EP2622318A1 - Système de tube-manchon et procédé de test des murs de maçonnerie irréguliers - Google Patents

Système de tube-manchon et procédé de test des murs de maçonnerie irréguliers

Info

Publication number
EP2622318A1
EP2622318A1 EP11776545.3A EP11776545A EP2622318A1 EP 2622318 A1 EP2622318 A1 EP 2622318A1 EP 11776545 A EP11776545 A EP 11776545A EP 2622318 A1 EP2622318 A1 EP 2622318A1
Authority
EP
European Patent Office
Prior art keywords
tube
jacks
holes
wall
displacement
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP11776545.3A
Other languages
German (de)
English (en)
Inventor
José Luís FERREIRA DA SILVA RAMOS
Francisco Manuel Carvalho Pinto Fernandes
Paulo Mateus Mendes
Leandro Nuno Martins Vieira Marques
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Universidade do Minho
Original Assignee
Universidade do Minho
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Universidade do Minho filed Critical Universidade do Minho
Publication of EP2622318A1 publication Critical patent/EP2622318A1/fr
Withdrawn legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N3/08—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces
    • G01N3/10—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces generated by pneumatic or hydraulic pressure
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M5/00—Investigating the elasticity of structures, e.g. deflection of bridges or air-craft wings
    • G01M5/0041—Investigating the elasticity of structures, e.g. deflection of bridges or air-craft wings by determining deflection or stress
    • G01M5/005—Investigating the elasticity of structures, e.g. deflection of bridges or air-craft wings by determining deflection or stress by means of external apparatus, e.g. test benches or portable test systems

