Static and seismic behaviours of innovative hybrid steel reinforced concrete bridge

Bridges using rolled steel H-section seem to be economical compared with plate girder bridges due to lower material and fabrication cost in the short-span length. The rolled steel H-section is a compact section and no stiffener is necessary. However, as the maximum available web height of the rolled H-sections is 900 mm, the applicable span-length is 20-25 m. A new composite girder bridge was proposed using rolled steel H-section to extend the span-length. The superstructure consists of continuous rolled steel H-girders composite with the RC slab, and the substructure is RC piers. The girder and the pier are rigidly connected by concrete and reinforcements to resist large negative bending moment at the joints. Experiments were conducted with the partial SRC bridge model, which showed that the proposed structure with a rolled H-girder had high ultimate strength with good ductile property, and attained the full plastic moment. A FE model was established considering material non-linearity and shear transfer between steel and concrete and compared with the experiments, which showed good agreement and clarified the load transfer mechanism. A trial design with the SRC highway bridge was carried out, confirmed that the applicable span length can be extended to 50 m. Seismic performance of the SRC system was verified by dynamic analysis, showed sufficient strength and ductility for strong earthquake with peak acceleration of 810 m/s2. Cross beams were eliminated in the new SRC bridge because the girder height was low, which was verified by FEM analysis with the full bridge model.