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ELASTIC PROPERTIES OF MASONRIES NDT and MDT methods

ELASTIC PROPERTIES OF MASONRIES NDT and MDT methods. Past Experiencies New Research Activity Future Activities of GEOCISA. Past Experiencies.

francesca-ross
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ELASTIC PROPERTIES OF MASONRIES NDT and MDT methods

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  1. ELASTIC PROPERTIES OF MASONRIES NDT and MDT methods Past Experiencies New Research Activity Future Activities of GEOCISA

  2. Past Experiencies • Test specimens of representative dimensions on-site and compressive tests in laboratory to determine the modulus of elasticity of the masonry • Flat Jack, mainly in external collaboration

  3. CASE STUDY- CHURCH OFSANTO TOMÁS DE VILLANUEVA IN ZARAGOZA. ORIGINS: • Collapse of a Vault. • Cracks. • Moisture. WORK PERFORMED: • Determination of the origin of the collaps. • Structural assessment of the rest of the vaults. Mechanical characteristics of the masonry.

  4. CASE STUDY- CHURCH OFSANTO TOMÁS DE VILLANUEVA IN ZARAGOZA. Determination of the mechanical caracteristics of the masonry. STEP 1 • Drilled cores of bricks and mortars. STEP 2 • Test Samples of the brick fabric.

  5. CASE STUDY- CHURCH OFSANTO TOMÁS DE VILLANUEVA IN ZARAGOZA. Drilled cores of brick and mortar. • Compressive tests under failure, dry and wet: 19 cored samples of bricks y 6 of mortar:  40 mm and length 36-59,6 mm. • Correction of the experimental data for ressistance referred to a core of 100x100 mm (EC6) • Analytical determination of the ressistance and deformability of the masonry with different models: EC-6, Ohler, Hendry y Malek.

  6. CASE STUDY- CHURCH OFSANTO TOMÁS DE VILLANUEVA IN ZARAGOZA. Test samples of brick masonry. • 6 compressive tests, 3 with different moisture conditions. • Automated data acquisition with LVDT's. • The modulus of elasticity is determined by the load-deformation-grafics (about 1/3-2/3 of the failure stress). • The failure stress has been determined dividing the maximal load through the average cross section of the sample.

  7. CASE STUDY- CHURCH OFSANTO TOMÁS DE VILLANUEVA IN ZARAGOZA. Results

  8. CASE STUDY- CHURCH OFSANTO TOMÁS DE VILLANUEVA IN ZARAGOZA. Input data for structural modelling.

  9. New Research Activity • Flat Jack: Calibration of the proceeding of Flat Jack testing, analysing some aspects: - geometrical and mechanical characteristics of the Flat Jack - calibration test of the Flat Jack - slot preparation. • Hole drilling: Applicability on masonries, first results on stone-specimen. Correlation with Flat Jack measurements. • Sonic methods: Applicability of Impact-echo method on masonry structures.

  10. Flat Jack - Geometrical and mechanical characteristics • Flat Jack dimensions depending on the brick/stone dimensions of the masonry • Deformation of the Flat Jack during the tests • depends on the applied load • depends on the Flat Jack thickness • is remanent and the original thickness cannot be restored

  11. Flat Jack – Calibration test Proceeding of calibration • The deformation of the Flat Jack changes with the material of calibration and the applied load a flat jack calibrated with steel/specific load should not be used for testing on masonry

  12. Flat Jack – Preparation of the slot • The geometry of the slot is equal to the geometry of the Flat Jack cutting with a saw of same dimensions guided with a supported plate with rails. • The slot should be made in the mortar joints and removing all material/inserting shims to achieve a direct contact between the Flat Jack and the bricks/stones of the masonryfill the space with a mortar or other material

  13. Hole Drilling method-experimental work Methodology: • placing of the strain gages in a circle of 4cm diameter of the concentric center, at 0º, 90º and 225º • connecting the strain gages to a strain-rcoerding instrument by soldadura con estaño de hilos de cobre • drilling a hole of  = 3,6 cm and a depth of 3,6 cm • registering of strains

  14. Hole Drilling method-analytical work Residual stress  service stress:  = angle between the direction of max to the direction of r A, B: calibration constants considering the strain measurement in a finite area and material properties (E, ), can be obtained by • Calculation depending on the material properties of the material (E, ) from laboratory tests • Calibration experiment on the masonry test specimen, measuring strains before and after applying a load

  15. Test specimen 1: Sandstone masonry wall (217x182x30 cm) with stones of 30x30x60 cm • Compression of about 20 Kg/cm2 with 4 hydraulic Jacks hold on the metallic frame • Rigid beam over the test specimen to apply a uniform pressure distribution

  16. Hole Drilling Test Stone masonry in laboratory

  17. Hole Drilling-First results • Hole Drilling determined load with 20% error • The strain measurements follow an assymptotic function because of the heating of the gages • Calibration constants A, B determined experimentally

  18. Impact-echo • Applicability on tests specimens (WP8) for trainig the methodology and correlation with E-modulus • Applicability on pilot sites (WP10) of different typology, different materials and damages or other problems

  19. Future Activities_WP8

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