A bridge existing bearing capacity evaluation method based on influence surface

Abstract

The application discloses a kind of bridge existing bearing capacity evaluation methods based on influence surface, comprising the following contents: inclination instrument is arranged in each monitoring point of the bridge surface to be measured;Distance measuring instrument is provided on loading vehicle, vehicle travels according to established route, and distance and inclination data are transmitted to control terminal by synchronous acquisition of distance measuring instrument and inclination instrument, control terminal calculates the displacement of each monitoring point, and vehicle position and bridge deflection information are displayed in real time;Position-deflection curve is determined by single vehicle driving measurement in each lane, and then the deflection influence line of each lane is calculated;Based on the deflection influence line of each lane, the deflection influence surface of the main girder of the bridge to be measured is synthesized;The load position and load value of the test condition to be measured are input into the deflection influence surface, and the deflection estimated value is obtained, which is compared with the allowable value of load specification, to evaluate the bearing capacity of the bridge.The deflection influence surface of the bridge is obtained by rapid load test, the existing bearing capacity of the bridge can be effectively judged, the test time is short, and the identification precision is high.

Description

TECHNICAL FIELD

[0001] The present application relates to a bridge bearing capacity evaluation method, in particular to a bridge existing bearing capacity evaluation method based on influence surface. BACKGROUND

[0002] For a long time, the bridge bearing capacity research has been the main research focus in the bridge engineering field. The research in this field is currently mainly divided into two aspects: one is the evaluation of the bearing capacity of existing bridges; and the other is the research on the ultimate bearing capacity of bridges. For the evaluation of the bearing capacity of existing bridges, the main concern is the prediction of the basic performance of the existing bridge structural system and the future safety, including the strength and stability of the bridge structure or component, the rigidity of the foundation and base, the structure or component, the cracking condition of the structure or component and the like; the main purpose of the research on the ultimate bearing capacity of bridges is to analyze the ultimate bearing capacity of the bridge structure, for the ultimate design, to understand the failure mode of the structure, to accurately grasp the structural safety reserve or overload capacity, so as to provide the basis and guarantee for the safe construction and operation management.

[0003] For many years, scholars at home and abroad have proposed many bridge evaluation methods in the research on the evaluation technology of the bearing capacity of existing bridges, which have played a significant role in the evaluation of the bearing capacity of existing bridges. At the same time, according to the actual situation of their own, various countries have proposed their own evaluation methods or criteria for old bridges, for guiding the evaluation of the bearing capacity of existing bridges.

[0004] At present, the commonly used methods for the evaluation of the bearing capacity of existing bridges at home and abroad mainly include the appearance investigation method, the analysis calculation method, the load test method, the reliability analysis method, the expert system method and the like. The comparison of the advantages and disadvantages of these commonly used bridge evaluation methods is shown in Table 1.

[0005] Table 1 Comparison of the advantages and disadvantages of various evaluation methods

[0006]

[0007]

[0008] It can be seen that the traditional bridge bearing capacity evaluation method has defects such as non-standard, strong subjectivity, large scale, high cost, long time and the like, and the new type of evaluation method is still in the theoretical research stage, and there are many limitations in practicality, which is difficult to popularize and apply. SUMMARY

[0009] The present application relates to a bridge bearing capacity evaluation method, in particular to a bridge existing bearing capacity evaluation method based on influence surface.

[0010] Technical scheme: A bridge existing bearing capacity evaluation method based on influence surface comprises the following contents:

[0011] (1) In each monitoring point of the bridge deck to be measured, an inclinometer is arranged, and the inclinometer is zeroed;

[0012] (2) A range finder is arranged on the loading vehicle, and the loading vehicle drives on the bridge according to the predetermined route, the range finder and the inclinometer synchronously collect distance and inclination data, and the data is transmitted to the control terminal in a wireless transmission mode, the control terminal calculates the vertical displacement values of each monitoring point, and the vehicle position and the bridge deflection information are displayed in real time;

[0013] (5) The position-deflection curve is determined by the driving measurement of the single vehicle in each lane, and then the deflection influence line of each lane is calculated;

[0014] (6) Based on the deflection influence line of each lane, the deflection influence surface of the main girder of the bridge to be measured is synthesized;

[0015] (7) The load position and load value of the test working condition are input into the deflection influence surface, the deflection estimation value is obtained, the deflection estimation value is compared with the allowable value of the load specification, and the bearing capacity of the bridge is evaluated.