Definitions

  • the invention relates to a method for inspection and diagnosis for masonry elements within structures. More specifically, it relates to a non-destructive or minor- destructive method for detection of mechanical characteristics (stresses, deformability and strength) in the area of preservation of irregular masonry.
  • the present invention relates to a new method and system to analyze the pressure (or stresses), the deformability (Elastic moduli) and strength of masonry or adobe structural elements.
  • the Tube-jack testing method is used to detect the existing compressive stress in masonry elements.
  • the tube-jack system consists of a number of tube-jacks connected in parallel, with an number of linear voltage displacement transducers measuring the displacement of the masonry near the line of the tube-jacks, that when inserted into holes drilled in a stressed masonry element, and inflated with a fluid like air, water or oil, expand to the size of the holes, and provide the necessary stress and displacement measurements to calculate the existing local compressive stress, the deformability and whenever possible, the strength of the masonry.
  • This invention is characterized as being highly applicable to historical and heritage constructions containing masonry or adobe structural elements with large and irregular stone units and nonlinear mortar joints because of the method's use of small diameter tube-jacks that can be inserted in masonry joints, preventing damage to the historic masonry units in the inspection and diagnosis of the structure.
  • the present invention describes a ystem for mechanical testing of irregular masonry walls (1) comprising:
  • tube-jacks (2) a plurality of elastically inflatable tubes, herein referred as tube-jacks (2), suitable to be inserted into holes (11) of the wall (1) to be tested;
  • the pressure generator or generators (14) are able to inflate and expand diametrically the tube-jacks (2) .
  • the fluid is air, water or hydraulic oil.
  • the tube diameter is 20 - 40 mm.
  • a preferred embodiment further comprises displacement transducers (12) able to measure displacement of the wall (1) in the direction of the compressive stress caused by an expansion of the tube-jacks (2) .
  • the displacement transducers (12) are LVDTs.
  • the present invention also describes a method for mechanical testing of walls (1) comprising the steps of:
  • tube-jacks (2) inserting a plurality of elastically inflatable tubes, herein referred as tube-jacks (2), into holes (11) of the wall (1) to be tested;
  • the fluid is air, water or hydraulic oil.
  • the holes (11) are positioned in the mortar between the masonry units.
  • the holes (11) are positioned in the path of the joints between masonry units, regardless of the straightness of the path.
  • the holes (11) are positioned in a path approximately linear and perpendicular to the assumed line of compressive stress in the masonry elements.
  • the holes (11) are positioned 50
  • the displacement transducers (12) are positioned approximately perpendicular to the line of tube-jacks (2) and parallel to the assumed direction of compressive stress in the masonry elements.
  • the displacement transducers (12) are LVDTs.
  • the holes (11) are through holes (11) ⁇
  • Masonry structures of all types can fall into disrepair or become damaged by natural or human actions. In order to design the most appropriate and effective interventions necessary to preserve a masonry structure, determination of mechanical characteristics of the structural masonry elements is often necessary. If the masonry structure is of historic value, it is often the case that techniques which induce a minimal amount of damage to the structure are preferred in order to preserve as much of the irreplaceable structure as possible.
  • flat-jack testing is known as a relatively non-destructive technique among the various types of tests that can be performed on a masonry structure.
  • the primary goal of conducting an in- situ flat-jack test is to determine the existing mechanical properties of the masonry such as the local compressive stress and deformability .
  • this test is usually performed on structural elements such as walls and columns.
  • the devices required for flat-jack tests are easy to move and use and it is possible to obtain results concurrently with the performance of the test.
  • a number of masonry units may also be subject to unwanted partial damage. Due to these damages, additional repair to the masonry in the tested area will be required once the testing is concluded. Furthermore, utilization of the equipment used to cut the slit for the flat-jack can be cumbersome, and, at times, multiple cuts are required to attain a suitable opening to install the jack.
  • JP58097636 refers to a simple flat- jack device used to determine the Young's modulus in concrete.
  • the concept is the same as the previously described flat-jack where the jack is embedded in the concrete, a stress is induced in the concrete by inflating the jack with oil, and the measurements of the displacement of the concrete and pressure in the jack can be used to determine the Young's modulus.
  • This device and procedure have the same issues as previously described by the flat- jack and also do not solve the issue of damaging masonry units during a test on irregular masonry.
  • a second document, CN101419143 refers to a device that can perform a bidirectional composite stress loading test on a brick body. While this may be useful for determining the characteristics of a single masonry unit, it does not solve the issues related to determining the stress in a structural masonry element and does not provide a method that produces limited damage on the masonry units.
  • the document ITRM960219 refers to a cylindrical jack that can be used to determine the modulus of elasticity of the masonry.
  • the method uses a diamond coring machine to make the first hole in the masonry.
  • This device consists of a tube with a rigid layer and flexible layer. Oil or another substance is pumped into the flexible layer. The deformation of the masonry between the two layers is measured to determine the modulus of elasticity.
  • the present invention comprises both an in-situ testing method for determining mechanical characteristics of any kind of masonry (i.e., masonry with regular or irregular units and mortar joints) and the developed jacking component of the system, the tube- jack.
  • the tube- jack component consists of a tube closed at one end and fitted with a connector at the other end (See #2 in Figure 5) .
  • the tube When injected with air, water or oil through the connector end, the tube is able to inflate elastically - and expand diametrically.
  • the use of air is preferable to water or oil because of its cleanliness in the case that the tube fails.
  • the tube-jack consists of a hollow device that is filled with a fluid that can be pressurized and used to inflate the space and induce a pressure on the surrounding material.
  • the tube-jack differs in equipment compared with flat-jack.
  • the flat plate, pressurized with oil, in the flat-jack system is replaced with a desired number of tubes, with the possibility of pressurization with air or an alternative fluid, in the tube-jack system.
  • the utilization of tubes on irregular masonry walls eliminates the need to create straight slots which may cause partial damage to the masonry units and a high undistributed stress along the slot.
  • the tube- jacks inserted into the holes can be instrumented with strain or other deformability sensors at different positions, allowing the collection of information about the contact stress distribution throughout the length of the hole.
  • the new system allows for the testing of multi-leaf walls (i.e. walls compose by different stone arrangements in the external surfaces and a different internal core) because the holes can be done in the complete thickness of the walls. It also produces less drastic changes in the stress distribution around the openings and leaves less damage on the tested area, which is the most desirable advantage of this system.
  • Drilling is according to an embodiment a preferred method but other suitable ways to create a hole ih a wall may be used, dependant on wall materials, thicknesses, etc...
  • the first step in the tube-jack testing method is positioning the holes and measuring the initial distance between target points on the masonry wall and between the holes.
  • the following task is drilling the holes in the masonry element where the tube-jacks will be inserted.
  • the holes are drilled in the mortar between the stone units and can be located simply by following the path of the joints regardless of the straightness of the path as shown in Figure 1. In the case of adobe walls, the holes can be at the most convenient points, without any specification.
