Thermal Gradients In Segmentally Constructed Hollow Box Bridge Piers

Temperature-induced stresses in hollow concrete bridge superstructures such as those commonly used in precast segmental construction are well known and recognized by bridge design codes. However, very little is known about the effect of non-linear temperature gradients on hollow concrete bridge piers.

Strain gauges and thermocouples were installed in a segmentally constructed concrete bridge pier as part of an ongoing investigation of the construction and performance of the new U.S. 183 segmental viaduct currently being built in Austin, Texas. Temperature and strain data were acquired continuously over the course of the first four months of the pier’s service life.

Data concerning temperature gradients across the pier’s cross-section, thermally-induced strains, and post-tensioning stresses are presented. Temperature gradient data and the induced thermal strains are analyzed to determine the effects of temperature changes on the pier. Calculations with measured temperature data, including a finite element analysis, are also compared to those made with temperature gradients published in current bridge design codes. Comparisons of calculated and measured strains are made to confirm the accuracy of the calculation methods. Recommendations concerning design thermal gradients and the design of hollow concrete piers for temperature gradient effects are presented.