CN111487002A - Force measuring method for bridge spherical support - Google Patents

Abstract

The invention provides a force measuring method of a spherical bridge support, which is used for measuring the vertical load and the vertical displacement of the spherical bridge support and comprises the following steps: installing a first strain sensor on the upper support plate or the lower support plate, and acquiring the circumferential strain of the upper support plate or the lower support plate measured by the first strain sensor; calculating the vertical load of the upper support plate or the lower support plate according to the measured annular strain; and calculating the vertical displacement of the upper support plate or the lower support plate according to the calculated vertical load. According to the force measuring method for the spherical bridge support, the first strain sensor is arranged on the upper support plate or the lower support plate, the circumferential strain measured by the first strain sensor is utilized to calculate the vertical load and the vertical displacement of the upper support plate or the lower support plate, so that the problem of the spherical bridge support can be found at any time, the information of a bridge can be obtained in time, and a data base is provided for the replacement and maintenance of the spherical bridge support.

Description

Method for measuring force of spherical bearing of bridge

technical field

The invention belongs to the technical field of bridge structure or construction, and more particularly relates to a method for measuring the force of a spherical bearing of a bridge.

Background technique

The bridge bearing is an important part that connects the upper structure (beam body) and the lower structure (pier) of the bridge. It not only transmits the force and deformation of the superstructure to the substructure faithfully, but also adapts to the corners and displacements of the superstructure under the action of load, temperature, concrete shrinkage and creep, so that the superstructure can deform freely without generating additional Additional internal force. Therefore, the performance of the bearing is directly related to whether the entire bridge can work normally and its service life.

With the change of bridge traffic load and environmental conditions, the bearing force fluctuates greatly, and the long-term bias can also lead to insufficient, uneven or even voiding of the bearing force. It is accompanied by changes in the internal force of the main beam, the internal force of the beam, and the reaction force of the bearing, which changes the stress mode of the bridge structure, damages the main beam, the bridge deck and the pier, and reduces the service life of the bearing. Many diseases of the bridge bearing will lead to the loss of some or all functions of the bearing. If the inspection is not timely and the work with "disease", it will bring very serious harm to the bridge. At the same time, the bearing itself is a component in the bridge structure that is easily damaged but not easy to repair. After damage, it usually needs to be replaced. The replacement construction will affect or interrupt the traffic, easily causing economic losses and adverse social impacts.

At present, the measurement parameters such as force and displacement of the bridge bearing at home and abroad are mainly divided into three methods: one is the uniformly distributed integral force measuring bearing, which obtains the overall stress of the bridge bearing through various principles, but this kind of method It can only effectively measure the overall pressure load of the bearing, and cannot reflect the internal force distribution of the bearing in detail; the second is the non-uniform overall force measuring bearing, which obtains the overall force of the bearing by setting up discrete sensors. By introducing pressure sensors, telescopic variable resistors, fiber grating sensors, strain gauges and other sensitive elements into the traditional supports, the support can obtain the overall pressure of the support in the form of non-uniform force on the support. It reflects the internal force distribution of the bearing, and at the same time, the introduction of sensitive components also has a great impact on the bearing structure; the third is the bridge bearing voiding test method, but the current method has the characteristics of single test physical quantity and single measurement position. The overall measurement of the structure will greatly affect the mechanical properties of the support and other issues. Therefore, the existing support monitoring method cannot reflect the distributed force of the support, nor can it realize the effective integration of the sensitive element and the support.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a method for measuring the force of a bridge spherical bearing, which aims to solve the technical problems in the prior art that the distributed force of the bearing cannot be reflected and the effective integration of the sensitive element and the bearing cannot be realized.

In order to achieve the above-mentioned purpose, the technical scheme adopted in the present invention is to provide a force measuring method of a bridge spherical bearing for measuring the vertical load and vertical displacement of the bridge spherical bearing, comprising the following steps:

Install a first strain sensor on the upper support plate or the lower support plate, and obtain the hoop strain of the upper support plate or the lower support plate measured by the first strain sensor;

Calculate the vertical load of the upper support plate or the lower support plate according to the measured hoop strain;

The vertical displacement of the upper support plate or the lower support plate is calculated according to the calculated vertical load.

