Structural Design of Culvert Joints

Findings and conclusions of experimental and computational studies are presented regarding the effect of longitudinal bending on joints in rigid (reinforced concrete) and flexible (corrugated steel and thermoplastic) culverts. Two joint types are examined – those releasing the longitudinal bending moments (denoted ‘moment-release joints’) like gasketted bell and spigot joints, and those transferring them (denoted ‘moment-transfer joints’) such as band connections. Structural design requires evaluation of the ability to transfer vertical shear force across moment-release and moment-transfer joints, longitudinal bending moments across moment-transfer joints, and for moment-release joints to accommodate rotations. Both field performance and laboratory experiments are used to evaluate the behavior of jointed pipe systems for four different diameters, two different cover depths, and response to surface loads in a variety of positions. Different approaches are investigated for analysis of the structural behavior of joints to determine thrust, moment and rotation across joints. One approach considering two beams supported by elastic springs is used to develop a simplified design procedure. A second design approach involves finite element analysis using beam-on-elastic-spring modeling. Design examples are presented, and preliminary tests of the capacity of three of the test pipes indicate that these products satisfy the structural design requirements being proposed.