Equivalent frame model for the assessment of tunnel-induced damage to masonry buildings

The risk of tunnel-induced damage to existing masonry buildings is typically assessed in current practice by either modelling the building as a simplified elastic beam or by more complex procedures involving three-dimensional numerical analysis. This paper describes a preliminary 'equivalent frame' (EQF) model, of intermediate complexity, which is currently under development for the analysis of tunnel-induced damage to masonry buildings. The EQF model comprises an assembly of specially-formulated EQF elements. Soil-foundation interaction behaviour is modelled with consistent one-dimensional finite elements, incorporating a Winkler soil model. The current EQF model employs linear elastic models for the building and the soil, and is limited to two-dimensional (2D) building geometries. A study is described in which the EQF model is applied to an idealized masonry facade founded on a strip footing. Tunnel-induced ground movements are prescribed via empirical models for greenfield displacements. Separate analyses are described, employing the finite element program DIANA, in which the facade is modelled as a mesh of 2D continuum finite elements. The EQF model provides distributions of tensile strain that indicate a good qualitative match with those obtained from the 2D continuum finite element analysis, although the EQF model demonstrates an overall stiffer response.