[0016] Further, in step (2), the bridge deflection information is calculated by the following method:

[0017] The span of the i-th span of the bridge structure is defined as L i , and the span L i is equally divided into DF i parts, obtaining the first to DF i +1 part points, and the equally divided distance is h; wherein i∈[1,N], N is a positive integer;

[0018] The inclinometer is arranged at each part point, and the measured angle value of each part point is obtained by the inclinometer, and the vertical displacement value of each part point is calculated according to the measured angle value.

[0019] Specifically, the vertical displacement value of the third to DF i +1 part points of the i-th span is calculated by Simpson's integral formula, and the vertical displacement value of the second part point and the DF i +1 part point of the i-th span is calculated by trapezoidal method.

[0020] Preferably, the vertical displacement value of the DF i +1 part point of the i-th span is taken as the measurement point error accumulation value, the vertical displacement value of the j-th measurement point of the i-th span girder is corrected to obtain the corrected vertical displacement value WL(i,j).

[0021] Then, the DF i +1 part point is taken as the starting point, and Simpson's integral formula is used to obtain the vertical displacement value WR(i,j) of the j-th measurement point of the i-th span girder in the reverse direction.

[0022] The average value of WL(i,j) and WR(i,j) is the estimated deflection value of the jth measuring point of the i-th span beam:

[0023] W(i,j)=|WL(i,j)-WR(i,j)| / 2.

[0024] Furthermore, in step (2), the inclinometer data is corrected by a deflection correction algorithm.

[0025] Furthermore, in step (5), the position-deflection curve is corrected and the deflection influence line of each lane is calculated. Preferably, vertical and horizontal alignment correction algorithms are used to correct the deflection response anomaly of the position-deflection curve.

[0026] Furthermore, in step (6), the deflection influence surface is calculated by a spline interpolation algorithm.

[0027] Compared with the existing methods, the present invention has the following beneficial effects:

[0028] 1. The test of the present invention is quick, and vehicles of equal weight pass through the bridge at the same speed along a fixed track without interrupting traffic for a long time.

[0029] 2. The present invention eliminates abnormalities in the inclinometer data based on the inclinometer deflection measurement correction algorithm, and adopts the influence line test method based on a single lane to obtain the bridge deflection information. The test accuracy is high, and the actual bridge error is within 2%. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a flow chart of a bridge bearing capacity assessment method according to an embodiment of the present invention;

[0031] Figure 2 This is a schematic diagram of the arrangement of inclinometer measuring points for a domestic bridge in one embodiment of the present invention;

[0032] Figure 3 This is a transverse arrangement diagram of the load deflection measurement points of a domestic bridge (unit: m) (48m span) in one embodiment of the present invention;

[0033] Figure 4 This is a transverse arrangement diagram of the inner side eccentric load deflection measuring points of a domestic bridge (unit: m) (48m span) in one embodiment of the present invention;

[0034] Figure 5 The time history of the original inclination data of each measuring point in which the inclinometer has an abnormal drift trend in one embodiment of the present invention;

[0035] Figure 6 To eliminate Figure 5 The time history of the inclination data at each measuring point after the abnormal trend is shown;

[0036] Figure 7 The deflection time history curves of each measuring point of the large bridge body are obtained based on the traditional uncorrected inclinometer deflection measurement algorithm;

[0037] Figure 8 The deflection time history curves of each measuring point of the large bridge body obtained based on the deflection correction algorithm of one embodiment of the present invention;

[0038] Figure 9 This is the linear result of the inclinometer deflection measurement of the 7# hole beam under positive load test in one embodiment of the present invention;

