As part of an innovation project funded by the FHWA Highways for LIFE program, a full-depth precast, ultrahigh-performance concrete (UHPC) waffle deck panel and appropriate connections suitable for field implementation of waffle decks were developed. After a successful full-scale validation test on a unit consisting of two panels with three types of connections under laboratory conditions, the waffle deck was installed on a replacement bridge in Wapello County, Iowa. The subsequent load testing confirmed the desirable performance of the UHPC waffle deck bridge. With lessons from the completed project and outcomes from a series of simple and detailed finite element analyses of waffle decks, a design guide was developed to help broaden the design and installation of the UHPC waffle deck panel cost-effectively in new and existing bridges. This paper describes the waffle deck design introduced in the guide as it is applied to new bridges. To minimize the cost of this new bridge deck system, information on maximum rib spacing and simplified connections, along with the design of the deck panel for positive and negative moments, is presented.

Many bridges in the United States are classified as structurally deficient and many others are nearing the end of their design service life, necessitating robust and durable bridge rehabilitation methodologies. States’ department of transport have recently developed innovative solutions for accelerated bridge construction using Ultrahigh Performance Concrete (UHPC) as grout material between prefabricated bridge components or as an overlay over existing bridge decks to increase their service life. The normal strength concrete (NSC)-UHPC interface behavior is critical in determining the overall performance of such NSC-UHPC composites. In this study, an experimental investigation was performed to quantify the effect of surface preparation and interface reinforcement on NSC-UHPC interface performance. The results from this study were compared with the current design guidelines for estimating interface shear capacity. In general, it can be concluded that increasing roughness depth and reinforcement area has a positive effect in interface shear capacity.

The use of UHPC as an overlay and repair material in the bridge industry has been increasing recently. Ensuring sufficient interface shear strength between the substrate and UHPC is necessary for adequate performance and the structural integrity of the composite section. Due to the lack of structural design code for UHPC members, designers often rely on experimental data developed by researchers or on existing conventional concrete design code to predict the interface shear capacity of sections containing UHPC. The various test methods currently used to quantify the interface shear strength oftentimes produce different results. The objectives of this paper are to create a database of the studies on the interface shear strength of UHPC members available in the literature and carry out a statistical assessment. Moreover, a reliability analysis is conducted on the collected experimental database, and the probability of failure is determined for UHPC–concrete, UHPC–UHPC, and monolithic UHPC interfaces. The paper also investigates the dependence of the reliability index on two different test methods used for interface shear capacity prediction. Additionally, a simpler interface shear capacity model with readily determined parameters is proposed for the monolithic UHPC interface, with a better reliability index compared to current design specification.