Estimation of the Load Sharing Ratio of Pre-installed Columns in Top-Down Buildings on Korean Rock

The estimation of the load sharing ratio of the pre-installed column in typical top-down method building was carried out using three dimensional finite element analysis. The main focus was on quantifying the apparent load sharing ratio of the prebored and precast pile–which is the common form of a pre-installed column – throughout the construction process. Additional parametric study was conducted based on series of numerical analysis with special attention given to the pile load sharing ratio under different pile array, pile embedded length, structure height and rock type. Moreover, the load sharing ratio of a single pile was investigated based on the relative location of the pile in the raft (footing). The numerical model was verified based on the field data of two actual construction site using the prebored and precast pile and the top-down method. Based on the analysis results, it was shown that the pre-installed columns of top-down method building is capable of supporting a notable portion of the structural load throughout the construction process. Furthermore, it was also shown that the pile near the center of the raft carried more structure load compared to the piles in the side and the corner.