As another embodiment of the present invention, installing a first strain sensor on the outer peripheral wall of the upper support plate or the outer peripheral wall of the lower support plate includes: installing the first strain sensor on the outer peripheral wall of the upper support plate or the lower support plate An annular groove recessed radially inward is arranged on the outer peripheral wall of the support plate, a first strain sensor is installed in the annular groove, and the upper support plate or the lower support measured by the first strain sensor is obtained The hoop strain of the seat plate at the annular groove.

As another embodiment of the present invention, calculating the vertical load of the upper support plate or the lower support plate according to the measured hoop strain, including;

Calculate the vertical direction of the upper support plate or the lower support plate according to the hoop strain of the upper support plate or the lower support plate at the annular groove measured by the first strain sensor load.

As another embodiment of the present invention, the hoop strain of the upper support plate or the lower support plate at the annular groove is ε _x , wherein:

In the formula, εx _is the vertical stress of the upper support plate or the lower support plate at the ring groove, F is the vertical load of the upper support plate or the lower support plate, υ is Poisson’s ratio, E is the elastic modulus of the upper support plate or the lower support plate, A is the cross-sectional area of the upper support plate or the lower support plate at the ring groove;

According to the measured hoop strain of the upper support plate or the lower support plate at the annular groove, the vertical load F of the upper support plate or the lower support plate is calculated as,

As another embodiment of the present invention, the vertical displacement of the upper support plate or the lower support plate is ΔL, wherein:

In the formula, L is the axial height of the upper support plate or the lower support plate.

As another embodiment of the present invention, the installation of a first strain sensor on the outer peripheral wall of the upper support plate or the outer peripheral wall of the lower support plate further includes: installing a second strain sensor in the annular groove , obtain the hoop strain of the upper support plate or the lower support plate at the annular groove measured by the second strain sensor.

As another embodiment of the present invention, a plurality of the first strain sensors and a plurality of the second strain sensors are installed in the annular groove at equal intervals along the circumferential direction; the first strain sensors and the second strain sensors The strain sensors correspond one by one.

As another embodiment of the present invention, the bottom wall of the annular groove is arranged in parallel with the outer peripheral wall of the upper support plate or the outer peripheral wall of the lower support plate, and the side wall of the annular groove is parallel to the outer peripheral wall of the upper support plate or the lower support plate. The bottom wall of the ring groove is arranged vertically.

As another embodiment of the present invention, a rounded transition is adopted between the bottom wall of the annular groove and the side wall of the annular groove.

The beneficial effect of the force measuring method of the bridge spherical bearing provided by the present invention is: compared with the prior art, the force measuring method of the bridge spherical bearing of the present invention does not change the structure of the bridge spherical bearing on the premise of , install the first strain sensor on the upper support plate or the lower support plate, and use the hoop strain measured by the first strain sensor to calculate the vertical load and vertical displacement of the upper support plate or the lower support plate, so as to find out at any time For the problem of bridge spherical bearings, the information of the bridge can be obtained in time; it can not only assess the safety of construction, but also predict the safety of bridge use; at the same time, it can also provide a data basis for the replacement and maintenance of bridge spherical bearings, reducing economic losses and defects. social influence.

Description of drawings

FIG. 1 is a schematic structural diagram 1 of a bridge spherical bearing provided by an embodiment of the present invention;

2 is a second structural schematic diagram of a bridge spherical bearing provided by an embodiment of the present invention;

FIG. 3 is a schematic structural diagram of a bridge spherical bearing at an annular groove provided by an embodiment of the present invention.

In the figure: 1. Upper bearing plate; 2. Lower bearing plate; 3. First strain sensor; 4. Spherical crown lining plate; 5. Ring groove; 6. Second strain sensor.

Detailed ways

In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, but not to limit the present invention.

The force measuring method of the bridge spherical bearing provided by the present invention will now be described. The method for measuring the force of the spherical bearing of the bridge, which is used to measure the vertical load and the vertical displacement of the spherical bearing of the bridge, includes the following steps:

Install the first strain sensor 3 on the upper support plate 1 or the lower support plate 2, and obtain the hoop strain of the upper support plate 1 or the lower support plate 2 measured by the first strain sensor 3;

Calculate the vertical load of the upper support plate 1 or the lower support plate 2 according to the measured hoop strain;

Calculate the vertical displacement of the upper support plate 1 or the lower support plate 2 according to the calculated vertical load.

