RU2141635C1 - Method of dynamic tests of buildings and structures and gear for its implementation - Google Patents

Abstract

FIELD: testing equipment. SUBSTANCE: method and gear are intended for determination of dynamic characteristics and seismic stability of used buildings and industrial structures and for evaluation of quality of construction work on erected objects directly on construction sites. Vibrations of tested object are excited on natural frequencies by action of sequence of impact momenta of low power. Transmitters positioned on object measure vibrations and set time intervals between impact momenta. Measured vibrations are summed by amplitude and dynamic characteristics of tested object are determined by measured parameters of summary vibrations. Gear for implementation of method has at least one unit converting vibrations into electric signal that is mounted on object, shock device, register, former of electric synchronization pulse recording moment of impact momentum and unit controlling storage connected in series. Register of electric signal is manufactured in the form of analog-to-digital converter of electric signal and digital storage connected in series. Output of unit controlling storage is connected to second input of digital storage. EFFECT: simplified design, reduced time and expanded application field of proposed method of dynamic test of buildings and structures. 4 cl, 5 dwg

Description

 The invention relates to the test of building structures, in particular to the study of the dynamic strength and vibrations of their structures, and can be used to determine the earthquake resistance of existing buildings and industrial structures, as well as to assess the quality of construction work on the constructed objects directly on construction sites.

 A known method of dynamic testing of large-scale structures (RU N 2104508, class G 01 M 7/02, 02/10/98), according to which oscillations of the test structure are excited at their own frequency by the action of a sequence of shock pulses on it using vibration sensors mounted on the test structure, is measured the parameters of its vibrations and they are used to judge the dynamic characteristics of the structure.

 To increase the amplitude of free vibrations of a structure, the excitation of its vibrations by this method is carried out using a power exciter that generates a pulsed supersonic controlled gas flow in antinodes of the calculated form of natural vibrations, which leads to a complication of the exciter, increase its dimensions and require a lot of time. This method does not allow for an operational examination of buildings and structures, requires personnel to have special skills in controlling the exciter and to observe special safety measures when handling it.

 Closest to the invention in technical essence is a method for dynamic testing of buildings and structures (RU N 2011174, class G 01 M 7/00, 04/15/94), according to which oscillations of the test object at natural frequencies are excited by the action of a sequence of shock pulses on it, s with the help of sensors installed on the object, its responses are recorded, the time intervals between pulses are determined by the measured oscillation parameters and the dynamic characteristics of the object are judged.

 Excitation of the oscillations of the test object by this method is carried out by detonating the explosive charges of pulsed power exciters of a very complex design and significant dimensions. This method does not allow for an operational inspection of buildings and structures, requires special qualifications from personnel and compliance with special safety measures when handling explosives.

 A device for implementing a method of dynamic testing of buildings and structures (Nazin V. V. "The latest earthquake-resistant structures and reinforced concrete mechanisms for the seismic isolation of buildings and structures" .- M .: Stroyizdat, 1993, S. 95-96, Fig. 23), containing the device excitation of oscillations of the test object and installed on the object at least one unit for converting vibration into an electrical signal, connected in series with the recorder of the electrical signal.

 However, the excitation of the oscillations of the test object in the known device is carried out by means of a very bulky hydraulic jack equipped with a special system of instant release from horizontal effort, which complicates the testing process and does not allow for an operational inspection of buildings and structures.

 Closest to the invention in technical essence is a device for implementing the dynamic testing of buildings and structures ("Inspection and testing of structures": Textbook for universities / O. V. Luzhin and others; Edited by O. V. Luzhin. - M .: Stroyizdat, 1987, p. 181-182, Fig. 8.4). Like the present invention, it comprises an impact device for exciting vibrations of a test object and at least one unit for converting vibration into an electrical signal mounted on the object, connected in series with the electrical signal recorder.

 However, the known device when testing high-rise buildings and large structures allows you to obtain acceptable accuracy in determining the dynamic characteristics of the object only with a sufficiently large power shock device, which complicates the testing process and does not allow for an operational survey of buildings and structures. In the case of using a low-power impact device, the error in determining the dynamic characteristics of the object may turn out to be unacceptably large due to low noise immunity caused by the application of microseismic interference (for example, from a vehicle moving near the test object, from wind effects, to weak free vibrations excited by the impact device, from equipment operating at the facility).

 The technical result to which the invention is directed is a method of dynamic testing of buildings and structures, is to simplify, reduce time and expand the scope of dynamic testing of buildings and structures due to the allowable reduction in the amplitude of shock pulses while maintaining the required accuracy in determining the dynamic characteristics of the test object.

 Reducing the amplitude of the shock pulses allows the vibration of the test object to be excited using a simple design and small impact device, for example, by striking a test object with a suspended load weighing from 30 to 50 kg. As cargo, a container made of easily deformable material (rubber, rubberized fabric, tarpaulin, etc.) containing bulk filler (for example, sand) can be used. Hanging with a load is the easiest and most affordable way to excite vibrations. In this case, it is possible to easily change the spectral composition and duration of the shock pulse (by using various shock absorbing pads), the point of application of the load. This makes it possible to conduct mass operational surveys of buildings and structures during their operation in areas of dense urban development, does not require highly qualified personnel and special safety measures when handling an impact device.

