Failure Mechanisms Governing Fatigue Strength of Steel–SFRC Composite Bridge Deck with U-Ribs

Abstract

A composite bridge deck system with steel fiber-reinforced concrete (SFRC) is an effective solution to the fatigue cracking problem of steel orthotropic decks. The governing fatigue failure modes were investigated by experiment and numerical simulation in determining the fatigue failure criteria and fatigue strength of steel–SFRC composite deck. Wheel running tests of a large-scale composite orthotropic deck were referred to obtain the fatigue stress and observe the failure mode sequence. A three-dimensional numerical model was then established and verified for the composite deck to attain the unfavorable fatigue stress range for each fatigue criterion under varying variables regarding SFRC overlay, steel deck, and headed studs. The parametric studies showed that the SFRC overlay cracking primarily governs the fatigue strength, and the thickness and flexural strength of SFRC overlay are crucial parameters. The SFRC with high flexural strength of at least 10 MPa is recommended to apply in the thin overlay with less than 100 mm thickness, and the common SFRC can be used with the overlay thickness of at least 120 mm for the orthotropic steel deck configuration in the common range of the design parameters.