CAIT project no.: 190 RU2705
Fiscal Year: 2006/2007
Rutgers-CAIT Author(s): Hani Nassif, Husam Najm, Nakin Suksawang, Rod Lewis
External Author(s): W. Lad Szalaj, NJDOT Research Project Manager
Sponsor(s): NJDOT, FHWA-USDOT
According to the American Society of Civil Engineers Report Card (ASCE, 2005), United States infrastructure received a grade point average of ―D‖ (i.e., poor rating) in 2005. Moreover, the National Bridge Inventory (Federal Highway Administration, 2004) revealed that of more than 594,470 bridges in the US, about 150,981 (25.4%) are considered structurally deficient or functionally obsolete. Hence, major decisions must be made to allocate the limited funds available for repair, rehabilitation, and replacement. The vast majority of deficient bridges will require at least partial or full concrete deck replacement.
Accordingly, many state departments of transportation expend significant effort and resources on the construction of durable reinforced concrete bridge decks. Previous research indicates that the development of transverse cracking in newly constructed concrete bridge decks continues to be a nationwide problem. In this study, three potential causes of cracking are investigated: 1) excessive restraint of the placed concrete, 2) design for deflection, and 3) high-strength gain of the concrete. Various bridge types were considered and modeled using the finite element (FE) computer program, ABAQUS. The FE model included the effect of shear studs, concrete strength, live load on the placement of concrete in existing bridges, and deflection limits. Existing data and results from this research indicate that the shear studs, concrete strength, and rebar locations have very little effect on bridge deck cracking. Depending on concrete pouring sequence, construction scenarios, and truck weight spectra, loading from adjacent truck traffic may lead to bridge deck cracking. To control bridge deck flexibility that causes an increase in concrete tensile stresses, new bridges with high-strength steel in excess of 70 ksi need to be designed with NJDOT deflection limits.