CN116593322B - Method for monitoring and evaluating service performance of key tooth glue joint of segmental spliced box girder - Google Patents

Method for monitoring and evaluating service performance of key tooth glue joint of segmental spliced box girder

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Publication number
CN116593322B
CN116593322B CN202310829454.9A CN202310829454A CN116593322B CN 116593322 B CN116593322 B CN 116593322B CN 202310829454 A CN202310829454 A CN 202310829454A CN 116593322 B CN116593322 B CN 116593322B
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joint
shear
stress
measuring points
key
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CN116593322A (en
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李彦兵
李鹏飞
李毅
董振华
邹威
魏思聪
蔡卫明
毛燕
韩旭
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Bay Area Super Major Bridge Maintenance Technology Center Of Guangdong Highway Construction Co ltd
Research Institute of Highway Ministry of Transport
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Bay Area Super Major Bridge Maintenance Technology Center Of Guangdong Highway Construction Co ltd
Research Institute of Highway Ministry of Transport
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N3/24—Investigating strength properties of solid materials by application of mechanical stress by applying steady shearing forces
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N19/00—Investigating materials by mechanical methods
    • G01N19/02—Measuring coefficient of friction between materials
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N3/02—Details
    • G01N3/06—Special adaptations of indicating or recording means
    • G01N3/068—Special adaptations of indicating or recording means with optical indicating or recording means
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/0001—Type of application of the stress
    • G01N2203/0003—Steady
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/0014—Type of force applied
    • G01N2203/0025—Shearing
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T90/00—Enabling technologies or technologies with a potential or indirect contribution to GHG emissions mitigation

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  • Analytical Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Automation & Control Theory (AREA)
  • Engineering & Computer Science (AREA)
  • Testing Of Devices, Machine Parts, Or Other Structures Thereof (AREA)

Abstract

The invention discloses a method for monitoring and evaluating the service performance of a joint bonding seam of a segmental assembled box girder, which comprises the steps of respectively arranging a plurality of first stress measuring points, a plurality of second stress measuring points, a plurality of third stress measuring points and vertical displacement measuring points of adjacent segments at the seam position of a suspected defect obtained by cracking defect or nondestructive testing in a 1/4-1/8 span length area of the girder, enabling the stress measuring points to be distributed in a tension zone and a compression zone of the seam section, arranging the plurality of first measuring points along the girder high-span seam, arranging the plurality of second measuring points on the key teeth along the girder high-direction, arranging the plurality of third measuring points on the key teeth on two sides of the seam along the girder high-direction at the same time, staggering the arrangement positions of the plurality of second measuring points, and evaluating the service state of the seam based on the monitoring results and the shearing-friction theory of the measuring points. The invention can solve the problems of poor feasibility, nondestructive testing result accuracy, lack of verification, load test result application limitation and the like of the current joint service condition lossy testing method.

