Hybrid FRP-UHPFRC composite girders: Part 2 - Analytical approach

A companion paper shows the experimental testing and numerical analysis of composite girders consisting of hybrid carbon/glass fiber-reinforced polymer (HFRP) I-girders topped with precast ultra-high-performance fiber-reinforced concrete (UHPFRC) slabs. This paper presents derivations of analytical equations to examine the composite behavior of the HFRP-UHPFRC girders with varying levels of interaction at the slab/girder interface. The derived equations to predict interfacial slip strain, curvature, and deflection of the composite girders were validated by the experimental data. An equation to determine the effective moment of inertia of the HFRP-UHPFRC composite girders with partial interaction is proposed and compared against the experiment. A fairly good agreement between the experimental and analytical results was found. The derived/proposed equations can simply and reliably evaluate the composite behavior between the HFRP I-girder and the UHPFRC slab.