Abstract: An air beam structure having reduced weight, increased rigidity, and lower inflation pressure requirements. The structure includes a closed tubular cylindrical shell of air impermeable fabric having at least one inflation valve. Fixed within the shell is an “I” beam envelope comprised of flexible, air impermeable walls sealed to the interior of the shell. The “I” beam envelope extends the length of the shell and defines at least four air chambers in communication with the inflation valve. A quantity of compressible material is dispersed throughout the interior of the “I” beam envelope. When subjected to compressive forces by pressurization of the air chambers, the material becomes rigid. The filled envelope is either vented to atmosphere or connected to a vacuum source. The air beam is used in groups and may be connected one to another by sheet materials to form a wall or roof structure.