Elevated temperature creep model of parallel wire strands

Parallel wire strands (PWSs), which are widely used in prestressed steel structures, are typically in high-stress states. Under fire conditions, significant creep effects occur, reducing the prestress and influencing the mechanical behavior of PWSs. As there is no existing approach to analyze their creep behavior, this study experimentally investigated the elevated temperature creep model of PWSs. A charge-coupled camera system was incorporated to accurately obtain the deformation of the specimen during the elevated temperature creep test. It was concluded that the temperature level had a more significant effect on the creep strain than the stress level, and 450 & DEG;C was the key segment point where the creep rate varied significantly. By comparing the elevated temperature creep test results for PWSs and steel strands, it was found that the creep strain of PWSs was lower than that of steel strands at the same temperature and stress levels. The parameters in the general empirical formula, the Bailey-Norton model, and the composite time-hardening model were fitted based on the experimental results. By evaluating the accuracy and form of the models, the composite time-hardening model, which can simultaneously consider temperature, stress, and time, is recommended for use in the fire-resistance design of pre-tensioned structures with PWSs.

Automated summary

This study experimentally investigated the elevated temperature creep behavior of parallel wire strands (PWSs) and concluded that temperature level had a more significant effect on creep strain than stress level, with 450°C being the key segment point. The creep strain of PWSs was lower than that of steel strands at the same temperature and stress levels. The composite time-hardening model, which considers temperature, stress, and time simultaneously, is recommended for fire-resistance design of pre-tensioned structures with PWSs.