Full-Depth Precast Concrete Bridge Deck System Phase II
Principal Investigator:
Cathy French, Professor, Civil Engineering
Co-Investigator:
- Carol Shield, Associate Professor, Civil Engineering
Project Summary:
The Minnesota Department of Transportation (Mn/DOT) Precast Composite Slab Span System (PCSSS) is an effective bridge system for short to medium span bridges (20-60 feet). The system consists of a series of 6-foot-wide, inverted, precast T-sections that are placed between supports. Cast-in-place (CIP) concrete is placed on top of the precast sections to form a monolithic slab span system. Engineers use reinforcement at the webs of the Ts and also place reinforcement cages between the precast webs in order to intersect any longitudinal cracks that may develop above the joint and between the adjacent precast flanges. Several of these systems have already been constructed and have been in service for up to three years. It is important to document the performance of these systems in the field by mapping any cracks that have developed and to correlate the cracks to the potential joint regions. Researchers will document the surface cracks on four of the existing PCSSS bridges, and will also review a sampling of cores taken from the bridges to evaluate the potential development of reflective cracks. The cores will be taken above the longitudinal joints and between the precast flanges. One of the early implementations of this bridge system (Center City Bridge) showed the development of cracking above the longitudinal joint, between the precast sections, and also at the pier. These cracks were detected with limited instrumentation in the CIP portion of the bridge and appear to be the result of thermal gradient effects. The strains at these locations have been increased annually. As part of this project, researchers will continue to monitor the sensors in the Center City Bridge. In addition, the investigators will review and comment on the latest design methods implemented by Mn/DOT for the PCSSS bridges, including the concept of designing the bridges as a series of simple spans rather than considering the effects of restraint moments.
Sponsor:
Project Details:
- Start date: 07/2009
- Project Status: Active
- Research Area: Infrastructure
- Topics: None