Bonding of External Tendons at Deviators.

摘要

The report is the first in a series outlining a major study of techniques for improving the ductility and strength of post-tensioned concrete box girder bridges through improved bonding of external tendons. It presents a detailed state-of-the-art report concerning bonding of tendons through cement grouting. More importantly, it presents the results of a series of realistic pullout tests for tendons grouted in curved deviator pipes typical of modern segmental technology. Six specimens were tested with varying deviation angles and ratio of prestressing tendon area to duct cross-sectional areas. Detailed measurements and observation of overall behavior led to a very good understanding of the bond-slip relationship for the tendons in the local region of the curved deviator. In addition to the full-scale direct tension bond stress-slip tests of full-scale deviator specimens, two additional test series are reported. The first is a series of residual tension load tests in which the state of stress of tendons discretely bonded at multiple points was investigated by selective cutting between bonding points and measuring the residual load patterns. The second is a series of eighteen tests evaluating different materials and procedures for remedial bonding of tendons at pass through locations.