Flexural Performance of a Continuous Circular Tube Girder Bridge

This study introduces a continuous pedestrian-bridge design utilizing a circular tube girder and brackets for extended spans. The flexural performance evaluation in the negative moment region focuses on the support section of the continuous pedestrian bridge. In this regard, a full-scale test unit of the negative moment region was fabricated for a loading test. The test unit consists of a circular steel-tube girder, loading plates, vertical steel plates, and support. Subsequently, a finite element analysis (FEA) was employed to compare with the loading test results. The experimental and FEA results showed that the stresses in the members of the proposed pedestrian bridge are within the allowable stresses under service load. However, local buckling was observed in the circular steel-tube girder adjacent to the vertical steel plate under ultimate loading. To prevent the local buckling in the girder and improve the flexural performance of the negative moment region, a parametric study was performed by increasing the filling ratio of concrete inside the girder. The load–deflection relationship of the parametric study indicates that filling the negative moment region of a circular steel tube with concrete has a structural effect. Consequently, based on these results, an optimal filling ratio for the proposed bridge is suggested.