[0039] Figure 10 This is the linear result of the inclinometer deflection measurement of the eccentric load condition test of the 7# hole beam in one embodiment of the present invention;

[0040] Figure 11 This is the deflection comparison of the 4# measuring point under the positive load condition of the static load test in one embodiment of the present invention;

[0041] Figure 12 The deflection comparison of the 4# measuring point in the static load test under the eccentric load condition in one embodiment of the present invention is shown;

[0042] Figure 13 The alignment of the main beam of span 7# under various static load test conditions;

[0043] Figure 14 The distance-deflection curve obtained by measuring the data of a loaded vehicle driving in each lane and corrected by vertical alignment;

[0044] Figure 15 The distance-deflection curve obtained by measuring the data of a loaded vehicle driving in each lane after being corrected for horizontal alignment;

[0045] Figure 16 The distance-deflection curve obtained by measuring the data of a loaded vehicle in each lane after vertical and horizontal alignment correction;

[0046] Figure 17 This is a comparison chart of mid-span deflection under single-vehicle and multi-vehicle parallel working conditions in quasi-static rapid load test;

[0047] Figure 18 It is the deflection influence surface at measuring point No. 4 in the middle of the span of the 7# main beam in one embodiment of the present invention. DETAILED DESCRIPTION

[0048] The technical solution of the present invention is explained and illustrated in detail below with reference to the accompanying drawings and specific embodiments.

[0049] like Figure 1 As shown, a flow chart of a bridge bearing capacity assessment method according to an embodiment of the present invention includes a data collection process and a bearing capacity assessment process.

[0050] Data acquisition process: the bridge deck is laid with an inclinometer, and the laid inclinometer is zeroed, then an equal weight and speed vehicle is used to pass through the bridge, and the inclinometer data is corrected, and based on the corrected data, Simpson integral method is used to calculate the deflection value of each monitoring point (i.e. the vertical displacement value of each monitoring point of the bridge), and then the bridge displacement influence line is obtained, and further the influence surface is formed.

[0051] Load capacity evaluation process: the expected load of the standard load test is input into the influence surface model to obtain the deflection estimate value, which is compared with the allowable value in the load specification to evaluate the existing bearing capacity of the bridge.

[0052] It should be noted that, Figure 1 The "deflection extreme value" mentioned in the background art is the deformation value (mm) corresponding to the lowest point of the structure vertical deformation time history curve based on the inclinometer measurement, which is used to generate the lane influence line (indicating the vertical deformation amount of the midspan monitoring point when a unit weight is applied at a certain position on the bridge deck, mm / t), which is not the same concept as the ultimate bearing capacity of the bridge in the background art, i.e. the technical solution of the present application is not applicable to the ultimate bearing capacity evaluation.

[0053] I. Inclinometer data acquisition and deflection calculation

[0054] Table 1 Bridge structure span information

[0055]

[0056]

[0057] Determine the bridge structure span information, define the span of the i-th span of the bridge structure as L i , divide the span L i into equal parts, the number of equal parts is DF i , and DF i +1 segment points are obtained, i.e. the span has DF i +1 monitoring points, and the equal division distance is h; wherein i∈[1,N], N is a positive integer;

[0058] Inclinometers are laid at each monitoring point, and the measured values of the angles of each segment point are obtained from the inclinometers, and the vertical displacement values of each segment point are calculated according to the measured values of the angles.

[0059] The algorithm flow of deflection calculation is as follows:

[0060] (1) Initialize the bridge structure span information;

[0061] S1.1 Read the span L and the equal division number DF of each span;

[0062] S1.2 Check whether the span L and the number of equal divisions DF meet the following requirements:

[0063] ①The span is a positive number;

[0064] ②The number of equal parts is an integer greater than 4;

[0065] (2) Read the rotation angle value ZJ(N, DF) at each span dividing point;

[0066] (3) Cycle each span;

[0067] S3.1 calculates the starting position of the current span;

[0068] S3.2 calculate the current position across each equally divided point;

