RU2250444C2 - Method of monitoring bridge during use - Google Patents

Abstract

FIELD: measuring engineering.

SUBSTANCE: method comprises visual monitoring to indicate visible defects and instrumental monitoring by repeatable measuring deflections of bridge frameworks before use and during use, comparing the parameters, and estimating the bridge condition from the comparison. The method additionally comprises measuring parameters, which characterize the general stress-strain condition of the bridge structures, such as transverse and longitudinal movements of the bridge frameworks with respect to the piers, the longitudinal movements being measured in the units of bearing of the framework under the construction joints, deviation of bearing section, stress in the bearing sections of the frameworks and intermediate section of the frameworks, amplitude and frequencies of vibration of the frameworks, shrinking of the piers for solid frameworks, and deviation of the pier from vertical axis at the top. The threshold values are calculated for each parameter measured. The condition of the bridge is assessed from the comparison of the value of each measured parameter before and during use with the corresponding calculated threshold values. The measurements are carried out at least twice a year.

EFFECT: enhanced reliability of monitoring.

1 cl, 5 dwg, 1 ex

Description

The invention relates to measuring technique, namely to the study of parameters characterizing the state of the bridge structures during its operation, in particular to the measurement of its stress-strain state. The invention can be used to information support the decision-making process for maintaining the service properties of the bridge at the required level during the estimated life.

Known methods for monitoring the state of bridge structures based on visual inspection and the identification of defects and damage during their operation: deformation of the working elements of spans, the presence of corrosion and cracks, the condition of welds, etc. (Kirillov BC Operation and reconstruction of bridges and pipes on roads M., 1971).

The disadvantage of this method is the lack of information due to the receipt of information only on visible defects, the lack of efficiency in obtaining information at the moment. The long time period between inspections does not allow obtaining information about the current state of the bridge.

A known method of vibration diagnostics of operating road bridges, designed to assess the stiffness of spans, according to which measure the function of the dynamic deflection of the spans of the bridge (the amplitude of the forced vibrations under the influence of harmonic load). (Transport construction, No. 2, 2001, p.12-15).

However, this method, as a rule, is used before the start of operation of the bridge or when obvious defects appear that require inspection of the structural elements of the bridge by a specialized organization with subsequent dynamic testing. Measurement of only the vibration parameters of the bridge does not allow us to judge the state of the bridge as a whole.

A known method for monitoring the stress state of a continuous steel-reinforced concrete span of a road bridge, including determining the stress in the main beams by determining deformations in the extreme fibers of the belts of the main beams of the span at various stages of installation, testing and construction work. (Transport construction, No. 6, 1998, p.17-19).

However, this monitoring is carried out at the installation stage during static tests and is not carried out during the operation of the bridge. The parameters measured in this method are not sufficient to assess the current state of the bridge.

There is a method of measuring deflections when testing artificial structures, such as bridges, including installing deflections on the tested elements in a controlled section, attaching cargo deflection meters to one of the ends of the wire ties and immobilizing their free ends. At the same time, stretch marks are fastened to the supports of the test span from the upper and lower surfaces of the bridge, which are pulled together under the deflection meters (USSR AS No. 1124184, IPC G 01 M 5/00).

However, this method is uninformative and is intended to measure deflections of bridge spans only when they are tested and does not allow an assessment of the current state of the bridge during its operation without the use of additional loads.

There is also a method for determining the deformation of structural elements, including creating a stress state in the element, attaching strain gauges to it, changing the stress state of the element and fixing the signals of the strain gauges. In this case, the load cells are fixed at points diametrically opposite relative to the axis of symmetry of the element, and the measurement of the stress state of the element is carried out by turning it 180 relative to the axis of symmetry (USSR AS No. 834429, IPC G 01 M 5/00).

However, in this method, deformations of structural elements are also determined under the influence of additional loads, and the measured parameter does not provide complete information about the state of the bridge as a whole.

