Does anyone know what these things on the ceiling of this building are called?
I am referring to those objects with semicircle shape that act as a ceiling on the top of the building.
Engineering Stack Exchange is a question and answer site for professionals and students of engineering. It only takes a minute to sign up.Sign up to join this community
This is Kuwait National assembly building designed by Jorn Utzon, Danish architect. In your image the building is under construction.
The objects are permanent formwork for roof concrete slab. They create the grooves on top that is going to be populated with reinforcement and mold the stem of T-beam Roof slab.
At the same time, they are nicely arched on the bottom and will play as the dramatic voluted ceiling of the building.
He utilizes this type of architectural feature in many of his designs.