[0069] S3.3 According to the equal division distance of each span and the measured value of the rotation angle of each quantile, the 3rd to DF of the current span are i +1 quantile using Simpson integral method to calculate the vertical displacement value WL(DF i +1);

[0070] S3.4 Use the trapezoidal method to calculate the vertical WL2 displacement value of the second quantile of the current span and the DF i Percentile vertical displacement value WL DFi :

[0071]

[0072]

[0073] S3.5 Calculate the current cross-DF based on the Simpson method i The vertical displacement value at the +1 quantile is calculated as WL(DF i +1); Due to the first measuring point and the DF i +1 measuring point is located at the beam section of the pier at the end of the span bridge beam, and the deflection or displacement of the main beam at the pier top should always be 0, that is, theoretically WL(DF i +1)=0, but due to the existence of measurement error, WL(DF i +1)≠0, therefore, this value is used as the cumulative value of the measuring point error, and the value of each measuring point is corrected;

[0074] The correction formula is as follows:

[0075]

[0076] Where WL(j) is the displacement value before correction, and WL'(j) is the displacement value after correction. WL(j) is replaced by WL'(j) to offset the influence of the measurement cumulative error.

[0077] The vertical displacement value WL(i,j) of the i-th span at the j-th measuring point is obtained, j = 2, 3, …, DF i +1;

[0078] S3.6 The i-th span is reversely Simpson integrated with the DF i +1 quantile points as the starting points, and the vertical displacement value WR(i,j) of each measuring point of the i-th span beam body in the reverse direction is obtained based on steps S3.3-S3.5;

[0079] S3.7 The WL(i,j) and WR(i,j) are averaged to obtain the final deflection estimation value of the i-th span beam body:

[0080] W(i,j) = |WL(i,j) - WR(i,j)| / 2;

[0081] It should be noted that the sign of WR(i,j) and WL(i,j) in the displacement calculation result of the same measuring point is opposite, and therefore the above formula is obtained by subtracting and then taking the absolute value of the average value;

[0082] S3.8 The deflection measurement line is drawn according to the quantile point position and the vertical displacement value of the current span.

[0083] II. Static load test

[0084] Test object: The 3-span main bridge of the south span of a domestic bridge, a three-span variable load surface continuous beam bridge, with a total length of 112m, a span combination of 35m+48m+29m = 112m, and a total bridge deck width of 32.0m. The mid-span box girder has a height of 1.6m, and the box girder at the pier has a height of 3.2m.

[0085] (1) Vehicle load

[0086] The static load test uses 6 vehicles with a total weight of about 36 tons for equivalent loading. The static load test process of the bridge is divided into two types of working conditions: positive load and eccentric load.

[0087] Table 2 Loading vehicle wheelbase and axle load table

[0088]

[0089]

[0090] Table 3 Static load test test conditions and test content

[0091]

[0092] (2) Inclination instrument measuring point arrangement

[0093] Inclinometer (tilt meter) layout: inclinometers are arranged on the south side of the 48m span non-motor vehicle lane in the south range, 7 measuring points are arranged at equal intervals, and the inclinometers on the top of 6# and 7# piers are taken as reference points; the cross-section layout position is shown in Figure 2 Table 4.

[0094] Table 4. Inclinometer measuring point number correspondence table

[0095] Measurement point number Sensor number Measurement point position 1 ND010101 6# pier top bridge deck south side 2 ND010102 1 / 6 span bridge deck south side from 6# pier 3 ND010103 1 / 3 span bridge deck south side from 6# pier 4 ND010104 7# hole midspan bridge deck south side 5 ND010105 2 / 3 span bridge deck south side from 6# pier 6 ND010106 5 / 6 span bridge deck south side from 6# pier 7 ND010107 7# pier top bridge deck south side

[0096] (3) Level measuring point arrangement

[0097] The deflection test process is synchronized with the static load test of the bridge to verify the effectiveness and stability of the deflection test method of the inclinometer girder. The static load test process of the bridge is divided into two types of working conditions, i.e. positive load and eccentric load. During the process, the deflection of the girder of hole 7 is measured by arranging measuring points on the bridge deck and using electronic level to measure the relative elevation, and the deflection of the girders of holes 6 and 8 is measured by arranging dial gauges on the beam bottom. The deflection measuring point arrangement is shown in Figure 3 、 Figure 4 .

