The roof structure is concrete slab and there is no other covering surface over the structure of the roof system, other than paint or a clear seal. This attribute does not apply to concrete tiles or fibre cement sheet.


Concrete roof without additional covering, India (S. Brzev)

It is clear that the roof structure is made from concrete, but the type of concrete system is unknown. The system may be hidden, or information about it is unavailable.

Concrete that is reinforced by metal, usually steel rods or bars cast into the concrete, or by other reinforcement such as glass or metal fibres or natural materials that are strong in tension.

Includes prestressed concrete, and can be pre-cast or cast-in-place.


Reinforced concrete slab and columns under construction, Canada (S. Brzev)

reinforced concrete - 1


Reinforced concrete building, New Zealand (A. Charleson)


Reinforced concrete wall and column retrofitted with carbon fibrewrap, USA (S. Brzev)

Members of the lateral load-resisting system consist of large metal or steel sections filled with or encased in concrete to increase their strength rather than for fire-protection only.

Sometimes this composite structural material or steel reinforced concrete (SRC) is used in conjunction with other materials like reinforced concrete or steel construction. For example, a SRC frame might be constructed above or below some reinforced concrete frame stories, or a building might contain both SRC and reinforced concrete or steel frames. In these situations one has to assess whether the SRC frames or members will define the seismic performance of the overall structure. If that is not the case then the other structural material should be selected.

The structural material is concrete, but it is not known if the concrete is reinforced or unreinforced.