Seismic behaviour of brickwork chimneys in buildings

Abstract

The construction of chimneys of solid bricks in buildings with sloped roofs was commonplace in Bulgaria for almost a century. The collapse of a chimney during an earthquake could potentially lead to damages greatly exceeding the loss of the chimney itself, e.g. partial damage to the roof tiling and leaks, as well as material damage, injury or loss of life due to debris fall. A FEM model was created, in which the storeys of the building are represented in a generalised way, while the chimney is modelled explicitly as a cantilever supported at roof level. The internal forces in chimneys with heights ranging from 0.5 m to 2.0 m, belonging to buildings with height ranging from two to seven storeys were computed. Acceleration records from real earthquakes acting at the base of the building with varying peak ground acceleration and predominant period were used for input loading. The maximum tensile stresses at the bed joints were computed and were compared to the typical tensile strength of the mortars used for chimney construction, to assess the possibility of collapse. A simple, low-tech method for upgrading of existing chimneys by applying a coat of cement-based plaster with embedded fiberglass mesh is proposed.

Mesh reinforcement in masonry mortar coatings: a systematic literature review

“…Numerical study on the structural behavior of masonry vaults under seismic activity [33] JP Finite element analysis of chimneys' structural behavior under seismic activity [18] JP Study focused on analysis of insulation materials [34] JP Study focused on the evaluation of insulation plaster [35] CP Part of a wider study already included [36] JP Reinforcement in horizontal joints, not coating [37] JP Method for concrete structure reinforcement [29] 0 : CP: conference paper; JP: journal paper. Coating thickness (mesh position) (mm) 5 Ref.…”

“…Visible cracking results from the propagation of microcracks along paths of lower resistance in the cementitious microstructure, and the mesh wires act as resisting cores since more energy is needed to pass through its surroundings, restraining the opening and propagation of cracking [14,15]. Also, the reinforcement distributes stresses along the mortar layer [14,[16][17][18][19], and may be used to enhance the bonding with the masonry or between multiple layers to reduce the risk of coating spalling and falling due to the high specific surfaces of the meshes [20]. Microstructural understanding of the reinforcements is also very important, since the mortar's rheology and reinforcement's geometrical features, as well as the chemical compatibility between them, are strongly connected to the bonding and behavior of the composite [21].…”