[0098] III. Inclinometer abnormal data correction and effectiveness analysis

[0099] During the field detection process of the inclinometer, due to environmental noise, installation defects, electromagnetic interference and other reasons, the measurement stability is bound to be poor, and measurement errors are formed. The present application filters out abnormal jump point data in the inclinometer measurement data by using a noise point filtering algorithm; and based on a cross-correlation diagnostic algorithm, it detects whether the data has an abnormal drift trend, and uses a correlation maximization method to process the drift data to eliminate the abnormal trend.

[0100] As shown in Figure 5 、 Figure 6 , based on the cross-correlation diagnostic algorithm, it is judged that the time history of the sensor ND010105 incline angle data has a significant drift, and the correlation maximization method is used to eliminate the data trend to prevent the subsequent deflection calculation based on the incline angle data from having too large errors and seriously affecting the accuracy of the deflection estimation.

[0101] Based on the incline angle data of each measuring point under the static load test of the bridge, the deflection time history of each measuring point of the bridge girder is calculated by using the traditional uncorrected incline angle deflection measurement algorithm and the correction algorithm proposed in the present application respectively, the time history is compared, and the effectiveness of the correction algorithm is analyzed.

[0102] Figure 7 、 Figure 8The deflection time history curves of each measuring point of the bridge beam obtained based on the traditional uncorrected tiltmeter deflection measurement algorithm and the deflection correction algorithm of the present application respectively. As can be seen from the figure, in general, the deflection data obtained based on the tiltmeter deflection measurement algorithm can dynamically reflect the change trend of the beam deflection and can generally reflect the deflection deformation of each measuring point under different load test conditions.

[0103] Figure 7 For the deflection calculation results of each measuring point without deflection error correction intervention, it can be seen from the figure that without correction, as the measurement time continues, the deflection calculation results may appear divergence phenomenon, especially after the end of the 6 static load conditions, the deflection calculation values of each measuring point reflect different degrees of residual deformation, the residual deformation of the deflection at the midspan position reaches-3.54mm, and the relative residual deformation is more than 50%, which obviously does not match the actual condition, and using such data to evaluate the structural bearing capacity will lead to large error.

[0104] Figure 8 The deflection time history curves of each measuring point calculated by using the deflection error correction algorithm proposed by the present application. As can be seen, based on the correction algorithm, the deflection of each measuring point basically returns to zero value after static test, and during the holding period under each condition, the deflection time history curve basically tends to be horizontal, and the data is relatively stable, which can solve the problem of deflection error accumulation caused by using interval integral algorithm.

[0105] Taking the 7# hole beam positive load and eccentric load test under conditions 3 and 4 as an example, as shown in Figure 9 , Figure 10 , under midspan load, the linear shape calculated based on the traditional algorithm appears the problems of upward deflection and poor linear transition, which leads to large deflection value at the midspan position, and the linear shape of the beam calculated based on the correction algorithm is more reasonable than that of the traditional algorithm.

[0106] IV. Comparative analysis of static test results

[0107] By comparing the deflection values of 7# span midspan measuring point based on the tiltmeter measurement with the measured values based on the level gauge and dial gauge at the same time of measurement during static load test, the accuracy of the deflection correction algorithm based on the tiltmeter is verified.

[0108] Assuming that the 4# measuring point midspan transverse influence line of the 7# hole main beam under different conditions obeys a quadratic polynomial function relationship, the deflection at the 4# measuring point position can be estimated based on the level gauge and dial gauge test data. As shown in Tables 5-6, Figure 11-12 , under each condition, the deflection values of the 4# measuring point obtained based on the tiltmeter measurement correction algorithm and the deflection values obtained based on the level gauge and dial gauge measurement are highly consistent. The error is larger under condition 2, which is suspected to be caused by the measurement error of the dial gauge due to the strong wind on that day.

