Dynamic properties of a steel-UHPC composite deck with large U-ribs: Experimental measurement and numerical analysis

Steel-ultra-high-performance concrete (UHPC) composite decks, which are composed of thin steel- UHPC layers and large U-ribs, are an innovative bridge deck system. In this study, experimental and numerical approaches were combined to investigate the dynamic properties of a steel-UHPC composite deck. A large-scale steel-UHPC composite deck specimen was fabricated and tested under hammer impacting. The effects of the impact force characteristics on structural vibrations and noise were evaluated, and the vibration transmission characteristics in the deck were explored. The experimental results revealed that the steel-UHPC composite deck with large U-ribs exhibited complicated dynamic properties in different frequency bands. A finite element (FE) model was built and validated through comparison with the experimental natural frequencies and frequency responses. FE analysis was then used to compare the steel-UHPC composite deck with two other bridge deck systems (a conventional orthotropic steel deck and a steel-concrete composite deck). The numerical results indicated that the thin UHPC layer guaranteed the stiffness of the steel deck plate in the low-frequency range. At frequencies above 200 Hz, the vibration energy of the conventional orthotropic steel deck was approximately 0.45 times that of the steel-UHPC composite deck. Two countermeasures for reducing vibration (i.e., adjusting the crossbeam spacing and filling the large U-ribs with plain concrete) were found to be effective. Based on the simulation results, filling the U-ribs with plain concrete was the most effective approach and reduced the vibration energy by an average of 285% in the center frequency range of 63-1600 Hz.