The bridge spherical bearing in this embodiment is a common spherical bearing structure in the prior art, including an upper bearing plate 1 , a lower bearing plate 2 , and a seat between the upper bearing plate 1 and the lower bearing plate 2 between the spherical crown liner 4. The upper end surface of the spherical crown lining plate 4 and the lower end surface of the upper bearing plate 1 are both planes, and the spherical crown lining plate 4 and the upper bearing plate 1 are in plane contact. The lower end surface of the spherical crown lining plate 4 is a downward convex spherical surface, the upper end surface of the lower bearing plate 2 is an upward concave spherical surface, and the spherical crown lining plate 4 and the lower bearing plate 2 are in spherical contact, as shown in FIG. 1 or FIG. 2 .

Compared with the prior art, the method for measuring the force of the bridge spherical bearing provided by the present invention, on the premise of not changing the structure of the bridge spherical bearing, installs the first A strain sensor 3, which uses the hoop strain measured by the first strain sensor 3 to calculate the vertical load and vertical displacement of the upper bearing plate 1 or the lower bearing plate 2, so as to find the problem of the bridge spherical bearing at any time and know it in time Bridge information; it can not only evaluate the safety of construction, but also predict the safety of bridge use; it also provides a data basis for the replacement and maintenance of bridge spherical bearings, reducing economic losses and adverse social impacts.

It should be noted that, regardless of whether the first strain sensor 3 is installed on the upper support plate 1 or the lower support plate 2, the vertical loads of the upper support plate 1 and the lower support plate 2 can be calculated. If the vertical load borne by the upper support plate 1 is F _up , through force transmission, the vertical bearing capacity transmitted to the lower support plate 2 is F _down = αF _up .

In addition, the first strain sensor 3 in this embodiment may use a grating sensor, and the grating sensor is mounted on the upper support board 1 or the lower support board 2 using a grating packaging process such as glue sealing or metallization packaging. The first strain sensor 3 is connected to the data acquisition device, and the data acquisition device directly reads the measurement data of the first strain sensor 3, and can directly calculate and display the vertical load and vertical displacement of the upper support plate 1 and the lower support plate 2 .

Please refer to FIG. 1 or FIG. 2 , as a specific embodiment of the method for measuring the force of the bridge spherical bearing provided by the present invention, a first A strain sensor 3, comprising: an annular groove 5 recessed radially inward is arranged on the outer peripheral wall of the upper support plate 1 or the outer peripheral wall of the lower support plate 2, and a first strain sensor 3 is installed in the annular groove 5, Obtain the hoop strain of the upper support plate 1 or the lower support plate 2 at the annular groove 5 measured by the first strain sensor 3 .

The vertical load of the upper support plate 1 or the lower support plate 2 is calculated according to the hoop strain of the upper support plate 1 or the lower support plate 2 at the annular groove 5 measured by the first strain sensor 3 .

Wherein, the hoop strain of the upper support plate 1 or the lower support plate 2 at the ring groove 5 is ε _x , where:

In the formula, εx _is the vertical stress of the upper support plate 1 or the lower support plate 2 at the ring groove 5, F is the vertical load of the upper support plate 1 or the lower support plate 2, and υ is the Poisson’s ratio , E is the elastic modulus of the upper support plate 1 or the lower support plate 2 , A is the cross-sectional area of the upper support plate 1 or the lower support plate 2 at the ring groove 5 .

According to the measured hoop strain of the upper support plate 1 or the lower support plate 2 at the ring groove 5, the vertical load F of the upper support plate 1 or the lower support plate 2 is calculated as,

According to the calculated vertical load F of the upper support plate 1 or the lower support plate 2, calculate the vertical displacement ΔL of the upper support plate 1 or the lower support plate 2,

In the formula, L is the axial height of the upper support plate 1 or the lower support plate 2 .

