The input for seismic wave passage is in the form of applied soil strains. The soil strain obtained from the geotechnical-civil design is converted by the piping analyst into an equivalent temperature, as follows:
DT = e / α
Where DT is the equivalent temperature applied to the pipe model, e is the maximum soil strain due to seismic wave travel, and α is the coefficient of thermal expansion of the pipe.
Bentley used references 1 and 2 for performing verification/validation for buried safety related piping. Should this verification/validation include the alternative of using DT equivalent temperature? Is this method valid for buried piping analysis?
1. ALA, American Lifelines Alliance Guidelines for the Design of Buried Steel Pipe, 2001 with February 2005 errata.
2. ATS QA58 and QA 93
AutoPIPE ATS test system QA93 does incorporate the strain [calculated as 4.8E-4 in/in in paper by E C Goodling] due to seismic wave passage in the test system:
This procedure for calculating the soil strains due to seismic wave propagation and using an equivalent temperature rise to consider the effects has been published in numerous papers and standards1 in slightly different forms:
a. ASCE 4 – 98: Seismic Analysis of Safety-Related Nuclear Structures section 3.5.2 [Derivation of soil strains only]
b. A proposed design procedure for buried safety related piping at nuclear power facilities, Timothy M. Adams et. al., PVP-Vol. 360, Pressure Vessel and Piping Codes and Standards – ASME 1998 pp. 502
c. A review of methods for analysis of buried pressure piping, George Antaki, WRC bulleting 425
d. Non-mandatory appendix D – Non-mandatory seismic analysis method, Cases of ASME Boiler and Pressure Vessel Code, N-755-1 (July 15, 2011)
AutoPIPE provides the functionality of calculating this equivalent temperature rise due to seismic wave propagation for ASME B31.1 (2004 and later) and ASME NC/ND (2004 and later), however these calculations are not selected to be part our ATS currently.
Model Soil Properties with Soil Calculator and Underground Piping