National Concrete Pavement Technology Center

Project description

The Georgia Department of Transportation (GDOT) employed Accelerated Bridge Construction (ABC) technology to reduce construction impacts and delays when replacing the State Route 299 bridge at I-24 in Dade County, Georgia, over a single weekend in May 2017. Self-Propelled Modular Transporters(SPMTs) were used for the bridge replacement. A few months after the replacement, GDOT observed a large number of visible cracks on the bridge deck. This study investigates possible causes of deck cracking observed on the SR299 bridge at I-24 in Dade County, Georgia. The research team has documented the distress observed in the SR299 bridge by creating a crack map, studying the material compositions, and conducting a finite element analysis. Design and construction details associated with thermal restraints are studied. In addition, displacements and forces imposed on the cast-in-place concrete bridge deck are studied. The main goal of this research is to establish a decision matrix for determining possible causes of cracking in the skewed bridge decks used for ABC, leading to the development of solutions to eliminate or reduce such cracking and recommendations for preventive measures. It is concluded from this study that skewed decks are more susceptible to cracking than straight decks due to asymmetric expansion and contraction. When skewed deck geometries exist in a semi-integral abutment bridge, the skewed corners on the abutment sides are vulnerable to developing cracks, regardless of the bearing details at expansion joint locations. Therefore, when designing a skewed bridge, a semi-integral abutment design should be avoided, if possible. If such design is necessary in conjunction with ABC technologies, bearings require greater consideration in order to minimize cracks resulting from temperature changes. Asymmetric thermal movements should be expected when an asymmetric deck geometry exists; thus, bearings and steel reinforcement in the deck must be designed accordingly.