The number of post-tensioned roof girders, used on a large scale in Poland between 1954-1974, is estimated to be tens of thousands. Nowadays, these elements are still utilized, sometimes in different conditions than those provided in the original project. Despite restricted recommendations for diagnosing, many technical assessments can be found, which do not take into account the specific characteristics that distinguish post-tensioned girders from typical reinforced concrete structural elements. This often leads to incorrect conclusions and results in recommendations of unnecessary or even harmful repair works; or even worse, ignoring the symptoms of real danger of failure. This article presents briefly selected issues and principles of diagnostics of post-tensioned concrete elements providing examples of common faults.

Keywords: post-tensioned girder, technical assessment, diagnostics.