UHV transmission technology has the advantage of high safety and reliability as well as high transmission efficiency

and it is a new technology with great development potential in recent years.The pipeline of the installation wire will generate the deformation because of the thermal expansion and contraction during the operation

so the expansion joint is required to compensate the displacement of the pipeline.There are many types of expansion joints

and the expansion joints of different structures have different effects on the pipeline.Therefore

it is particularly important to choose the appropriate type of expansion joint.In order to study the effect of expansion joint structure on the strength of UHV transmission pipelines

Caesar II software is used to analyze the flexibility of UHV transmission pipelines in the paper

and the stress distribution and reaction force are compared while the single axial expansion joint and the straight-pipe pressure balanced expansion joint are installed on the pipeline respectively.The results show that the primary stress of the pressure balanced expansion joint is larger than that of the single axial expansion joint

but the secondary stress is almost the same.The reaction force of the single axial expansion joint is much larger than that of the pressure balanced expansion joint.