Post-Tensioned Modular Inflated Structures 235 Fig.20.General view and scheme of construction site shelter single hypar module Fig.21.Multihypar structure composed of four modules should be launched in short time,with reduced number of in-site operations. The stowage space required for transportation should be reasonably small. The idea to apply air-inflated elements for structural systems of portable bridges appeared at early stage of development of pneumatic structures,in sixties.Beam-type elements were tested in these early studies [9].However, adoption of such elements caused some problems with wrinkling collapse un- der concentrated load.Another disadvantage of these structures is strictly predetermined span of the bridge,which cannot be changed after manufac- turing.Problems recognized in beam-type bridges can be avoided by means of applying modular,post-tensioned structural systems 10.Post-Tensioned Modular Inflated Structures 235 Fig. 20. General view and scheme of construction site shelter Fig. 21. Multihypar structure composed of four modules should be launched in short time, with reduced number of in-site operations. The stowage space required for transportation should be reasonably small. The idea to apply air-inflated elements for structural systems of portable bridges appeared at early stage of development of pneumatic structures, in sixties. Beam-type elements were tested in these early studies [9]. However, adoption of such elements caused some problems with wrinkling collapse un￾der concentrated load. Another disadvantage of these structures is strictly predetermined span of the bridge, which cannot be changed after manufac￾turing. Problems recognized in beam-type bridges can be avoided by means of applying modular, post-tensioned structural systems [10]