What type of concrete slab is directly supported by columns without beams or joists?

Flat slabs are a type of concrete slab that is directly supported by columns without the need for beams or joists. This design allows for a much simpler and more efficient construction process, as it eliminates the additional structural elements, resulting in faster construction times and reduced labor costs.

The flat slab design is particularly beneficial in buildings where a clean, column-free space is desired, such as in parking garages or large commercial buildings. The absence of beams allows for greater flexibility in spatial configuration and can improve aesthetic considerations by minimizing the visual obstructions caused by traditional beam systems.

In addition to their structural advantages, flat slabs can also be more easily integrated with other building systems, such as HVAC and lighting, as the entire ceiling can be used without interference from beams. Furthermore, they tend to allow for increased floor-to-floor heights, making them advantageous in many architectural applications.