Creep and shrinkage monitoring and modelling of CFST columns in a super high-rise under-construction building

Concrete-filled steel tube (CFST) giant columns have been widely used in super high-rise structures. However, there is a major shortage of field measurements of shrinkage and creep deformation from actual projects. Existing experimental results and derived models cannot reflect the actual on-site conditions where sustained loading is an incremental process during construction and the facing environments vary. In this study, the deformations of giant CFST columns in a super-high-rise under-construction building were monitored for more than 400 d. For comparison, a scaled experiment was conducted in a laboratory. The strains measured in the laboratory and on-site show a good changing trend over time and could be used for model verification. The existing CEB-FIP (2010) model is improved in two ways: 1) introducing a reduction factor in the calculation of shrinkage strains and 2) considering the stress history and stress redistribution in the calculation of creep strains. With parameters determined from the experimental results, the modified model could predict the shrinkage and creep strains of CFST columns in the actual project well with sufficient accuracy.