Development of Hygro-Mechanical Finite Element Model for Shrinkage Simulation of Prefabricated Building Facades

Prefabricated lightweight foamed concrete building facade can improve the energy efficiency of buildings and reduce the carbon emission of transportation. However, it is essential to maintain the dimensional stability of the... [ view full abstract ]

Prefabricated lightweight foamed concrete building facade can improve the energy efficiency of buildings and reduce the carbon emission of transportation. However, it is essential to maintain the dimensional stability of the full-scale element. One of the major problems with foamed concrete is the high shrinkage, which can be 10 times greater than that of conventional concrete. In this paper, a coupled hygro-mechanical model for simulating the drying-shrinkage behavior of the foamed concrete is presented. The drying-induced changes of the disjoining and capillary pressures in the pores are modeled by Kelvin law, while the transport of moisture is described by the classic Fick’s second law of diffusion. The strength of concrete under multiaxial states of stress can be evaluated by Ottosen’s four-parameter yield criterion. The incremental stress-strain constitutive relationship of the hygro-mechanical model was derived for incorporating it into general finite element subroutine. The model parameters were calibrated by the drying shrinkage data. The calibrated model demonstrated the cracking potential of three typical reinforced concrete panels of three different foamed concrete design mixes. It was found that the corner regions of the formworks have the fastest rate of moisture loss and the resulted drying-shrinkage is also the largest at those regions.  For Type III formwork with a window opening, another closed crack path is formed around the window opening but with the smaller crack width compared with that of the outer crack path.