<p>A pneumatic structure (10) in the form of a barrel roof which has openings at the opposite ends thereof includes outer and inner walls (12,14) of a sheet or membrane material connected by a plurality of partition walls (16) in the form of ribs provided therebetween to define a plurality of air compartments in the form of ribs between the outer and inner walls. The partition walls (16) includes a plurality of openings (18) for fluid communication between adjacent air compartments. The pneumatic structure (10) has specific dimensions defined as follows. <MATH> <MATH> <MATH> <MATH> where a : the maximum opening width of the pneumatic structure (10); b : the total width of the pneumatic structure (10); c : the effective height (between ground and the maximum height of the inner wall (14); and d : the total height (between ground and the maximum height of the outer wall (12). <IMAGE></p>
