Elastic equivalent frame model with deformable connectors to assess tunnelling-induced damage to masonry buildings

This paper introduces an efficient modelling approach for assessing tunnelling-induced damage in masonry buildings. The approach idealises the building as an equivalent frame, employing a flexibility-based beam element formulation to represent spandrels and piers, akin to the modelling strategy frequently used in earthquake engineering. In contrast to standard approaches, the proposed ‘equivalent frame model with deformable connectors’ (‘EQFdc model’) represents the connections between the piers and spandrels with 2D macro-elements instead of rigid offsets. The paper first presents the formulation of the connectors and their interactions with the frame and foundation elements. Then, a soil-structure interaction scenario from the literature is examined. Soil-structure interaction is modelled using a linear Winkler approach; tunnelling-induced greenfield displacements are specified as prescribed displacements to the soil-foundation interaction model. Following typical assessment practice, linear elastic behaviour is assumed in the analyses, where damage is categorised based on limiting tensile strains. The EQFdc model successfully reproduces the results from a 2D finite element linear elastic continuum model for soil-foundation tractions, building displacements, major principal tensile strain distributions and damage categories. The introduction of the deformable connectors mitigates the overestimation of building stiffness caused by the rigid offsets. These improvements may benefit numerous equivalent frame modelling applications.