Effects on a Bending Pipe Behaviour via Simple Pre-Loading for Considering Functional Limitations of Piping in Industrial Facilities

Abstract This paper investigates the effect of initial plastic deformation on the load-displacement relationship of elbow piping of different wall thicknesses made of elastoplastic material The same conditions are applied in the finite element analysis (FEA). Load tests results and FEA of elbow piping made of carbon steel were conducted when three cycles of sinusoidal input with frequency of 0.02 Hz were applied to one end of the piping. Analyses were performed for three types of piping with different wall thicknesses before and after plastic deformation. The effect of initial displacement on the load-displacement relationship was confirmed by loading test, and analytical investigations were also summarized. Then, Comparison of the test and analytical results confirmed that the basic load-displacement relationship could be expressed qualitatively, such as a decrease in yield load due to a decrease in primary stiffness caused by the amount of initial plastic deformation, but from a quantitative standpoint, errors were observed in the loads. The error rate of the maximum load when the specimen was pulled in the in-plane bending direction tended to decrease as the wall thickness increased, but the error rate of the compression of the specimen in the in-plane bending direction showed a completely different trend from that of the pulling.