In order to achieve the purpose of not changing the spherical bearing structure of the bridge and measuring the circumferential strain of the first strain sensor 3, the first strain sensor 3 needs to be installed on the outer peripheral wall of the upper bearing plate 1 or the outer peripheral wall of the lower bearing plate 2 . Since the upper support plate 1 and the lower support plate 2 are rotary structures symmetrical along the central axis, when subjected to a vertical load, the measurement data of the hoop strain is very small, and the measurement accuracy of the first strain sensor 3 is low. In the case of inaccurate measurement data, if the measurement data of hoop strain is inaccurate, the calculated data of vertical load and vertical displacement will also be inaccurate.

However, in this embodiment, a ring groove 5 is provided on the upper support plate 1 or the lower support plate 2, and the upper support plate 1 or the lower support plate 2 will generate stress concentration at the ring groove 5, so the ring groove 5 The measured hoop strain is larger than the hoop strain measured at other parts of the upper support plate 1 or the lower support plate 2, that is to say, the hoop strain at the ring groove 5 is relative to the upper support plate 1 or the lower support plate. The hoop strain at other locations of the seat plate 2 is amplified.

The measured hoop strain at the annular groove 5 is amplified, so that the measurement accuracy becomes higher, and the vertical load and vertical displacement of the upper support plate 1 or the lower support plate 2 can also be accurately calculated.

In this embodiment, the bottom wall of the ring groove 5 is arranged in parallel with the outer peripheral wall of the upper support plate 1 or the outer peripheral wall of the lower support plate 2 . The side wall of the ring groove 5 is perpendicular to the bottom wall of the ring groove 5 , as shown in FIG. 1 .

Preferably, in order to avoid premature damage at the connection between the bottom wall of the ring groove 5 and the side wall of the ring groove 5, a rounded transition is used between the bottom wall of the ring groove 5 and the side wall of the ring groove 5, as shown in FIG. 2 .

The principle that the hoop strain at the annular groove 5 is amplified relative to the hoop strain at other positions of the upper support plate 1 or the lower support plate 2 will be described below.

First of all, in order to achieve the purpose of not changing the spherical bearing structure of the bridge and measuring the circumferential strain of the first strain sensor 3, the first strain sensor 3 is installed on the outer peripheral wall of the upper bearing plate 1 or the outer peripheral wall of the lower bearing plate 2 superior.

3 is a schematic structural diagram of the bridge spherical bearing provided at the ring groove 5 according to the embodiment of the present invention, the hoop strain at the outer peripheral wall of the upper bearing plate 1 or the outer peripheral wall of the lower bearing plate 2 is ε ₁ , in:

In the formula, F is the vertical load of the upper support plate 1 or the lower support plate 2, υ is the Poisson’s ratio, E is the elastic modulus of the upper support plate 1 or the lower support plate 2, and d ₁ is the upper support plate Diameter of seat plate 1 or lower seat plate 2.

The hoop strain of the upper support plate 1 or the lower support plate 2 at the ring groove 5 is ε ₂ , where:

In the formula, d ₂ is the diameter of the upper support plate 1 or the lower support plate 2 at the ring groove 5 .

From this, the signal amplification factor k can be obtained

The upper bearing plate 1, the spherical crown lining plate 4 and the lower bearing plate 2 can be made of materials such as Q345B, Q345C or ZG270-500.

The effect of magnified hoop strain on improving measurement accuracy is explained below through experiments:

A first strain sensor 3 is respectively installed on the outer peripheral wall of the lower support plate 2 and at the ring groove 5, the outer diameter d1 of the lower support plate ₂ is 480mm, and the outer diameter d2 of the lower support plate ₂ at the ring groove 5 According to the combined deformation of compression bending and compressive stress strength check, it can be taken as 267mm, and the _rated vertical load F _is applied to the upper support plate 1. F _{lower rating} = αF _{upper rating} .

If the vertical bearing capacity F _{is rated} at 5000kN, the Poisson’s ratio of Q345B steel is 0.25～0.3, take 0.3 for calculation, E=210GPa, the hoop strain ε1 of the outer peripheral wall of the lower support plate ₂ is:

The first strain sensor for measuring hoop strain, such as a fiber grating sensor, can usually measure about 10 micro-strains with an accuracy, while the hoop strain caused by the above-mentioned vertical bearing force under full load is only about 40 micro-strains. Therefore, the hoop strain caused by the vertical bearing capacity of the spherical bearing in practical application is difficult to be detected by the fiber grating sensor.