[0109] Table 5 Comparison of deflection of 4# measuring point of tiltmeter under positive load condition of static load test

[0110]

[0111] Table 6 Static load test bias load working condition inclination instrument 4# measuring point deflection comparison

[0112]

[0113] Figure 13 For the 7# span girder line shape under each static load test condition. As can be seen from the figure, the deflection measured by the inclination instrument under different conditions can effectively reflect the main line shape. Compared with the measurement means of the traditional load test using the cross-level instrument and the dial gauge, the line shape data provides more structural deformation information, which provides effective technical support for subsequent structure main girder damage identification and stiffness decay disease cause analysis of different beam ends.

[0114] Five. Quasi-static rapid load test

[0115] In order to verify the effectiveness of the bridge deflection detection of the present application, the vehicle range finder is attached to the rear wheel position of the vehicle, and the vehicle drives on the 7# span from west to east, and the inclination angle data of each measuring point is measured by the inclination instrument. The deflection information is converted by the deflection measurement correction algorithm of the inclination instrument. The specific load condition is shown in Table 7.

[0116] Table 7 Quasi-static rapid load test condition

[0117] Working condition number Load position Working condition description Vehicle speed 1 Overtaking lane, driving lane, non-motor vehicle lane Three vehicles side by side driving 7km / h 2 Lane 1 (overtaking lane) Single vehicle driving 7km / h 3 Lane 2 (driving lane) Single vehicle driving 7km / h 4 Lane 3 (non-motor vehicle lane) Single vehicle driving 7km / h

[0118] Test procedure:

[0119] (1) Fix the vehicle range finder to the rear wheel hub position of the vehicle;

[0120] (2) Through the wireless transmission module, set the ranging parameters based on the vehicle hub parameters, and calibrate the range finder;

[0121] (3) The vehicle drives to the position of the measured bridge pier top, and the range finder is zeroed;

[0122] (4) The vehicle drives on the bridge at a speed less than 7km / h according to the predetermined route, and the range finder and the inclination instrument synchronously collect the distance and inclination angle data, and transmit them to the control terminal in a wireless transmission mode. The terminal displays the vehicle position in real time, and displays the bridge deflection information in real time through the deflection test correction algorithm of the inclination instrument;

[0123] (5) Obtain the position-deflection curve of the bridge after the vehicle drives in each lane, and then calculate the deflection influence line of each lane (i.e. the relationship line of position and unit time deflection);

[0124] (6) Based on the deflection influence line of each lane, synthesize the deflection influence surface of the measured bridge main girder;

[0125] (7) Based on the load position and load value of the working condition to be tested, the load is applied to the corresponding position of the deflection response surface, the deflection values ​​of the loads at different positions are calculated and summed, and finally the deflection value of the beam under the load condition to be tested is obtained.

[0126] In step (5), the deflection influence line of each lane should be corrected and then the deflection influence line of each lane should be calculated. Figure 14 、 Figure 15 The following are distance-deflection curves obtained by measuring the data of a loaded vehicle in each lane after vertical and horizontal alignment correction. Since loaded vehicles cannot travel at a completely uniform speed, the horizontal and vertical deflection responses of the structure at the ends of the bridge span may not conform to the actual working conditions. After correcting the abnormal deflection response, the deflection influence lines of each lane are finally obtained as shown below. Figure 16 shown.

[0127] like Figure 17 As shown in the figure, by comparing the maximum deflection response in the mid-span under three-lane driving, it can be seen that the sum of the deflection responses of a single lane is 2.33 mm, and the deflection response under multi-vehicle parallel working conditions is 2.46 mm, with a difference of 5.5%. This shows that the influence line test method based on a single lane has a high measurement accuracy guarantee.

