Force monitoring in steel-strand anchor cables using quasi-distributed embedded FBG sensors

Abstract

A theoretical analysis and experimental verification of the stress distribution in prestressed steel-strand anchor cables over their entire length were conducted in this study combining quasi-distributed embedded FBG sensing, prestress loss principles and fundamental deformation theory. Four series of steel-strand anchor cable pull-out tests were conducted with variable free section lengths, anchorage lengths and strain monitoring point locations. A difference not exceeding 2 % between the stress in the anchor cable free section measured by the quasi-distributed FBG sensors and the theoretical values calculated considering concrete prestress loss was observed. A relationship between the effective anchorage length and the effective prestressing force was deduced from the stresses recorded by the FBG sensors in the cable anchorage section. Combined with the fundamental theory of deformations, the stresses in the anchorage section were then calculated and compared with the experimental values. The errors generally did not exceed 10 %.