This is Kuwait National assembly building designed by Jorn Utzon, Danish architect. In your image the building is under construction.
TheyThe 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.