Analysis of barrette foundations subjected to mechanical and thermal loads

In recent years, there has been increasing interest in the use of rectangular barrette foundations for the structural support and energy supply of tall buildings when circular piles become inefficient or uneconomical. In such applications, so-called energy barrettes are equipped with pipe heat exchangers to harvest shallow geothermal energy and thus undergo both mechanical and thermal loads while they structurally support the building. The mechanics of energy barrettes is currently poorly characterized, and analyses and designs of such foundations typically require time-consuming numerical simulations. This paper has a twofold objective: (1) provide a fundamental understanding of the mechanics of energy barrettes subjected to mechanical and thermal loads and (2) describe an analytical approach that can expediently model the vertical deformation of such foundations. This study indicates that the mechanics of rectangular barrettes under both semi-floating and end-bearing conditions is similar to that of circular piles with an equivalent diameter. From this perspective, an analysis approach is proposed to expediently address the vertical deformation of rectangular barrettes by modeling them as equivalent circular piles.