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Commentary on the Flat-Jack Test – Factors Influencing the Measurements
The paper presents the results of several flat-jack tests conducted on large sections of brick walls prepared in a laboratory. The influence of two basic factors was studied – the shape of the flat-jacks and distance between them – on the magnitude of the recorded strains. The three most common flat-jack shapes (semi-circle, rounded-rectangle and rectangle) were used for that purpose. The aforementioned spacing adopted for the purpose of the test was 3, 5 and 7 layers of bricks forming the analyzed brick wall specimen. Both of these factors have a significant impact on the boundary conditions of the test and the recorded results. For the purpose of comparison, brick prisms of a height corresponding to the spacing of the flat-jacks were cut out of the tested walls. The entire walls and then the cut out prisms were subjected to a load with a compressive force in order to estimate the modulus of elasticity E of the brick wall. Comparison of the values obtained shows that the semi-circle flat-jacks widely used in engineering practice might overestimate the rigidity of the wall tested. The reason seems to be the small surface area of this type of flat-jack and insufficient depth of its placement inside the wall bed joint. Only rounded-rectangle and rectangle flat-jacks allowed for estimating results that were more similar to those recorded in the other tests on masonry. Double flat-jacks testing allows for a minor-destructive assessment of the deformation parameters of the outer layer of brick wall. The recorded values were comparable with the results obtained by other authors.
Commentary on the Flat-Jack Test – Factors Influencing the Measurements
The paper presents the results of several flat-jack tests conducted on large sections of brick walls prepared in a laboratory. The influence of two basic factors was studied – the shape of the flat-jacks and distance between them – on the magnitude of the recorded strains. The three most common flat-jack shapes (semi-circle, rounded-rectangle and rectangle) were used for that purpose. The aforementioned spacing adopted for the purpose of the test was 3, 5 and 7 layers of bricks forming the analyzed brick wall specimen. Both of these factors have a significant impact on the boundary conditions of the test and the recorded results. For the purpose of comparison, brick prisms of a height corresponding to the spacing of the flat-jacks were cut out of the tested walls. The entire walls and then the cut out prisms were subjected to a load with a compressive force in order to estimate the modulus of elasticity E of the brick wall. Comparison of the values obtained shows that the semi-circle flat-jacks widely used in engineering practice might overestimate the rigidity of the wall tested. The reason seems to be the small surface area of this type of flat-jack and insufficient depth of its placement inside the wall bed joint. Only rounded-rectangle and rectangle flat-jacks allowed for estimating results that were more similar to those recorded in the other tests on masonry. Double flat-jacks testing allows for a minor-destructive assessment of the deformation parameters of the outer layer of brick wall. The recorded values were comparable with the results obtained by other authors.
Commentary on the Flat-Jack Test – Factors Influencing the Measurements
RILEM Bookseries
Endo, Yohei (editor) / Hanazato, Toshikazu (editor) / Łątka, Dawid (author)
International Conference on Structural Analysis of Historical Constructions ; 2023 ; Kyoto, Japan
Structural Analysis of Historical Constructions ; Chapter: 46 ; 568-580
RILEM Bookseries ; 47
2023-09-04
13 pages
Article/Chapter (Book)
Electronic Resource
English
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