Construction stage analysis of a post-tensioned segmental crosshead

Abstract

In the construction of post-tensioned segmental crosshead, the stresses in the crosshead vary in every stage of the construction as the addition of new segment increases the bending moment while post-tensioning of tendon reduces it. Furthermore, the bending moment in the crosshead during construction is not balanced as new segment are added at one side of the cantilever at a time together with other construction load that operates on the same side of the new segment. In this paper, a study was conducted with finite element method to investigate the response of various parameters and effect of construction sequences on a segmental crosshead erected by balanced cantilever method. For this operation, a segmental crosshead model was generated using a finite element software and it was analyzed with various construction sequence. The rate of changes in stresses in each stages of construction was investigated and it was found that the stresses were over the limit when construction stage analysis was performed. In addition to that, it was also found that the maximum design moment for pier design can only be obtained by a more rigorous construction stage analysis.