Title:
GCRTA Special Bridge Inspection: Instrumentation, 3D FEM Calibration, and Analysis of an In-Service LRT Bridge
Author(s):
Kent Dickens, Nick Amico
Publication:
Web Session
Volume:
Issue:
Appears on pages(s):
Keywords:
DOI:
Date:
10/25/2020
Abstract:
In Fall 2016, a 1,010 ft tendon running continuously through five spans of the main span unit on the I-526 Wando River Bridge was found ruptured. Evaluation of the tendon determined that it failed due to the presence of grout voids and infiltration of water leading to corrosion. The failure of this tendon, one of eight external tendons in the westbound main spans, raised interest in the condition of the remaining 599 external tendons of both bridges. SCDOT commissioned a team of engineers and specialists led by HDR to conduct an evaluation of the post-tensioning system and design and implement repairs. The assessment program utilized magnetic flux scanning of external tendons to locate areas of strand section loss, capacitive probe testing to identify voids in the grout, and borescope inspections to visually assess the condition of tendon anchors and high points. Grout samples were tested in the laboratory for chlorides, sulfate, and moisture content, as well as petrographic analysis. Three-dimensional staged construction models and comprehensive finite element solids models were developed to facilitate the design of tendon replacements, segment joint repairs, and a supplemental post-tensioning system capable of compensating for the loss of tendons that could not be removed and replaced.