Interface Shear Performance of Full-Scale Composite UHPC Box Beams

  • Huaian Zhang (Lehigh University)
  • Clay Naito (Lehigh University)


A new ultra-high-performance concrete (UHPC) composite beam section was developed for use on short-span bridges in Pennsylvania. Due to the shallow nature of the section, interface shear strength plays a significant role in the design of the system. In order to enhance the horizontal shear capacity between the UHPC precast beam and cast-in-place (CIP) conventional concrete deck, either increase the stirrups at interface or an intentionally roughened top flange surface of the UHPC beam are considered. Due to the rheology of UHPC, conventional scoring techniques are not effective in creating adequate roughness. Therefore, keyed surface on the top flange which serves as the intentionally roughed surface is proposed in this study. Two designs for the connections between the concrete deck and the UHPC beam are presented and compared. It was found that the design with keyed surface reduce the usage of interface stirrup by 92%, therefore is preferred and selected for further investigation. Two composite UHPC box beams will be experimentally investigated in the future study. Different factors affecting the horizontal shear capacity of the composite UHPC beam will be discussed, namely, the geometry of keyed surface, and effective interface reinforcement details.

Keywords: UHPC, full-scale composite beam, keyed connection, horizontal shear

How to Cite:

Zhang, H. & Naito, C., (2023) “Interface Shear Performance of Full-Scale Composite UHPC Box Beams”, International Interactive Symposium on Ultra-High Performance Concrete 3(1): 33. doi:

Rights: © 2023 The Author(s). All rights reserved.

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Published on
04 Jun 2023
Peer Reviewed