Abstract
Pipeline that formed with flexible joints has a high safety to a differential settlement or a seismic displacement on soft ground by the effect of each joint reaction. However, buried pipe joints subjected to seismic motion on site have scarcely ever been investigated because of internal water or underground condition, so the behavior has not been clarified enough. This paper discusses the allowable range of joint for expansion and bending. In situ survey of earthquake-damaged pipelines and model shaking test were carried out. Results are summarized as follows:
1) Each joint in pipeline changes a joint gap due to the earthquake, but the mean value of them hardly shifts.
2) Initial gap or bending of joint hardly influences the seismic behavior.
3) The change of joint gap caused by the earthquake is particularly large beside the bend pipe or the structure, comparing with in the straight line.
4) The safety factor of a curved joint including initial gap is larger than a straight joint beside bend pipe.
