A method for efficient numerical simulation of masonry under centric/eccentric and/or cyclic biaxial loading derived from near-realistic small-scale experimental tests – Extension, enhancement and validation of the unit-cell-methodology for plain and strengthened masonry

• Applicant: Professor Dr.-Ing. Oliver Fischer
• Subject Area: Structural Engineering, Building Informatics and Construction Operation ; Applied Mechanics, Statics and Dynamics
• Term: since 2017
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 325493675

In the first funding period, the methodological basis was developed to realistically characterise the load-bearing behaviour (under static-monodirectional or cyclic in-plane shear-compression-loading, which acts either in the mid-plane of the wall or eccentrically) of masonry made of small-format bricks and to represent it numerically accurately. It could be shown that the innovative unit-cell test setup (periodically recurring elements of a wall: bricks, bearing, longitudinal and butt joints) of TUM, which was further developed in the project, can also be used effectively with its compact test specimens to systematically analyse the complex damage behaviour of a small-format masonry with solid bricks. The validation and comparison with large-scale shear wall tests could not be fully completed in the first funding phase only for the eccentric load application (off-centre slab support). In the second funding phase, therefore, supplementary eccentric unit-cell and shear wall tests are to be carried out. In addition, small-format perforated bricks (centric/eccentric) will be included in addition to the solid ones considered so far; due to the orthotropic properties, significant changes in load transfer and damage mechanisms are expected compared to solid brick masonry. In addition, different wall thicknesses and brick arrangements are to be considered in order to be able to evaluate influences from theses parameters in the unit-cell tests more precisely for the first time. Finally, an attempt will be made to realistically represent the load-bearing behaviour of strengthened walls with the small-scale test setup. The numerical model will be further developed for the additional questions addressed and validated on the basis of the new experimental findings obtained. The planned additional fibre-optic sensors (e.g. in the mortar joints) will provide valuable additional information on the complex load-bearing mechanisms and enrich and further improve the simulation model. After successful completion of the project, a scientifically validated methodology and a simulation model will be available which, on the basis of the unit-cell approach, allow realistic predictions to be made of the load-bearing and damage behaviour of a wide variety of small-format masonry in existing buildings (made of solid or perforated bricks, various types of brick arrangement) under monotonic/cyclical, centric or eccentric shear-compression loading. Hereby, a much more flexible and powerful tool is available compared to large-scale tests (storey-high shear walls) to realistically assess existing buildings in terms of their behaviour under a wide range of loading scenarios. In addition, configurations that have not been dealt with so far can be added to the overall methodology comparatively easily.

• DFG Programme: Research Grants