factories, warehouses, aircraft hangars, schools, gymnasiums & sports centers etc.
For a clear space of less than 70 feet wide, a straight wall column & beam structure can be built. You will still have open space, but are limited to that maximum size.
For a space from 70 to 150 feet in width void of beams or posts, a pre-engineered steel structure is the way to go.
You can choose between a gable style roof (with a peak in the middle) and a roof that slopes one way – a single slope roof. The walls will be straight in both cases. There is no interior support, leaving the entire internal space open. Because of the lack of interior support, the construction of the exterior is heavier than that of a beam and column structure, which does increase the cost. If you have need of a large open space though, that cost difference may not be an issue.
Once your needs go over 150 feet in width, you must use the beam and column construction. Technology for the clear span has not yet reached the point of spanning wider than 150 feet.
For further information on rigid frame designs & building configurations see: steel building styles