RU1779993C - Method for determining operational fitness of damaged reinforced-concrete structure reinforced with layer of new concrete - Google Patents

Abstract

The invention relates to non-destructive testing of material and structures and can be used in non-destructive testing of the quality of reinforced concrete structures reinforced with a layer of new concrete. The purpose of the invention is to increase the accuracy and performance of the suitability control of a structure. The design is subjected to local dynamic influences, fluid is supplied to the interface, acoustic emission (AE) signals are received, average frequencies of the received signals, as well as the energy of the transverse and longitudinal components of the AE signals that have passed the interface between the gain layer and the old layer are measured concrete before and after supplying fluid to the interface of the structure. The average frequencies of the AE signals determine the stress levels in the reinforcement layer and the layer of old concrete, the ratio of which determines the load-bearing capacity of the structure , by the ratio of the ratios of the transverse and longitudinal components of the received signals before and after the liquid supply, the adhesion quality of the old concrete layer and the reinforcement layer is determined. 2 ill.

Description

The invention relates to non-destructive testing of materials and products and can be used to determine the quality of previously damaged reinforced concrete structures used in construction and bridge building, reinforced with a layer of new concrete.

A known method for determining the suitability for further operation of reinforced concrete structures subjected to thermal stress, namely, that the structure is subjected to local dynamic action, the parameters of the emerging acoustic emission (AE) signals are measured, including the middle frequencies and energy of the AE signals, s

taking into account which the strength characteristics of the structure are determined, including the voltage level in it, by which the suitability of the structure is determined.

Closest to the invention is a method for determining the serviceability of a damaged reinforced concrete structure reinforced with a layer of new concrete, which comprises determining the bearing capacity of the reinforced structure and the adhesion quality of the reinforcement layer. with a layer of old concrete, which judges the suitability of the structure for operation.

However, the method is not sufficiently accurate and productive, since the assessment of the bearing capacity is based on the approximate

design and complex destructive tests of the specimens, and the adhesion quality is determined by visual inspection of the junctions of the reinforcement layer and old concrete of the structure.

The purpose of the invention is to increase the accuracy and performance of the suitability control of a structure.

The goal is achieved. that in the method for determining the serviceability of a damaged reinforced concrete structure reinforced with a layer of new concrete, which consists in determining the bearing capacity of the reinforced structure and the adhesion quality of the reinforcement layer to the layer of old concrete, by which it is judged that the structure is suitable for use, in the zones of greatest The stresses of the reinforced structure on the layers of old and new concrete carry out a local dynamic effect, receive acoustic emission signals in each layer of the structure, measure the average the frequency of these signals, which determine the stress levels in each layer, additionally locally affect one of the concrete layers of the structure, moisten the structure with liquid from the side of the impact until it penetrates into the mating zone, after wetting, they again act on the same concrete layer , on the opposite side of the structure, the transverse and longitudinal components of the acoustic emission signals are received, the energy of the components of the acoustic emission signals is measured, and their ratio is determined before and after wetting, o The structural bearing capacity is judged by the ratio of stress levels in the concrete layers, and the adhesion quality by the ratio of the energy ratios of the components of the acoustic emission signals.

Fig. 1 shows a schematic diagram of conducting stress measurements in old concrete of a structure and new concrete in a reinforcement layer; Fig. 2 is a schematic diagram for determining the adhesion quality of old and new concrete in a structure at their junction.

The diagram shows a repaired structure consisting of layer 1 of old concrete and reinforcement layer 2 of new concrete, interconnected by reinforcing metal rods 3, uniformly distributed over the area of the structure. On the surface of reinforcement layer 2 of new concrete and on the surface of layer 1 of old concrete, a standard receiving transducer 4 of acoustic emission signals of a common floor is connected to standard acoustic emission equipment (not shown). 5 designates a d-dowel shell for local dynamic impact on the surface

old and new concrete, 6 indicates the area of poor adhesion of old and new concrete.

Figure 2 further shows a receiving transducer 7 of transverse acoustic vibrations and a receiving transducer 8 of longitudinal vibrations. A method for determining the serviceability of a damaged structure reinforced with a layer of new concrete,

carried out as follows.

The structure, reinforced after repair with a layer 2 of new concrete and reinforcing metal rods 3, is installed in the place of the building specified by the project or

bridge and secured so that the structure can absorb the operational load. After that, tests of the structure begin to determine its suitability for further operation.

To do this, a standard receiving transducer 4 of acoustic emission signals is installed in the most stressed (calculated) area of the structure from the side of the old concrete layer and then using a local loading device, for example, a dowel-dowel 5. load with a force exceeding the concrete tensile strength. A series of AE signals resulting from this are received by the receiving transducer 4 and analyzed in the AE signal analysis unit of standard acoustic emission equipment. Then determine the average frequency of the appearance of AE signals in a given time interval, taking into account

which, according to the well-known formula, determine the value of static loading and in the control zone of the structure from the layer 1 side of old concrete

45

ai / Ri- X / J / IR + Ci2ln -gl,

where Ri is the tensile strength of the old concrete layer of the structure;

J / 1R, Ci, Ai - regression coefficients characterizing the dependence of fcp on Art. obtained during testing of samples of old concrete.

