WHAT IS PRE-STRESSED STEEL?
The overall reason to pre-stress steel is that it raises both the quality and the resistance to tension and compression characteristics of the steel. Although apparently recent, pre-stressed steel is a material whose origins date back a long way. The adoption of the technique of pre-stressing is attributed to Paxton, who in 1851 utilised this technique for the realisation of the Crystal Palace, unaware of the great discovery he had made. Koenen was the first to propose pre-stressing steel bars . He suggested doing this in 1907, before applying concrete, in order to avoid the formation of cracks and thus stumbled across the innovation of reinforced concrete. Unfortunately his efforts failed because at that time the phenomena of fluage and shrinkage were unknown. In fact, the real “father” of pre-stressing is Eugène Freyssinet, who in 1928 defined it as a technique which consists in subjecting a material, in his case reinforced concrete, to loads which produce stresses opposed to t...