  • the line of tube-jack holes should be substantially perpendicular to the assumed line of compressive stress in the masonry element, for optimum results.
  • the tube-jack system permits the freedom to follow the path of the joints and eliminates the need to cut in inappropriate locations and damage the masonry units (See Figure 2) . This is one of the most significant innovations. Numerical analysis showed that it was appropriate to locate the holes at an equal spacing of approximately 50 to 125mm (but other distances may be appropriate dependant on materials, thicknesses, etc..) in order to ensure adequate space for drilling and placing of the tube-jacks and to have the tube-jacks close enough to each other to produce a relaxation of the masonry in the line of the tube-jacks for measuring the displacements .
  • LVDTs or similar transducers used to measure the displacement of the masonry element before and after the tube-jack holes are made and during the inflation of the tube-jacks, are positioned on the surface of the masonry element in an embodiment approximately between the specified locations for the tube-jack holes. In another embodiment they are individually positioned along an approximately perpendicular line to the line of tube-jacks and parallel to the assumed direction of compressive stress in the masonry element (See Figure 4) . They shall be preferably installed prior to drilling the holes and beginning the test in order to measure the distances before the test begins. All of the used transducers, including those specified for measuring the pressure of the air, water or oil in the following sections, shall be preferably connected to the same data acquisition system, which can consist of a computer with hardware components connected by USB cables.
  • Displacement transducers are available in numerous formats and types - electrically resistive or capacitive, optical, ultrasound, etc... - any suitable to the purposes above described .
  • tube-jacks are inserted into the holes. It is recommended to insert the tube-jack immediately after drilling the holes and removing the mortar so that mortar surrounding the hole is not allowed to fill the hollow space. If additional deformation occurs after the tubes are placed in the holes, the flexibility of the tubes will bear the deformed shape of the cross-section of the hole. Thus, the tubes must be flexible, but strong enough to support high pressures. Tube diameters are preferably between 20 and 40 mm (but other diameters may be appropriate dependant on materials, thicknesses, etc..) .
  • the test be conducted as soon as possible after formation of the holes so as to avoid material relaxation around the holes and compressive cracks, vertical cracks parallel to the direction of the compressive stresses.
  • air, water, or oil must be pumped into the tubes by means of conventional equipment.
  • an air compressor can be used to pump air into and inflate the tube-jacks.
  • All the tube-jacks are preferably connected in a parallel system and therefore will inevitably have the same internal pressure, but independent pumps may be used provided care is taken to ensure the pressure is substantially the same between tube-jacks.
  • the pressure level can be controlled manually or automatically and is measured with a pressure gauge and/or transducer located between, or at, the tube- jacks and the pump/air compressor (See Figure 5) .
  • the tube- jacks are inflated until distances between measured reference points on the surface of the masonry element, on either side of the jacks and in the direction parallel to that of the compressive stress where the LVDTs were placed, retain their original values before drilling, within a tolerance specified by the technician performing the test.
  • the measured value of the pressure in the tube-jacks at this point can be used to determine the compressive stress in the masonry element.
  • Eq. 1 depicts the formula used to calculate this stress (am) .
  • am Km Ka p ( 1 )
  • 0 ⁇ Km ⁇ 1 is the jack correction factor (also known as calibration factor)
  • 0 ⁇ Ka ⁇ 1 is the area correction factor
  • p (psi or MPa) is the jack pressure required to recreate the original opening, as marked by the reference points, within the allowed tolerance.
  • the jack correction factor is the ability of the tube to be inflated; with value of 0 representing a tube that cannot be inflated and a value of 1 representing a tube that can be expanded without any increase in pressure. This value is provided by the manufacturer.
  • a similar procedure is carried out to determine the Young's Modulus of the masonry, the double tube-jack test.
  • a second row of holes in an approximately parallel mortar joint to the first row, is located and drilled.
  • Tube-jacks are placed in both rows of holes and connected in parallel to the air compressor or water or oil pump.
  • LVDTs are positioned perpendicular-to the tube- jack hoses and between the two lines of holes. Measurements of the displacements and pressures are recorded as the pressure in the tube-jacks is increased and pressure is subsequently applied to the masonry between the rows of tube-jacks.
  • the load-displacement relationship is monitored during the test and used to determine the Young's Modulus and possibly extrapolate the compressive strength of the masonry. When the relationship becomes nonlinear, indicating the failure load is approaching, the test is stopped. Loading and un-loading cycles can also be performed .
  • Figure 1 Represents drilled holes (11) on a sample wall for a single tube-jack test.
  • Figure 2 Represents general configurations for possible lines of holes (11) for tube-jack testing in irregular masonry
  • Figure 4 Represents a close-up view of several devices of the Tube-jack system including the LVDTs (12), the tube- jacks (2) and connection tubes (13) .
  • Figure 5 Represents a plan view of the tube-jack system set-up including a length of masonry wall (1), tube-jacks (2) inserted in holes drilled through the entire width of the wall, L and T-connectors for the piping system (3 and 4), pressure gauge (5), and connection (6) to air compressor or pump.
  • Figure 6 - Represents the modeled wall including boundary conditions and vertical loading .
  • Figure 7 Represents the stress distribution in MPa over the length (distance in mm) of the modeled wall after cutting a 40cm slit for a flat-jack test.
  • Figure 8 Represents the stress distribution in MPa over the length (distance in mm) of the wall after drilling 9 tube-jack holes over a length of 90cm.
  • Figure 9 Represents the pressure-relative displacement relationship in the Tube-Jack models when there is a 100 mm distance between holes for various diameters and for two different Young's moduli of the walls.
  • Figure 10 - Represents the modeled regularly aligned brick masonry wall including isotropic brick and mortar elements .
  • Figure 11 Represents the modeled irregular stone masonry wall including isotropic stone and mortar elements .
  • Figure 12 Represents the pressure-relative displacement relationship for the tube-jack test modeled in the irregular stone masonry wall .
  • Model embodiments were also constructed consisting of two isotropic materials, stone and mortar.
  • One model consisted of regularly aligned brick masonry and the other model of irregularly shaped stone masonry.
  • the brick or stone units had a mass density of 3000 kg/m3, Young's modulus of 50 GPa, and Poison ratio of 0.20.
  • the mortar properties consisted of a mass density of 1800 kg/m3, Young's modulus of 5 GPa, and Poison ratio of 0.20.
  • the masonry walls had a width of 2.50 m, thickness of 0.35 m and height of 2.55 m and were loaded with a distributed load equal to 14 ⁇ 10 ⁇ 4 N/m on the top of the wall to produce an average stress in the masonry of 0.40 MPa (the final stress state at the level of the tube-jacks also considered the self-weight of the wall), as shown in Figures 10 and 11.
  • the resulting stresses at the level of the tube-jacks produced by performing a phase analysis with these two models by varying the pressure in the tube-jack holes between 0 and 1 MPa, are very close to the theoretical values. In fact, correction factors were around 1.0 to 1.1 for both models.
  • the pressure-relative displacement results are shown for the modeled irregular masonry wall tube- jack test in Figure 12.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Chemical & Material Sciences (AREA)
  • Aviation & Aerospace Engineering (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Investigating Strength Of Materials By Application Of Mechanical Stress (AREA)

