Effects of Temperature Distributions on Thermally Induced Behavior of UHPC Shear Key Connections of an Adjacent Precast Prestressed Concrete Box Beam Bridge

Recently, there has been a rapid increase in using ultrahigh-performance concrete (UHPC) in bridge connections due to its high compressive strength, pre- and postcracking tensile strengths, superior bond, and durability characteristics. However, the behavior of field-cast UHPC connections under temperature effects is not yet fully understood. Furthermore, the temperature distribution that produces the largest thermally induced stresses in UHPC connections is unknown. In this study, the thermally induced stresses in field-cast UHPC shear key connections in an adjacent precast prestressed concrete box beam bridge were investigated using field data as well as a three-dimensional finite-element (FE) model. The FE model was validated using field data and exhibited the ability to capture the behavior of the bridge. A new temperature distribution was noticed based on the data analysis. This temperature distribution has not yet been considered by professional bridge design specifications, although it produced the largest thermally induced stresses in UHPC connections and at the beam-key interface. The observed temperature distribution should be considered in the design of UHPC shear keys for these types of bridges.