After that, the AE signal receiving transducer 4 is mounted on the structure from the side of the reinforcement layer 2 and, using a projectile-dowel 5, the new concrete layer is dynamically loaded with a gain exceeding the tensile strength of the new concrete. The resulting series of signal AEs are received by the receiving transducer 4 and analyzed using the same equipment. In this case, the average frequency fcp2 is determined by the occurrence of AE signals in a given time interval, taking into account the known formula for determining the static voltage ОЈ in the control zone of the structure from the side of reinforcement layer 2 of new concrete

02 / R2

/,

,

where R2 is the tensile strength of new concrete in the reinforcement layer;

2R.C2. A2 are registration coefficients characterizing the dependence of fcp on (7 obtained by testing samples from concrete reinforcement layer.

 The values of the regression coefficients are determined in advance by testing samples of old and new concrete structures based on a known technique. The stress ratio is then determined in the old concrete of the structure and in the layer of the new concrete of the structure. If the ratio O2 / cr 0, b is 0.9, then this means that the structure works as a unit t and the working voltage is uniformly distributed over the entire cross section in the most stressed zone of the structure. If the ratio is 8 - 0.9, then the structure cannot be considered suitable for further use, so -Zk the load will be unevenly distributed over the cross section and in the case of further operation, the load-bearing capacity of the whole structure may be lost, which can lead to its sudden destruction.

However, a ratio of 8 to 0.9 is a necessary but not sufficient condition for a final recognition of the suitability of the structure for further use. Therefore, after determining the Oila ratio, the stresses go over to estimating the adhesion value of the old and new concrete at the junction. For this purpose, two receivers 7 and 8 of acoustic emission signals are installed on the surface of the structure, for example, from the layer 1 side of new concrete, one of which is designed to receive the transverse component of AE signals, and the other is designed to receive the longitudinal component of AE signals (you can use the receiver total energy of the AE signals, since such a receiver receives the total energy of the longitudinal and transverse components of the signals).

0

5

0

5

0

5

0

5

0

Then, from the layer 1 side of the old concrete, with the aid of a dowel-dowel 5, a local effect is performed on the surface of the concrete, the value of which must exceed the strength of the concrete. Signals A3, arising from this and consisting mainly of longitudinal and transverse waves, propagate along the concrete, pass the interface between the old concrete of the structure and the layer of new concrete of the structure and are received by the receiver 8 of the longitudinal component and the receiver 7 of the transverse component.

Using standard acoustic emission equipment connected to the AE receivers, the average energies (or average amplitudes) of the transverse and longitudinal components of the received signals are measured and their ratio Esp1c / ECP1 is determined. Then, the structure, preferably from the side of the reinforcement layer 2, is abundantly watered with liquid (water) in order to create an obstacle for the passage of transverse waves of acoustic signals. After the concrete has been soaked with liquid to the mating zone, local dynamic action is again carried out with the help of a shell-dowel 5 on the concrete surface, the longitudinal and transverse components of the AE signals are received from the opposite side with the same receivers, and the average energy ratio Es2c / Esr2 is determined transverse and longitudinal components of the received signals. If the ratio of Esp2C / Esp2 decreases to a value less than (0.8 - 0.85) Esp1c / Esp1, this means that there is a gap in the mating control zone filled with liquid, which prevents the passage of transverse waves of AE signals. If the ratio of Esp2s / ECP | (018 - 0.85) Ecpic / Ecpi or remained unchanged compared to the previously changed ratio ECP1c / ECP1, this means that in this mating zone the adhesion quality is quite good.

In order to establish the suitability of the structure for further use, the adhesion quality is determined by the EU # mating area by performing the above measurements at several points of the structure and averaging the results. The conclusion on the suitability of the structure for further operation is made on the basis of two measured characteristics: the value of the ratio of stresses in the new and old concrete of the structure should be at least 0.8 - 0.8, and the value of the ratio ESr2c / Esr2 should be at least 0.80 - 0.85 of the previously measured.

Claims (1)

SUMMARY OF THE INVENTION A method for determining the serviceability of a damaged reinforced concrete structure reinforced with a layer of new concrete, the method comprising determining the load-bearing capacity of the reinforced structure and the adhesion quality of the reinforcement layer to the old concrete layer, which determines the suitability of the structure for use, characterized in that that, in order to increase the accuracy and productivity of the control, in the areas of greatest stresses of the reinforced structure on the layers of old and new concrete, local dynamic impact receiving signals of acoustic emission in each layer structure is measured by the average frequency of the signal, which is determined stress levels in each concrete layer, additionally locally affect one of the concrete layers of the structure, moisten the structure with liquid from the side of the impact until it enters the mating zone, after wetting, they again act on the same concrete layer, take the transverse on the opposite side of the structure and longitudinal components acoustic emission signals, measure the energy of the components of the acoustic emission signals and determine their ratio before and after wetting, the structural bearing capacity is judged by the ratio of stress levels in concrete layers, and the adhesion quality - by the ratio of energy ratios components of acoustic emission signals. L Lj 4 Figure 1 Editor V. Kuznetsova Compiled by S. Volkov Tehred M. Morgenthal Ry. 2. Proofreader M. Maximishinets