Closest to the proposed one is a method for monitoring bridges, which, along with visual observations of defects in the bridge, also includes long-term observations of the deflections of the spans of the continuous part of the bridge based on the precision leveling of grades embedded in the curbstone according to a certain pattern. Leveling is carried out 2 times a year with the subsequent calculation of deflections according to the results of leveling. (Transport construction, No. 2, 1998, p.24-25).

However, in this method, a limited number of measured parameters does not allow obtaining information about the current state of the bridge as a whole.

The objective of the proposed method is to obtain comprehensive and reliable information about the current state of the bridge (structural elements) during its operation and, as a result, timely detection of both obvious and hidden defects. Based on the measurement results, recommendations are given for repair and maintenance work, which ultimately ensures increased durability and safe operation of the bridge. The application of this method is especially relevant with increasing life of the bridge.

The problem is solved in that in a method for monitoring a bridge crossing during its operation, including visual control with the identification of visible defects and instrumental control by periodically measuring parameters - deflections of the bridge spans before operation and during operation, comparing parameters, assessing the condition of the bridge The comparison results, according to the proposed solution, additionally measure the following parameters characterizing the general stress-strain state of the structure bridge: transverse and longitudinal displacements of spans relative to the supports, while longitudinal displacements are measured at the nodes of the support of the span under expansion joints, deviations of the support section, stresses in the support sections of the spans and the middle part of the spans, amplitude and frequency of the spans, draft supports for continuous spans and deviations of supports from the vertical axis at the top of the head, threshold values are calculated for all measured parameters, and the estimate ence bridge performed on the basis of comparison values each measured parameter before operation or during operation with the respective calculated thresholds, and the measurements are at least 2 times per year.

In addition, hydrometeorological observations are systematically carried out, including the collection of information on wind speed and direction, air temperature and humidity, mass of icy-hoarfrost deposits, snow depth, river depth, current velocity, ice conditions, and chemical composition of air in areas of heavy traffic.

The invention is illustrated by drawings, where Fig. 1 is a block diagram for implementing the method, Fig. 2 is a general view of a bridge, Fig. 3 is a cross section of a span, and Fig. 4 is a cross section of a support. 5 is a table of symbols.

The positions in the drawings indicate:

1 - span,

2 - support

3 - lower belt span,

4 - span box,

5 - the axis of the box span (axis of the support),

6 - road section of the superstructure,

7 - orthotropic plate of the roadway,

8 - head of the support.

The method is as follows.

During the construction of the bridge over the entire period of operation, constant supervision of the technical condition of the structure is established, including routine and periodical inspections, as well as special inspections, examinations, tests and instrumental observations.

Before the start of operation, the following information parameters are measured: the planned position of the span 1 — longitudinal and transverse profiles and the position of the supports 2, measure the deflection of the span under static loading with a test load, the amplitude and frequency of vibration of the span from dynamic load, and also the value of stresses in the cross sections spans (in the central part of the span and supporting sections) defined by the test program.

In the process of operation, to determine the operational suitability of the main load-bearing structures, information parameters are periodically monitored with the help of computers, and during their processing they are compared with threshold - calculated values, taking into account the initial parameters of the bridge structural elements measured before the start of operation. In particular, the following parameters are measured:

- the movement of spans (longitudinal and transverse);

- stress (deformation) in the supporting sections and the middle part of the spans;

- longitudinal (deflection and deviation) and transverse profiles of the span;

- precipitation of supports;

- spatial position of the intermediate supports;

- the amplitude and frequency of the span.

In this case, the last four parameters can be used to determine the causes of damage.

In addition, hydrometeorological data are accumulated to determine the effect of hydrometeorological impacts on the structure. Hydrometeorological observations include the collection of information on wind speed and direction, air temperature and humidity, mass of icy-hoarfrost deposits, snow depth, river depth, flow velocity, ice conditions, chemical composition of air in areas of heavy traffic, etc.