Description

Method for monitoring and evaluating service performance of key tooth glue joint of segmental spliced box girder
Technical Field
The invention relates to the technical field of bridge keykang monitoring. More particularly, the invention relates to a method for monitoring and evaluating the service performance of a key tooth glue joint of a segment-assembled box girder.
Background
The girder body of the segmental prefabrication assembled bridge is divided into a plurality of segments along the longitudinal bridge direction, the segments are transported to the bridge position after the girder field pouring maintenance is finished, the hoisting segments are transported through mechanical equipment, prestress, joint gluing and the like are applied after installation and positioning, so that a plurality of segmental girders are integrated, and the girder has the advantages of high construction speed, small influence on surrounding traffic, flexible construction, large span adaptation range and the like, and can be widely popularized and applied in the construction of the current prestressed concrete girder bridge. However, the segmental prefabrication assembled bridge has a large number of segmental splicing joints, reinforcing steel bars at the joints are interrupted, joint glue has a humid heat aging phenomenon, mechanical properties of joint sections are degraded and cracked under the action of complex bending and shearing stress in the service process, the overall performance of the segmental assembled bridge is seriously influenced, and even the service performance of local and overall structures of the bridge is influenced. Therefore, by developing the monitoring of the relevant service performance indexes of the joint seams of the segment spliced girder, the change characteristics and the evolution rules of the service states of the joint seams of the segment spliced girder are mastered, and basic data can be provided for further developing the evaluation of the service performance of the segment spliced girder bridge.
The service condition of the current segment spliced girder bridge is mainly obtained by coring damage detection and nondestructive ultrasonic detection methods, such as cracking, interfacial peeling and the like. In the nondestructive ultrasonic detection method, under the influence of internal reinforcing steel bars or service bridge reinforcing measures, distribution positions of test lines and test areas and the like, the precision and accuracy of the detection result of the segment joint service state are greatly influenced, the detection result cannot be well verified, and the judgment of suspected defect conditions lacks certain performance index verification. The service state and performance characterization index of the segment spliced seam are the main content of performance evaluation of the segment spliced bridge structure, so a real bridge load test method is also adopted at present, the connection performance of the segment spliced seam is evaluated by measuring the vertical displacement difference and the segment strain change of adjacent segments under the action of vehicle load, and the applied vehicle load is smaller and is different from the load condition in the operation process, so that the segment displacement change is smaller, and the defect and the performance condition of the segment spliced seam are not easy to distinguish.
Disclosure of Invention
The invention aims to provide a method for monitoring and evaluating the service performance of a key tooth joint of a segment spliced box girder, which overcomes the defects of the current joint service performance evaluation result inaccuracy and lack of quantitative evaluation indexes, such as weak field implementation of actual engineering, less test samples, large result uncertainty, strong subjectivity of test results and the like, short duration of a real-bridge load test, large difference between applied load and actual operation load, and poor local effect of measured results of segment stress and macroscopic deformation.
To achieve these objects and other advantages and in accordance with the purpose of the invention, a method for monitoring and evaluating service performance of a segment-spliced girder bonded joint is provided, comprising:
s1, respectively arranging a plurality of first stress measuring points, a plurality of second stress measuring points, a plurality of third stress measuring points and adjacent section vertical displacement measuring points at the joint positions of suspected defects obtained by cracking defects or nondestructive testing in a 1/4-1/8 beam span length area;
For any joint, a plurality of first measuring points are arranged along the height of the beam across the joint and distributed in a joint section tension zone and a compression zone, a plurality of second measuring points are arranged on key teeth along the height direction of the beam and distributed in the joint section tension zone and the compression zone, and a plurality of third measuring points are simultaneously arranged on key teeth on two sides of the joint along the height direction of the beam and distributed in the joint section tension zone and the compression zone and staggered with the arrangement positions of the second measuring points;
s2, evaluating the service state of the joint based on the monitoring results of the measuring points and a shearing-friction theory;
Based on the shearing-friction theory, assuming that the width of the multi-key tooth joint area is omega, the width of a single joint shearing surface is b, and the height of the single key tooth joint shearing surface is d, the calculation formula of the average shearing stress theory is as follows:
ν=V/bd (1)
σx＝pfy+σNx (2)
Wherein V is the shear stress of the joint section, V is the shearing force of the joint, sigma x is the positive stress of the joint, p is the reinforcement ratio of the reinforcing steel bar penetrating the joint, f y is the yield strength of the joint constraint reinforcing steel bar, sigma Nx is the tensile/compressive stress acting on the joint surface, and the tensile and compressive forces are positive and negative;
According to the shear-friction theory, the calculation formula of the limit shear stress of the joint is as follows, without considering the condition that the joint has initial cracking:
νu＝(φpfy+σNx)μ (3)
Wherein v u is the limit shear stress of the joint, phi is the bearing capacity reduction coefficient, mu is the joint interface friction coefficient;
