Effects of Interface Roughness on Shear Key Performance of Ultra-High Performance Concrete in Adjacent Box Girder Bridges

  • Fouad T. Al Rikabi orcid logo (Ohio University)
  • Husam H. Hussein orcid logo (Ohio University)
  • Shad M. Sargand (Ohio University)


For decades, adjacent box girder bridges have shown good performance and service life. However, longitudinal joints connecting the adjacent box girders may be susceptible to a degradation, including cracking and debonding, under a large number of load and thermal cycles. Although ultra-high-performance concrete (UHPC) has been used for joints in the highway bridges to eliminate the longitudinal cracks in shear keys, there is limited information regarding the effect of bond strength between UHPC and high strength concrete (HSC) on the load transfer mechanism in the transverse direction between adjacent box girders. The aim of this study is to use experimental results and finite element (FE) analysis of direct shear tests to evaluate the performance of optimized shape of the UHPC shear key (OPT-UHPC). The FE models, along with three types of shear key roughness, were calibrated and validated with previously published laboratory experimental results by the authors. Three types of interface roughness (smooth, mid-rough, and rough) between UHPC and HSC components were employed to investigate the load transfer mechanism between concrete components. The results of numerical simulations of OPT-UHPC joint model using interface models with different roughness types were compared, the results of the analysis show that joint with a smooth surface is sufficient for load transfer between HSC components, and that joint with a mid-rough surface is capable of transferring load up to failure in the HSC components. The results can be used as a guidance when designing connection between adjacent box beams in bridges.

Keywords: interface bond, Ultra-high-performance-concrete, UHPC, HSC, Interfacial properties, Bridge connections, Finite element method, Shape optimization

How to Cite:

Al Rikabi, F. T., Hussein, H. H. & Sargand, S. M., (2019) “Effects of Interface Roughness on Shear Key Performance of Ultra-High Performance Concrete in Adjacent Box Girder Bridges”, International Interactive Symposium on Ultra-High Performance Concrete 2(1). doi:

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Published on
02 Jun 2019