The importance of flat jack tests for masonry structures.
Understanding Structures: Measure before intervening. Decide with knowledge.
In masonry structures, what is not measured is merely estimated. And in existing buildings, often old, heterogeneous and lacking reliable construction information, properties estimation is not enough.
Flat jack tests in masonry are one of the most robust and insightful tools for understanding, in situ, the real behaviour of load-bearing walls. They make it possible to assess existing stress levels, deformability and load-bearing capacity directly on site, taking into account the true constitution of the masonry, its state of conservation, the presence of moisture and the actual loading conditions.
Unlike laboratory tests on extracted samples, which are inevitably altered in the process, flat jack tests act directly on the existing structure, providing quantitative, reliable and truly representative data on its structural performance.
This is a minimally invasive method, with localised and controlled impact, particularly suited to historic and heritage buildings, where preserving structural integrity is a fundamental principle. When correctly planned and executed, these tests do not compromise either safety or the overall performance of the wall.
More than a test, flat jacks are a decision-making tool.
The results obtained make it possible to:
- mechanically characterise existing masonry;
- identify structural vulnerabilities and the causes of damage;
- verify load-bearing capacity under new demands, such as changes of use or seismic actions;
- design structural strengthening with greater accuracy and reduced intrusiveness;
- calibrate numerical models and significantly reduce analytical uncertainty.
In a context where relying solely on bibliographic values often leads to excessively conservative solutions or, conversely, dangerously optimistic one, flat jack testing allows assumption to be replaced by knowledge.
Because better intervention in existing buildings does not mean intervening more.
It means intervening with information, judgement and responsibility.
NCREP. Engineering that measures, understands and decides.