[0128] Based on the calculation results of the single lane influence line, the deflection influence surface at the No. 4 measuring point in the middle of the test bridge span is further calculated using the spline interpolation algorithm, as shown in the figure: Figure 18 To verify the accuracy and effectiveness of the deflection influence surface, the loads from static load tests 3 and 4 were input into the influence surface, and the measured values ​​were compared with the calculated influence surface values, as shown in Table 8. It can be seen that the relative error between the calculated results based on the influence surface and the measured values ​​is within 2%, indicating that the quasi-static rapid load test method proposed in this invention can basically meet the accuracy and stability requirements of bridge static load testing.

[0129] The above embodiments are intended only to illustrate the technical concepts and features of the present invention. Their purpose is to enable those skilled in the art to understand the contents of the present invention and implement them accordingly. They are not intended to limit the scope of protection of the present invention. Those skilled in the art may make various improvements and modifications without departing from the principles of the present invention, and such improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A bridge existing bearing capacity evaluation method based on influence surface, characterized in that, The method comprises the following steps: (1) arranging an inclinometer at each monitoring point of the bridge deck to be measured, and zeroing the inclinometer; (2) arranging a distance measuring instrument on a loading vehicle, and driving the loading vehicle on the bridge according to a predetermined route, synchronously collecting distance and inclination data by the distance measuring instrument and the inclinometer, and transmitting the data to a control terminal in a wireless transmission mode, calculating vertical displacement values of the monitoring points by the control terminal, and displaying vehicle positions and bridge deflection information in real time; The bridge deflection information is calculated by the following method: The span of the i-th span of the bridge structure is defined as L i , the span L i is equally divided into DF i parts, and the first to DF i +1 parts are obtained, and the equally divided distance is h; wherein i∈[1,N], N is a positive integer; 3~DF of the ith span i The vertical displacement value is calculated by Simpson integral formula The vertical displacement value is calculated by trapezoidal method for the 2nd and the DFth quantile points of the ith span. i The vertical displacement value is calculated by trapezoidal method for the 2nd and the DFth quantile points of the ith span. The inclinometer is arranged at each sub-position, and the measured values of the rotation angles of the sub-positions are obtained by the inclinometer, and the vertical displacement values of the sub-positions are calculated according to the measured values of the rotation angles; Calculate the DF of the i-th span based on Simpson's method i The vertical displacement value at the +1 quantile is calculated as WL(DF i +1), and use the vertical displacement value as the cumulative value of the measuring point error to correct the vertical displacement value of the j-th measuring point of the i-th span beam; the correction formula is as follows: Wherein, WL(j) is the displacement value before correction, WL'(j) is the displacement value after correction, WL'(j) is used to replace WL(j), so as to offset the influence of the measurement cumulative error; The vertical displacement value WL(i, j) of the i-th modified cross-section at the j-th measuring point is obtained, j = 2, 3, …, DF i +1; DF i The Simpson integral formula is used to obtain the vertical displacement value WR(i,j) of the jth measuring point of the ith beam body in the reverse direction, with the DF+1 quantile point as the starting point. The average value of WL(i,j) and WR(i,j) is used as the final deflection estimation value of the i-th span beam body and the j-th measuring point: W(i,j) = |WL(i,j)-WR(i,j)| / 2; (5) determining a position-deflection curve by measuring the single vehicle driving in each lane, and then calculating the deflection influence line of each lane; (6) synthesizing the deflection influence surface of the main beam of the bridge to be measured based on the deflection influence line of each lane; (7) inputting the load position and load value of the test working condition into the deflection influence surface to obtain the deflection estimation value, comparing the deflection estimation value with the allowable value of the load specification, and evaluating the bearing capacity of the bridge.

2. The method of assessing the load carrying capacity of an existing bridge according to claim 1, wherein, In step (2), the inclinometer data is corrected by a deflection correction algorithm.

3. The method of claim 1, wherein, In step (5), the position-deflection curve is corrected, and then the deflection influence line of each lane is calculated.

4. The method of assessing the load carrying capacity of an existing bridge according to claim 3, wherein, In step (5), the vertical and horizontal alignment correction algorithm is used to correct the deflection response anomaly of the position-deflection curve.

5. The method of claim 1, wherein, In step (6), the deflection influence surface is calculated by a spline interpolation algorithm.

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