Session: SE-09-01 Advanced Seismic Evaluation and Code - 1

Paper Number: 106247

106247 - Investigation of Ultimate Behavior of Elbow Pipes by Tensile Loading Tests in the Direction of In-Plane Bending 

Piping systems of nuclear power plants are designed so that the primary stress based on elastic analysis satisfies the allowable limits. Therefore, piping systems are sufficiently safe, however, the seismic margin in the design evaluation is smaller than that in the realistic case. In addition, due to the increase in the design basis earthquake ground motion, the primary stress in the design evaluation of some piping systems that were previously within allowable limits exceeded the allowable stress. Usually, in such piping systems, reinforcement work is often carried out in order to satisfy the allowable limits for the primary stress. Although these measures provide additional safety, it is important to clarify the realistic seismic margin of piping systems and to advance the development of evaluation methods based on elastic-plastic analysis because the design basis earthquake ground motion is expected to increase further in the future.

In this study, static tensile loading tests in the in-plane bending direction were carried out for elbow pipes, which are typical damaged parts in piping systems. The ultimate behavior of elbow pipes in which ductile fracture occurs was clarified through the loading tests and the stress and strain at which the elbow was damaged in the loading tests was compared with the design values.

Presenting Author: Ryuya Shimazu Central Research Institute of Electric Power Industry

Presenting Author Biography: Bachelor of Engineering in Engineering Systems (March, 2013)
University of Tsukuba, Ibaraki, Japan (2009 April - 2013 March)

Master of Engineering in Engineering Mechanics and Energy (March, 2015)
University of Tsukuba, Ibaraki, Japan (2013 April - 2015 March)

Central Research Institute of Electric Power Industry, Chiba, Japan (2015 April - present)

Authors:

Ryuya Shimazu Central Research Institute of Electric Power Industry
Michiya Sakai Central Research Institute of Electric Power Industry
Yohei Ono Central Research Institute of Electric Power Industry