FRICTION LOSS AND ELONGATION OF PRESTRESSING STEEL IN POST-TENSIONED FLAT SLAB

Abstract

This study was to evaluate the friction loss and elongation of prestressing tendon in post-tensioned flat slab. The typical layout of the carpark building was selected in this study. A comparison between the calculated elongation and the measured value was conducted for the tendon. The designed elongation was calculated from the tendon profiles indicated in the construction drawing. The site deviation which was the deviation of the tendon profiles measured in the installation process were collected to calculate of the deviation of friction loss and elongation. The calculated elongations were compared with the collected data measured from the ram after stressing. It was revealed that the calculated elongation and the measured elongation was deviated up to 11.10%, which was greater than the allowable limit of 7.00%. This deviation was due to the discrepancy between the design tendon profile and the actual construction, which contributed up to 40% of the total deviation. The effect of site deviation played an important role on the elongation which should be taken into account in the design.