Field Implementation and Monitoring of Bridge Approach Slabs

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CAIT project no.: 99 RU6676 slab

Fiscal Year: 2000/2001

Status: Final

Rutgers-CAIT Author(s): Hani Nassif, Nirali Shah

External Author(s): Nakin Suksawang, Florida International University, W. Lad Szalaj, NJDOT



Bridge approach slabs are designed to function as a transitional roadway to the bridge deck spanning the distance between the abutment and road pavement. However, the number of rough-riding approaches with heavy maintenance requirements is sufficient to convince highway agencies that a serious problem exists. The objective of this study is to implement and evaluate proposed design alternatives for bridge approach slabs under field conditions. Two design alternatives, Embedded Beam (EB) and Constant Thickness (CT), are implemented in the Doremus Avenue Bridge project. The study includes installation of sensors at various locations in bridge projects under contract and to verify the findings of the Phase I probable causes of cracking, location of cracks, factors influencing crack development, and to recommend new design alternative that could reduce or eliminate crack development in approach slabs. A field study is conducted and data is collected from field observations. Measured results were compared with those predicted by the finite element model to determine the reliability and the consistency of the model. Subsequently, several design alternatives were studied and compared to determine their effectiveness in reducing the possibility of crack development and tolerating higher vehicular loads. The embedded beam (EB) is recommended based on results from field observations and long term monitoring of their performance under normal traffic and environmental conditions. The new EB design alternative is adopted by the New Jersey Department of Transportation (NJDOT) as the detail for future use in the design of approach slabs.