Relaxation Tests on Alloy Steel Bars

The object of this research was to determine the relaxation of stress for alloy steel bar prestressing tendons made in Australia. For convenience, the research work was broken up into three basic sections: (1) Determination of significant controllable and uncontrollable variables through literature survey; (2) development of adequate methods of measuring relaxation for different sets of variables (the apparatus developed was based on the load balancing principle); and (3) generalization of relaxation results through statistical design and analysis of experiments. A performance model was developed to allow predictions to be made; while in addition, quantitative relaxation values are recommended for adoption in current design.