 The specified technical result is achieved by the fact that in the method of dynamic testing of buildings and structures, including the excitation of vibrations of the test object at natural frequencies by exposure to it a sequence of shock pulses, measurement of vibration-responses using sensors installed on the object and the setting of time intervals between shock pulses, the effect is shock pulses of small amplitude, measured in time intervals between shock pulses, the oscillations are summed by amplitude, and the dyne cal characteristics of the test object is determined from the measured parameters of total oscillations.

 The technical result of the invention is a device for implementing the considered method is to simplify the design of the device due to the permissible use of a low power impact device while ensuring high accuracy in determining the dynamic characteristics of the test object.

 This allows you to use the device for the implementation of the considered method when conducting an operational survey of multi-storey buildings and large structures in the conditions of their operation, in particular in the presence of microseismic interference.

 The invention relates to a device for implementing the above method, the device comprising a shock device for exciting oscillations of the test object and installed on the object at least one unit for converting vibration into an electrical signal, connected in series with the recorder of the electrical signal, further comprises connected in series an electric sync pulse forming unit, fixing the moment of impact of the shock pulse on the test object from the shock device, and the control unit of the storage device, while the electrical signal recorder is made in the form of a series-connected analog-to-digital converter of the electrical signal and a digital storage device, and the output of the control unit of the storage device is connected to the second input of the digital storage device.

 In the particular case of the implementation of the device for implementing the method of dynamic testing of buildings and structures, the electric sync pulse forming unit is connected to the percussion device.

 In another particular case of the device, the electric sync pulse forming unit is made in the form of an additional unit for converting vibration into an electrical signal installed on the test object near the place of impact of the percussion device.

 These particular cases of the execution of the device claimed in the invention are equivalent in terms of the achieved technical result, but the appropriateness of using one or another of them depends on the convenience of their particular implementation.

 In FIG. 1 shows an example of synchronous recordings of fluctuations-responses of the test object when exposed to it by a sequence of seven shock pulses. The characters “x1” to “x5” in FIG. 1 shows the records of responses from five sensors installed on different floors of the building; at the top of FIG. 1 are marked with serial numbers and the dotted lines show the moments of impact of shock pulses.

 In FIG. 2 as a reference sample for comparison with the records of the total oscillations (total response) depicted in FIG. 3 shows synchronous recordings of the fourth response of the test object when exposed to it by a fourth shock pulse, marked in FIG. 1. As in FIG. 1, with the characters “x1” to “x5” in FIG. 2 shows response records from five sensors installed on different floors of the building.

 In FIG. 3 shows synchronous recordings of the total response of the test object when exposed to seven shock pulses, marked in FIG. 1. The characters from “x1s” to “x5s” in FIG. Figure 3 shows the total response records from five sensors installed on different floors of the building.

 In FIG. 4 shows a diagram of a particular case of the implementation of the device for implementing the method of dynamic testing of buildings and structures.

 In FIG. 5 shows a diagram of another particular case of the device for implementing the method of dynamic testing of buildings and structures.

 We will consider the possibility of carrying out the invention on the example of the implementation of the method of dynamic testing of buildings and structures when testing a multi-storey building subject to microseismic interference caused by the movement of a fairly intense flow of vehicles near it.

 Sensors are installed on one or several floors of the test object, with which they measure fluctuations-responses to impulse effects. With the help of a load suspended on the wall of a building (or held in hands), vibrations of the test object at natural frequencies are excited, causing shock pulses on it. The time intervals between pulses are selected in the range, for example, from 1.5 to 5 s so that the oscillations from the previous shock pulse are almost completely damped. The responses measured in the indicated time intervals are summed in amplitude, for example, using the device described below for implementing the method in question. The number of shock pulses is chosen so that in the total response the useful damped oscillations, while synchronously accumulating, significantly exceed the amplitude of microseismic oscillations, the influence of which due to their random nature during summation is minimized. Measuring the parameters of the total vibrations, one judges the dynamic characteristics of the object (for example, periods of natural vibrations of the building of the first, second and third tones, logarithmic decrements of attenuation, distribution of vibration amplitudes along the height and front of the building - vibration diagrams).

 Presented in FIG. 1 as an example, synchronous recordings of the responses of the tested twelve-story building were obtained by applying a sequence of blows to the supporting wall of the twelfth floor with a 40 kg bag made of artificial leather and filled with sand.

 The possibility of minimizing the distorting effect of microseismic noise due to their random nature during synchronous summation of responses and thereby the possibility of ensuring high measurement accuracy (with a very low power of the percussion device) is illustrated by figures 2 and 3. If you visually compare the records taken as the initial sample for comparison the fourth building response of FIG. 2 with the summary response records shown in FIG. 3 obtained by synchronous amplitude summation of the responses from seven shock pulses, it is easy to see that, for example, the “tail” of the total oscillations (in the interval from 2.1 to 2.8 s in the records in Fig. 3) received from each sensor , was largely "cleared" of microseismic interference.

