Session: OAC-06-02 Continued Safe Operation of Existing Assets-2

Paper Number: 123580

123580 - Critical Strain in Carbon Steel Pipes With Local Wall Thinning Subjected to Large Bending in Soil Liquefaction-Induced Lateral Spreading 

A buried pipeline may undergo large bending deformations due to lateral spreading induced by soil liquefaction during an earthquake. Furthermore, the deformability of the pipeline is influenced by local wall thinning, which can result from phenomena such as corrosion. Therefore, this study examined the bending fracture behavior and critical strain of wall-thinned pipes subjected to bending moments. Bending tests were conducted on straight pipes with wall thinning located in either the compressive or tensile side in order to obtain failure modes. The experimental results showed two failure modes: buckling and rupture. Buckling failure occurred on the compressive side without the occurrence of necking in the region with localized wall-thinning. Rupture failure occurred at the area of localized wall-thinning on the tensile side. Finite elements analysis (FEA) was performed to simulate the fracture behaviors observed in the bending tests. As a result, the critical strain of the pipe exceeded 30% equivalent plastic strain for buckling mode on the compressive side and exceeded 10% equivalent plastic strain for rupture mode on the tension side. Additionally, this study offers instances of acceptable wall-thinning sizes of pipelines subjected to large bending in liquefaction-induced lateral spreading, using the criteria of 30% equivalent plastic strain on the compressive side and 10% equivalent plastic strain on the tension side.

Presenting Author: Tomoka Homma Tokyo Gas Co., Ltd.

Presenting Author Biography: Tomoka Homma was born in Kanagawa, Japan. She entered Sophia University, Japan in the spring of 2014. She majored in Mechanical Engineering and received her Bachelor of Engineering Degree in 2018 and Master of Engineering Degree in 2020. After graduation, she went to work for Tokyo Gas Co., Ltd., in Tokyo as a research engineer. The area of her specialty is mechanical engineering.

Authors:

Tomoka Homma Tokyo Gas Co., Ltd.
Shoma Onuki Tokyo Gas Co., Ltd.
Yasuhito Imai Tokyo Gas Network Co., Ltd.
Masaki Mitsuya Tokyo Gas Co., Ltd.