Compensation length of two-dimensional chloride diffusion in concrete using a boundary element model

Abstract

The boundary element method (BEM) has been widely employed in engineering practice. However, the BEM is not commonly used in numerical analysis of chloride diffusion in concrete and might yield unsatisfactory results if the time duration is significantly long for concrete exposed to chloride environment. In this work, we propose the compensation length of chloride diffusion in concrete, as well as the compensation coefficient based on the error function. The fundamental solution relevant to the governing partial differential equation is presented for chloride diffusion in concrete, enabling the development of the boundary element scheme. In particular, the two-dimensional diffusion analysis is investigated in detail by using the BEM model, featuring the proposed compensation length to achieve superior numerical results. Specifically, the time interval is sparsely discretized into several sub-domains in the BEM model, while the spatial domain is discretized along the boundary of the computational diffusion field, resulting in considerably fewer unknowns in chloride diffusion analysis. Several numerical examples are presented to demonstrate the effectiveness and accuracy of the BEM with compensation length and to illustrate excellent results using the 2-D BEM formulation for chloride diffusion near the intersection of exposed surfaces of concrete specimens.