RELAXATION BEHAVIOR OF PRESTRESSING STRANDS

THIS REPORT DESCRIBES THE DEVELOPMENT AND APPLICATION OF FUNCTIONAL EXPRESSIONS FOR THE PREDICTION OF PRESTRESS LOSS IN PRESTRESSING STRANDS. PARTICULAR ATTENTION IS PAID TO THE SELECTION OF SUITABLE TIME-DEPENDING FUNCTIONS ALLOWING AN EXTRAPOLATION OF THE LONG TERM RELAXATION LOSS. IN ADDITION, A GENERAL STRESS-STRAIN-TIME RELATIONSHIP OF PRESTRESSING STRANDS IS DERIVED WHICH ALLOWS THE ESTIMATION OF THE REMAINING STRESS FOR GIVEN VALUES OF STRAIN AND TIME. A COMPARISON WITH ALTERNATIVE METHODS IS MADE AND QUANTITATIVE ESTIMATES OF THE MAGNITUDE OF ERROR ARE GIVEN. THE APPLICATION OF THE STRESS-STRAIN-TIME RELATIONSHIP TO SEVERAL PROBLEMS RELATED TO THE PREDICTION OF PRESTRESS LOSS IS ILLUSTRATED IN A NUMBER OF EXAMPLES. /AUTHOR/