What are the factors to be kept in mind while analysing a PVC pipe using caesar-II? What is the appropriate method to do long term analysis for PVC pipes?

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A pipe stress analysis for thermoplastic piping is not evident. The material has no linear elastic behaviour, there are no codes on thermoplastic pipe stress and the used calculation model in CAESAR II (3D beam elements) is not suited for the large displacements you will get (if above ground and long lengths).