Finite Element Analysis of Profiled High Density Polyethylene Stormwater Arches Under Live Loading

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Adams, Robert
Stormwater arch , Finite element analysis , Live loading , Shallow burial
The physical response of a profiled high-density polyethylene stormwater retention arch structure under shallow burial subjected to design truck loading was investigated, with an emphasis on finite element modelling of the soil-structure system. First, three-dimensional, geometric and materially nonlinear finite element analysis was used to model a physical test on an arch specimen prior to burial with the goal to develop and validate a structural model capable of simulating the response of the arch structure up to and past its ultimate limit state. The explicit three-dimensional geometry of the tested arch specimen was measured in detail using a laser scanner, and tensile index tests were carried out to calibrate a viscoplastic constitutive model. The analysis was capable of replicating the measured load-displacement response of the structure up to and past its ultimate limit state governed by buckling. Second, analysis of a previously conducted full-scale physical test of a single arch structure buried with 460 mm cover above the crown and subjected to cyclic design truck loading was carried out. Displacement measured in the first load cycle was notably higher than in subsequent load steps as the arch worked its way into position, which included the densification of the initially uncompacted gravel backfill and soil shear failure underneath the wheel pad. Time-dependent behaviour was noted under constant load holds, particularly during the first load cycle. The validated structural model was used in conjunction with a nonlinear, elastic-plastic soil model to explicitly model the laboratory setup and testing. The model was able to capture the behaviour of cyclic loading, including apparent stiffening of the soil-structure system after the first load cycle. It matched displacements and deformed shape at the start of the nominal design wheel load (71.2 kN) for all load cycles but was unable to match the measured results during constant load holds and at the larger partially factored design wheel load (90.3 kN).
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