The Ultimate Capacity of Post-Tensioned Segmental Box Girder Bridges with Different Lengths of Segments: An Experimental Study

Abstract

The flexural behavior of precast concrete segmental box girder is significantly depends on the length of segments. This study aims to investigate the effect of segment length at different compressive strengths of concrete on box girder bridges. In this study, six beams divided into two groups with internal tendons having a constant span of 2400 mm and a different number of segments in each beam for each group were tested to failure to assess the flexural behavior of such bridges when subjected to pure bending under two-point loading. The samples were constructed using High-Performance Concrete (HPC), having a compressive strength of 43.3 and 78.6 MPa for groups 1 and 2, ten shear keys for each segment, four post-tensioning tendons, and a geometry closely resembling the keyed joints of actual segments. Each segmental beam was formed with a different number of segments and different span to depth ratios (L/D). Deflections at mid-span, first crack, concrete surface strains at specified locations, and ultimate load values were recorded during the test. All samples failed due to excessive force in tendons and close to the face of the joints at mid-span. Also, it was observed that segmental beams consisting of three segments with a span to depth ratio = 2.13 recorded greater ultimate load capacity than the other beams with two segments and four segments with = 3.2 and 1.6 in both groups. As for deflection at mid-span, in group1 for the beam with three segments, it was 2.13; the deflection was greater by 13 and 10.6 % than the beams with four and two segments, respectively. For group 2, deflection in the beam with three segments was greater by 4.9% and 19.4% than the beams with two and four segments, respectively.

Keywords: box girder bridge, flexural capacity, high-performance concrete, precast concrete girder bridge, segmental bridge.