ANALYSIS AND EVALUATION OF DAMAGE TO PRESTRESSING STEELS ON THE BASIS OF AVAILABLE KNOWLEDGE

ANALYSE UND AUSWERTUNG VON SCHADENSFAELLEN AN SPANNSTAEHLEN UNTER BERUECKSICHTIGUNG VORLIEGENDER ERKENNTNISSE

PRESTRESSING STEELS IN LARGE STRUCTURES HAVE RECENTLY SUFFERED DAMAGE, THE CAUSE OF WHICH IS UNKNOWN; THE STEELS IN QUESTION ARE PERMITTED PRESTRESSING STEELS WHOSE SUSCEPTIBILITY TO FAILURE COULD NOT BE PREDICTED ON THE BASIS OF KNOWN MATERIAL PROPERTIES. AN ANALYSIS IS TO BE MADE OF DAMAGE WHICH HAS OCCURRED. EXISTING REPORTS ON DAMAGE ARE TO BE EVALUATED AND FURTHER (APPROXIMATELY 20) COMPREHENSIVE STUDIES UNDERTAKEN ON EXISTING CASES OF FAILURE DAMAGE. IT HAS BEEN NECESSARY TO EXTEND INVESTIGATIONS INTO: (A) THE SITE CONDITIONS; (B) THE MATERIAL - PARTICULAR ATTENTION BEING GIVEN TO CRACKS AND THE MICRO STRESSES PRESENT IN CRACKS; (C) THE CHARACTER OF THE FAILURE (REM) TESTS; (D) THE PRESENCE OF CORROSION PRODUCING AGENTS AT THE FAILURE POINT; (E) COMPARATIVE MECHANICAL-TECHNOLOGICAL STUDIES (IMPACT TESTS) ON THE MATERIAL. AN ATTEMPT IS BEING MADE TO DISCOVER WHETHER THE CURRENT RECOMMENDATIONS FOR THE AVOIDANCE OF FAILURE OF HIGH STRENGTH STEELS CAN BE RECONCILED WITH THE FINDINGS OF CASE STUDIES INVOLVING DAMAGE.