Simulation of Excessive Deformation of Piping Due to Seismic and Weight Loads

The ASME Code for seismic design of piping system was revised in 1994 based on evaluation of pipe component test results submitted by the Piping and Fitting Dynamic Reliability Program (PFDRP). PFDRP indicated piping component failure to result in most cases from fatigue with ratchet. Excessive progressive deformation was noted by this program to ultimately occur in test #37, #39 and #40 piping models. This mode of failure was considered due to superposition of bending moment arising from vertical load produced by weight and horizontal seismic inertia force. To clarify the conditions leading to such failure, elastic-plastic dynamic analysis using the general-purpose FEM Code was carried out on the test#37 piping model of PFDRP. The analytical model and method were verified as effective means of study by comparison of analytical results with those obtained experimentally. The parameter determinations were made under condition of variation in dead weight stress and excitation and its dominant frequency. 1994 ASME seismic stress limits were shown effective for preventing excessive progressive deformation in tests #37, #39 and #40.Copyright © 2002 by ASME