INVESTIGATION OF THE STRUCTURAL ADEQUACY OF C 850 BOX CULVERTS

The structural behavior of American Society for Testing and Materials (ASTM) C 850 box culvert sections resulting from live load was investigated using theoretical analyses, field testing, and model testing. The field testing was performed on box culvert sections that were put into service after testing. These box culvert sections were installed on state routes in Ohio using construction crews and normal construction procedures. An overview of these analyses is presented in this paper. The initial purposes were to determine whether shear connector plates are required to transfer the load across a joint between adjacent box culvert sections, and if the recommended maximum spacing of 30 in. was appropriate. Testing at the first site indicated that shear connector plates are not required to transfer the load. The primary purpose of testing at the second site was to verify the results from testing at the first site. Additionally, it was concluded that C 850 box culvert sections are overdesigned structurally. Before testing was undertaken at the third site, a redesign was executed for C 850 box culvert sections. The redesigned C 850 box culvert section was essentially the same as the C 789 design with 4 ft of earth cover and HS 20 loading. Testing at this site demonstrated that the redesigned C 850 box culvert section performed satisfactorily. The major conclusions are that shear connectors are not required on ASTM C 850 box culvert sections and that these sections are overdesigned structurally. It was also concluded that the deflection along an edge of the top slab was so low, even with the wheel load applied at that edge, that the AASHTO edge beam requirement need not be enforced.