In addition, they carry out measurements related to the maintenance of the bridge channel, regulatory and shore protection structures.

To measure the above parameters, choose the following location of the measurement points.

The longitudinal displacements of the span are measured relative to the supports 2. The measurement points are located at the nodes of the hinged support of the span on the support parts in the level of the lower belts 3 and on the expansion joints in the level of the top of the carriageway.

Transverse movements of the span are determined by the deviation from the calculated axis along the roadway at least at three points.

Stresses (strains) of the spans of the transition are measured in the elements of the span characterizing the general stress state of the structure.

The vertical longitudinal profile of the transition is determined by the axes of 5 boxes 4 spans 1. This arrangement of measurement points also allows you to obtain information about the transverse profile of the road part with a given resolution.

The horizontal longitudinal profile (the position of the span of the transition in plan) is measured by the length of the span at the level of the orthotropic plate 7 of the carriageway 6.

Span vibrations are measured in the vertical and horizontal planes of the span. The measuring points are located in the middle of the spans, which allows you to register bending and torsional vibrations of the structure.

Precipitation of all intermediate transition supports is determined at the level of the top of the head 8.

The spatial position of all transition supports is determined by the body of the supports in two levels along two axes.

The measurement of the angle of inclination of all intermediate supports of the transition is determined at the level of the top of the head 8.

The temperature of the structure is measured in shaded places along the entire length of the transition.

Instrumental control when monitoring the bridge crossing is carried out using standard methods and commercially available measuring instruments. The entire measuring complex is integrated into a single information-measuring monitoring system, built on the basis of a computer.

It consists of primary converters (sensors) of controlled parameters, measured data storage devices, data collection and transmission tools, calculators with a wide range of input-output devices.

The geometric characteristics of the transition structure and the angular displacements of its elements are determined by geodetic methods. Stresses in the structural elements of the span are measured using portable comparators based on dial gauges and support elements forming the measurement base and electromechanical strain transducers. Oscillations of the span are recorded by seismic vibration measuring equipment. Horizontal (span and transverse) displacements of spans are measured relative to intermediate supports by electromechanical displacement transducers with remote analog registration in dynamic mode and with the help of optical or mechanical meters of linear dimensions during long-term observations. A monitoring system can be built on the basis of fully automated remote measurements of controlled information parameters, which are a combination of hardware and software.

The collection of information characterizing the parameters of the transition and the technical condition of the structure is carried out: by remote measurements, direct measurements and visual observations. The data obtained during remote measurements are stored on magnetic media and entered into the automated system through computer units with peripheral devices. Data obtained by direct measurements and visual observations are recorded in the observation logs and entered into the automated system from the computer keyboard.

Data collection during remote measurements is carried out using a computer installed in a mobile laboratory, and information storage and processing is carried out using a stationary computer.

An automated system consists of four functional blocks: an information collection unit, an information processing unit, a unit for presenting processing results, an analysis unit for results, and issuing recommendations. The information collection unit includes measurement data giving quantitative information, and observations giving qualitative information. The measurement results are classified depending on the physical method of obtaining data: electrical, mechanical and optical. Observations can be scheduled, periodic or unscheduled (if defects and damages are detected, after repairs, after exposure to the construction of extreme loads and natural factors, when information is obtained through measurements about invalid parameter values, and in other cases). Pre-processing of measurement results and obtaining (evaluation or identification) based on them data characterizing the parameters of the structure, is performed in the information processing unit. The unit for the presentation of measurement results allows you to obtain information about the state of the structure in tabular or graphical forms on paper. The unit for analyzing the results of measurements and observations is intended to compare data on the initial and current state of the structure with the calculated parameters of its operation, which allows us to assess the danger of a change in the time of the measured structural parameters for the bridge crossing. The user of the automated system receives at the block output quantitative assessments in the cumulative mode necessary for making decisions regarding the need for repair, preventive and other works at the construction.

