Experimental Validation of a 10-m-Span Composite UHPFRC-Carbon Fibers-Timber Bridge Concept

This paper presents the experimental study of a new structure for a 10-m-span bridge deck, which takes into account the range of possibilities offered by new and high-strength materials along with the advantages of a traditional environmental friendly material. This 10-m-span element is formed by wooden beams braced at their ends on supports, a thin (7-cm-thick) upper slab made of precast ultrahigh performance fiber-reinforced concrete (UHPFRC), and fiber-reinforced polymer at the lower chord of these beams. The test program has been aimed at identifying the major critical aspects involved in producing an initial estimate of safety margins as well as validations of the design process and its underlying assumptions. Under the first loading configuration derived from live traffic loads, both the transverse and local bending of the thin UHPFRC slab were activated and confirmed by means of a three-dimensional finite-element computation. The second loading configuration corresponds to pure global longitudinal bending, with the bearing capacity being monitored up to the theoretical ultimate limit state loading and then beyond, up to experimental failure. Critical mechanisms and safety factors have also been identified. Though concept feasibility has been demonstrated, some aspects still need to be further optimized in order to obtain greater ductility and safer control over failure modes and occurrences.