Title:
Time- and Temperature-Dependent Deflection Monitoring of the I-35W St. Anthony Falls Bridge
Author(s):
Hedegaard
Publication:
Web Session
Volume:
ws_S23_HedegaardTime.pdf
Issue:
Appears on pages(s):
Keywords:
DOI:
Date:
4/2/2023
Abstract:
Instrumentation for full-scale structures provides valuable insight in understanding concrete creep and shrinkage behavior in field conditions over many years. The monitoring system of the I-35W St. Anthony Falls Bridge offers a unique opportunity to evaluate a structure from ‘birth’. Long-term displacement has been measured using linear potentiometers at the bearings, with thermistors distributed throughout the structure to capture thermal effects. For a structure that sees significant temperature loading and thermal gradients, the temperature captured by the thermistors is essential to understanding the temperature-dependent strains. Furthermore, the thermal conditions affect the rate of creep and shrinkage, and thus also play a role in interpreting time-dependent results. As the structure age approaches 15 years, the as-built response indicates that the structure continues to creep. A temperature-adjusted age may be used to investigate the data under simulated constant temperature conditions, revealing a linear trend in deflections with the logarithm of time.