The implementation of the method requires equipping the bridge with measuring points that are located directly on the bridge or adjacent sections, and include primary transducers (sensors), grades, benchmarks, measuring equipment and devices that directly measure the parameters of the structure located at the locations of the remote measurement points .

The measured parameters are compared with the calculated threshold values obtained on the basis of current regulatory documents.

Moreover, the excess of each parameter over the calculated threshold is not permissible.

EXAMPLE.

The monitoring method of the bridge crossing in the process was tested when observing the bridge crossing the Volga River near the village. Pristannoe of the Saratov region. The bridge is a structure with steel beam-continuous spans of constant height with a box-shaped cross section consisting of L-shaped elements. Measurement of information parameters was carried out for 1 year.

When determining the vertical longitudinal profile of spans, the vertical longitudinal and transverse profiles of the carriageway, the vertical settlement of the supports, the displacements were measured using a 2N-3L level and the MP 256 memory module, and the N-05 level was also used to measure the vertical settlement of the supports. To determine the spatial position of the supports, the displacements and the angle of inclination were measured using the 3T5KP theodolite and the electronic mode level. 128. The general deformations (deflections) of the spans under load were investigated using the PSKTV-3 6 PAO-LISI deflection meter. To measure relative displacements (strains), a K-420 mechanical portable comparator, a linear strain gauge transducer PLDS-400, and a digital portable periodometer PTsP-1 were used. A set of vibration equipment based on the C5C + BFH seismic receiver and the analogue of the SPAI-8/8 digital converter was used to determine the span vibrations (the amplitude, frequency, and attenuation decrement were measured) and the horizontal spans of the span when exposed to the structure by an automobile load. The planned position of the spans was determined by measuring displacements using the 3T5KP theodolite. Local deformations, the opening of expansion joints and the position of the supporting parts were determined using a metal ruler and a caliper.

Measurements of the vertical longitudinal and transverse profiles of the carriageway were carried out in the current mode along the entire length of the bridge at points above the supports and in the middle of each span and adjacent areas. The planned position of the span and the longitudinal profile of the span were determined at the same points with the exception of adjacent zones, while the last parameter was measured monthly. The spatial position of the supports and their draft were also measured periodically. General deformations (deflections of spans), deformations in structural elements and vibrations of spans were measured in randomly selected 2-3 spans in their middle part.

The information obtained as a result of the monitoring work is intended to assess the technical condition of the structure and establish the causes of damage in case of their occurrence. In addition, the results of the survey are the basis for solving special issues of the operation of the transition, including for the development of repair projects, structural reinforcement, and special load bridge passes.

In the proposed method, a system of long-term observations (monitoring) and supervision of the technical condition of the bridge is implemented, which is implemented using a single automated diagnostic program complex.

Claims (2)

1. A method for monitoring a bridge crossing during its operation, including visual control with the identification of visible defects and instrumental control by periodically measuring parameters - deflections of the bridge span before and during operation, comparing parameters, evaluating the state of the bridge according to the comparison results, characterized in that additionally measure the following parameters characterizing the overall stress-strain state of the bridge structures: transverse and longitudinal displacements flight structures relative to the supports, while longitudinal displacements are measured at the support points of the span under expansion joints, deviations of the support section, stresses in the support sections of the spans and the middle part of the spans, the amplitude and frequency of oscillations of the spans, the settlement of supports for continuous spans and deviation supports from the vertical axis at the level of the top of the head, threshold values are calculated for all measured parameters, and the state of the bridge is assessed by comparing of each measured parameter before the start of operation and during operation with the corresponding calculated threshold values, while the measurements are carried out at least 2 times a year. 2. The method according to claim 1, characterized in that hydrometeorological observations are additionally systematically carried out, including collecting information about wind speed and direction, air temperature and humidity, mass of icy-hoarfrost deposits, snow depth, river depth, flow velocity, ice conditions , chemical composition of air in areas of heavy traffic.

Images