Abstract

Cette invention concerne un système et un procédé d'analyse de la pression (ou des contraintes), de l'aptitude à la déformation (modules élastiques) et de la résistance d'éléments de construction ou d'éléments structuraux en adobe (1). Ce système comprend plusieurs tubes-manchons (2), des éléments tubulaires extensibles, reliés en parallèle, et plusieurs capteurs de déplacement mesurant le déplacement de la construction près de la ligne des tubes-manchons ; ces capteurs, lorsqu'ils sont insérés dans des orifices pratiqués dans un mur ou un élément de construction soumis à une contrainte (1), et lorsqu'ils sont gonflés à l'aide d'un fluide, au moyen de raccords appropriés (3, 4, 6) reliés à un générateur de pression, se dilatent jusqu'à atteindre la taille des orifices et permettent alors d'obtenir les mesures nécessaires de contrainte et de déplacement, et de calculer à l'aide d'un contrôleur de pression (5) la contrainte de compression locale existante, l'aptitude à la déformation et, lorsque cela est possible, la résistance de la construction. Le système selon l'invention peut s'appliquer aux édifices historiques et patrimoniaux contenant des éléments de construction ou des éléments structuraux en adobe et comportant des pierres de taille importante et irrégulière et des joints de mortier non linéaires.
EP11776545.3A 2010-10-01 2011-10-03 Système de tube-manchon et procédé de test des murs de maçonnerie irréguliers Withdrawn EP2622318A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
PT10532110 2010-10-01
PCT/IB2011/054333 WO2012042510A1 (fr) 2010-10-01 2011-10-03 Système de tube-manchon et procédé de test des murs de maçonnerie irréguliers

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EP2622318A1 true EP2622318A1 (fr) 2013-08-07

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WO (1) WO2012042510A1 (fr)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2991048A1 (fr) * 2012-05-22 2013-11-29 Fbco Diagnostic non destructif, determination des caracteristiques des ouvrages par enregistrement et decodage du comportement sous un spectre de sollicitations choisi ou impose

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5897636A (ja) 1981-12-08 1983-06-10 Sakata Denki Kk コンクリ−トの応力測定法
GB2284669B (en) * 1993-12-07 1997-10-01 Strainstall Engineering Servic Determination of in situ stress in concrete
IT1285109B1 (it) 1996-04-04 1998-06-03 Carmen Maria Piccirilli "martinetto cilindrico" indagine deterministica per definire le caratteristiche meccaniche delle murature, che consente di agire su
CN101419143A (zh) 2008-11-21 2009-04-29 同济大学 砌体试件双向复合受力加载试验装置

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO2012042510A1 *

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WO2012042510A1 (fr) 2012-04-05

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