Tensiones internas de compresión y relajación, en aceros de pretensado

Internal stress and creep in prestressed wires

To study the deveolpment and amount of wire shorenings some measurements had been made during different time intervals and temperatures between 150 and 240 º C. Creep tests had also been made with samples submitted to heat treatment as well as untreated samples. It had been observer that the shortening suffered after the heat treatment omcreases as bigger the creep is. In order to simulate in the Laboratory the L.R. process, we have used a procedure which generates a "compressive stress" on the wires similar to those obtained in theh industrial process. The load and temperature parameters determine the values of the "compressive stresses" and their development through time as a result of the heat treatment. Finally, some conclusions have been drawn and, moreover, it sems possible that a close investigation may lead to a new procedure of testing the creep or the relaxation.