 Thus, a positive effect is achieved from the application of this method, which consists in a significant simplification, reduction of time and expansion of the scope of dynamic testing of buildings and structures due to the allowable reduction in the amplitude of shock pulses while maintaining the required accuracy in determining the dynamic characteristics of the test object.

 A device for implementing the considered method of dynamic testing of buildings and structures (see Figs. 4 and 5) comprises a percussion device 2, an electric clock pulse generating unit 4 connected in series with a memory control unit 6 mounted on the test object 1, at least one unit 3 converting vibration into an electrical signal that is connected in series with an electrical signal recorder, made in the form of series-connected analog-to-digital Converter 5 The electrical signal, and a digital storage device 7, the control unit 6 memory device output coupled to a second input of the digital memory 7.

 In the particular case of the implementation of the device for implementing the considered method of dynamic testing of buildings and structures, the electric synchronization pulse generating unit 4 is connected to the percussion device 2 (see Fig. 4). In practice, the electric synchronization pulse generating unit 4 can be made in the form of a contact electric sensor consisting of two conductive plates, one of which is mounted on the percussion device 2, and the other on the test object 1 at the point of impact when the vibrations are excited.

 In another particular case of the implementation of the device for the implementation of the considered method of dynamic testing of buildings and structures, the electric synchronization pulse generating unit 4 is made in the form of an additional unit for converting vibration into an electrical signal installed on the test object 1 near the place of impact of the percussion device (see Fig. 5). In practice, the additional unit can be performed in such a way that when a striking device 2 strikes the test object 1, a short electrical pulse is formed at the output of this unit, the leading edge of which coincides with the moment of impact of the shock pulse.

 A device for implementing the considered method of dynamic testing of buildings and structures works as follows.

 Impact device 2 strikes at the selected location of the test object 1. At the moment of impact of the shock pulse, block 4 generates an electric clock (the shape of which can coincide with the shape shown in the upper register in Fig. 1), which is input to the memory control unit 6. At the same time, the unit 3 for converting vibrations into an electric signal perceives the response of the test object 1 and sends the corresponding response to the electric signal to the analog-to-digital converter 5 of the electric signal. From the output of the analog-digital converter 5 of the electric signal, a digital signal is received at the input of the digital storage device 7, corresponding to the response of the test object 1. The storage control unit 6 generates and sends a command to the digital storage device 7 for recording the digital signal in the summing mode. The summation mode provides for the arithmetic summation of digital data in the corresponding memory cells, starting from the first cell, in which the signals received at the input of the digital storage device 7 are recorded. Recording continues until the next command to the digital storage device 7 is received from the storage control unit 6. From this moment, recording is resumed in the same cells of the digital storage device 7, but at the same time, digital values corresponding to the response of the test object 1 to the next shock pulse from the shock device 2 are added to the digital values already contained in them.

 The total number of impacts on the test object 1 by shock pulses depends on the signal-to-noise ratio achieved during the accumulation of useful data, that is, on the achieved relative decrease in the level of random interference components present in the responses. By increasing the number of excitations of oscillations of the test object 1, it is possible even with small response amplitudes to achieve a practically acceptable signal-to-noise ratio for a given accuracy of determining the dynamic characteristics of the test object 1. In practice, it turns out to be sufficient to produce from 6 to 10 impacts on the test object 1 with shock pulses with using a cargo weighing 40 kg.

 Thus, due to the possibility of using a low-impact percussion device by increasing the number of impacts on the test object, simplification of the device design is achieved to implement the considered method of dynamic testing of buildings and structures while ensuring high accuracy in determining the dynamic characteristics of the test object.

 This allows using the device for the implementation of the considered method to conduct a mass operational survey of multi-storey buildings and large structures in the conditions of their full-scale operation.

Claims (4)

 1. A method of dynamic testing of buildings and structures, including the excitation of oscillations of the test object at natural frequencies by exposure to a sequence of shock pulses, measuring vibrations using sensors installed on the test object and setting time intervals between shock pulses, characterized in that the impact is carried out by small shock pulses the amplitudes measured in the time intervals between shock pulses oscillations are summed in amplitude, and the dynamic characteristics are tested An object is determined by the measured parameters of the total oscillations.  2. Device for dynamic testing of buildings and structures, containing a shock device for exciting vibrations of the tested object and installed on the object at least one unit for converting vibration into an electrical signal, connected in series with the recorder of the electrical signal, characterized in that it is connected in series with the formation unit an electrical sync pulse, fixing the moment of impact of the shock pulse on the test object from the shock device, and the control unit inayuschim device, wherein the electrical signal recorder is designed as a series-connected analog-to-digital converter and a digital electric signal storage device, and the output of the control unit memory device connected to the second input of the digital storage device.  3. The device according to claim 2, characterized in that the electric sync pulse forming unit is connected to the percussion device.  4. The device according to claim 2, characterized in that the electric sync pulse forming unit is made in the form of an additional unit for converting vibration into an electrical signal installed on the test object near the place of impact of the percussion device.

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