Field testing and analysis during top-down construction of super-tall buildings in Shanghai

Abstract

Although certain measurements regarding super-tall buildings constructed using the top-down method have been published, new advances in top-down construction have been developed with the construction of super-tall buildings in China. This paper presents the theory of soil-structure interactions in pile foundations and extends it to the top-down construction method. Based on this theory, the forces and the deformation of the diaphragm wall, slab and soldier piles at various stages of construction can be computed. Two typical tall buildings of 60 and 37 stories with deeply embedded 4-level and 5-level basements located in Shanghai were used as case studies of the vertical displacements of their diaphragm walls and soldier piles, the deflections of the diaphragm walls, the earth pressures, and the rebar stresses during top-down construction. The values measured in the field agree well with the predicted values from soilstructure interactions theory and statistical-empirical formulas. Two additional super-tall buildings of 101 and 121 stories, in which the 4- level and 5-level basements and the main buildings are round, are discussed regarding their unique deformational characteristics. In addition, the diaphragm wall can serve a load-sharing function. These engineering case studies, including the comprehensive predictions of deformation based on field tests and estimates using statistical formulas, can improve tall building design.