Bridge Deck Cracking and Composite Action Analysis

According to the American Society of Civil Engineers (ASCE) Report Card, the US infrastructure received a grade point average of D (i.e., poor rating) in 2005. Moreover, the National Bridge Inventory (NBI) (Federal Highway Administration, 2004) stated that of more than 594,470 bridges in the United States, about 150,981 (25.4%) are structurally deficient or obsolete. Major decisions must be made to allocate the limited funds available for repair, rehabilitation, and replacement. An investment of at least $1.6 trillion is needed in the next five years to alleviate the problems. Accordingly, many State departments of transportation expend significant effort and resources on the construction of durable concrete bridge decks. Existing data and current research indicate that specific modifications to construction procedures, materials, and design details can significantly reduce the degree of cracking in bridge decks and thus reduce exposure of reinforcing steel to the corrosive effects of deicing chemicals as well as decrease freeze-thaw damage. A great deal is known about the factors that affect cracking in bridge decks, and what is needed is to implement this knowledge and monitor deck performance. However, there is need to fully understand the effect of various design parameters that are related to bridge cracking behavior. To study the cracking behavior of bridge decks, a detailed 3D FE model will be developed. A general-purpose finite element program, ABAQUS, will be utilized to derive the model. ABAQUS includes a variety of routines that allow for defining specific material models and provisions, such as concrete cracking and tension stiffening models, reinforcing steel rebar, boundary conditions, bond behavior (e.g., shear studs) and interaction between the reinforcing steel bars and concrete, and its mechanical properties. In addition, early-age cracking is often associated with material properties of concrete, especially concrete mixes that have high early-age strength development or high shrinkage performance. Furthermore, the FEM results will be validated using field results from various sources including those developed at Rutgers University and relate the possible cause of cracking on the bridge decks (e.g., thermo-stresses, heat of hydration, shrinkage, and live load). Once the model is validated and calibrated using field and laboratory measurements, the parametric study on modifying the design procedure can be carried out. The results of this research will add to that knowledge and will lead to reduction in bridge deck cracking, an improvement in durability, and an increase in the useful life of bridges.