Development of Reliability-Based Load and Resistance Factor Design (LRFD) Methods for Piping
8 Load and Resistance Factors
The main objective of this report was to develop reliability-based Load and Resistance Factor Design (LRFD) methods for piping, more specifically for Class 2∕3 piping for primary loading that include pressure, deadweight, seismic and mechanical loading. The LRFD methods were developed based on structural reliability theories, on previous practices in the design of pipes, and on LRFD rules and specifications adopted by other related structural codes. In these developments, commonly used design equations for piping were collected from various sources and investigated in terms of their limitations, applicability, uncertainties, and biases. The probabilistic characteristics of the basic random variables for both the strength and the load were quantified based on statistical analyses of data collected, on values recommended in other studies, and occasionally on sound engineering judgment.
The report provides results based on the following tasks: (1) a state-of-the-art assessment and selection of reliability theories, (2) review and evaluation of existing strength models for piping, (3) selection of strength models and equations deemed suitable for LRFD development, and (4) preliminary analysis of basic random variables to characterize their uncertainties.
The report also presented the detailed development work for LRFD methods of structural design for piping.