The hoop strain ε ₂ of the lower support plate 2 at the ring groove 5 is:

实现了测量灵敏度的提高。The hoop strain obtained at this time is much higher than the measurement accuracy of the fiber grating sensor, and the amplification factor of the measurement signal is

Improved measurement sensitivity is achieved.

Please refer to FIG. 1 or FIG. 2 , as a specific embodiment of the method for measuring the force of the bridge spherical bearing provided by the present invention, a first A strain sensor 3 further includes: installing a second strain sensor 6 in the annular groove 5 to obtain the circumferential strain of the upper support plate 1 or the lower support plate 2 at the annular groove 5 measured by the second strain sensor 6 .

Specifically, a plurality of first strain sensors 3 and a plurality of second strain sensors 6 are installed in the annular groove 5 at equal intervals along the circumferential direction; the first strain sensors 3 and the second strain sensors 6 are in one-to-one correspondence. The first strain sensor 3 is arranged laterally, and the second strain sensor 6 is arranged vertically.

The above descriptions are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention shall be included in the protection of the present invention. within the range.

Claims (9)

1. The force measuring method of the spherical bridge support is used for measuring the vertical load and the vertical displacement of the spherical bridge support, and is characterized by comprising the following steps of:

installing a first strain sensor on an upper support plate or a lower support plate, and acquiring the circumferential strain of the upper support plate or the lower support plate measured by the first strain sensor;

calculating the vertical load of the upper support plate or the lower support plate according to the measured annular strain;

calculating a vertical displacement of the upper seat plate or the lower seat plate according to the calculated vertical load.

2. The method of claim 1, wherein mounting a first strain sensor on the upper or lower support plate comprises: the circumferential wall of upper bracket board or set up along radial inside sunken annular on the circumferential wall of lower carriage board install first strain sensor in the annular, acquire first strain sensor measurement upper bracket board or lower carriage board in the hoop strain of annular department.

3. The method of claim 2, wherein calculating the vertical load of the upper or lower seat plate based on the measured hoop strain comprises:

and calculating the vertical load of the upper support plate or the lower support plate according to the annular strain of the upper support plate or the lower support plate at the ring groove, which is measured by the first strain sensor.

4. The method of claim 3, wherein the hoop strain of the upper support plate or the lower support plate at the ring groove is changed to a hoop strain_xWherein:

in the formula (I), the compound is shown in the specification,_xthe vertical stress of the upper support plate or the lower support plate at the annular groove is defined, F is the vertical load of the upper support plate or the lower support plate, upsilon is Poisson's ratio, E is the elastic modulus of the upper support plate or the lower support plate, and A is the cross-sectional area of the upper support plate or the lower support plate at the annular groove;

calculating the vertical load F of the upper support plate or the lower support plate according to the measured circumferential strain of the upper support plate or the lower support plate at the ring groove,

5. the method of claim 4, wherein the vertical displacement of the upper or lower seat plate is Δ L, wherein:

wherein L is an axial height of the upper or lower seat plate.

6. The method of claim 2, wherein the first strain sensor is mounted on the outer circumferential wall of the upper support plate or the outer circumferential wall of the lower support plate, and further comprising: and a second strain sensor is arranged in the ring groove, and the annular strain of the upper support plate or the lower support plate at the ring groove, which is measured by the second strain sensor, is obtained.

7. The method of claim 6, wherein a plurality of said first strain sensors and a plurality of said second strain sensors are mounted in said ring groove at circumferentially equal intervals; the first strain sensors correspond to the second strain sensors one to one.

8. The method for measuring the force of a bridge ball-type socket according to claim 2, wherein the bottom wall of the ring groove is disposed in parallel with the outer peripheral wall of the upper socket plate or the outer peripheral wall of the lower socket plate, and the side wall of the ring groove is disposed perpendicular to the bottom wall of the ring groove.

9. The method of claim 8, wherein a rounded transition is provided between the bottom wall of the ring groove and the sidewall of the ring groove.

Images