For the case where the tensile force N u acts on the shear plane a cr and there is an initial crack in the joint, the joint limit shear stress and the joint limit shear load capacity are calculated as follows:
νu＝(φAsfy/Acr-Nu/Acr)μ (4)
or V u/μ＝(φAsfy-Nu) (5)
Wherein V u is the ultimate shear bearing capacity of the joint, A s is the total steel bar area passing through the shear plane, A cr is the joint cross-section area, and N u is the axial compressive load acting on the joint cross-section;
① Interface shear-slip state discrimination
Calculating the shear stress v of the joint section by using the formula (1), comparing the shear stress v with the limit shear stress v u of the joint calculated by the formula (3) or the formula (4) according to the condition that whether the joint has initial cracking or not, and adopting a binarization judging method to formulate an interface shear-slip judging standard as follows:
When v is less than or equal to v u, the interface is not in shear-friction sliding;
when v is greater than v u, the interface is indicated to have shearing-friction sliding;
in addition, the shear force V at the joint can be compared with the joint limit shear bearing capacity V u calculated by the formula (5), and a binarization judgment method is adopted to formulate an interface shear-slip judgment standard as follows:
When V is less than or equal to V u, the interface is not subjected to shear-friction sliding;
When V is more than V u, the interface is indicated to have shear-friction sliding;
② Seam interface open state discrimination based on seam crossing stress test result
Comparing the cross-seam stress test results sigma 1 measured at a plurality of first stress measuring points with the positive stress of the seam calculated by the formula (2), and adopting a binarization discrimination method to formulate a preliminary discrimination standard of the opening or closing state of the seam as follows:
σ 1≤σx, indicating that the seam does not open;
Sigma 1＞σx, indicating that the seam opens;
③ Joint ultimate shear strength determination under joint interface open state
For the test piece with initial cracking, when the reinforcement ratio is high and the shear stress exceeds 5.9MPa, tan phi=1.0, and pf y is less than 0.3f c 'or 10.5MPa, wherein f c' is a cylinder concrete compressive strength design value;
Accordingly, under the open state of the joint, according to the condition that whether the joint has initial cracking or not, the joint limit shear stress v u calculated by the formula (3) or the formula (4) is compared, and a binarization judging method is adopted to formulate a joint shear strength judging standard as follows:
When v is less than or equal to v u, the joint interface shear strength meets the requirement, and the open or closed state of the interface does not influence the shear strength;
When v is greater than v u, the friction slip occurs at the joint due to the reduction of the shear strength of the interface;
④ Determination of joint shear force transmission capability
Calculating the shear stress V of the joint section by using the formula (1), comparing the shear stress V with the joint limit shear stress V u calculated by the formula (3) or the formula (4) according to the condition that whether the joint has initial cracking or not, or comparing the shear force V of the joint with the joint limit shear bearing capacity V u calculated by the formula (5), and adopting a binarization judging method to formulate a judging standard of the joint shear force transmission capacity as follows:
When V is not less than V u or V is not more than V u, and the deviation of vertical stress sigma 3 at two sides of the key tooth seam of the adjacent sections measured at each third stress measuring point is less than 5%, the key tooth seam has strong shear force transmission capability;
⑤ Joint shear force transmission capacity discrimination based on segment vertical displacement test result
When the deviation of the vertical stress sigma 3 at two sides of the key tooth seam of the adjacent sections is larger than 5%, and the opening phenomenon of the local or whole seam is primarily judged, the vertical displacement of the adjacent sections at two sides of the seam or the vertical displacement of each section along the bridge span direction is further monitored, the change rules of the bridge span vertical displacement and the adjacent section vertical displacement deviation amplitude delta 1-Δ2 under the action of different temperatures and operating vehicle loads are obtained and compared, when the local vertical displacement has abrupt change or the section vertical displacement test result has an increasing trend, the joint shear force transmission capacity is reduced, and the joint shear strength is reduced;
⑥ Joint shear rigidity judgment based on segment vertical displacement test result
Shear stiffness of joint of segmental spliced beam K Fν has the following calculation formula:
wherein delta 1、Δ2 is the actual measurement result of the vertical displacement of the adjacent sections at two sides of the joint;
According to the time-varying law (the relation curve of shear rigidity and operation time) or the bearing capacity variation trend (the relation curve of shear rigidity and vehicle load) of the joint shear rigidity K Fν in the bridge operation period, when the joint shear rigidity K Fν of the segment spliced beam has an attenuation trend, the macroscopic shear rigidity degradation of the joint is illustrated, and the structural integrity is affected.
⑦ Key tooth cracking state discrimination based on key tooth stress test result
And respectively comparing the key tooth stress test results sigma 2 measured at the second stress measuring points with concrete cracking stress sigma cr, and adopting a binarization judging method to formulate key tooth cracking state judging standards as follows:
When sigma 2≤σcr, it indicates that the key teeth are not cracked;
when σ 2＞σcr, the key teeth are shown to be cracked.
In the method for monitoring and evaluating the service performance of the key tooth joint of the segment spliced box girder, the method for testing the vertical displacement of the segments comprises the steps of arranging target lamps on adjacent segments of joints with 1/4-1/8 span length area of the girder and suspected defects obtained by cracking defects or nondestructive testing, fixing a camera, clearly displaying images of the target lamps, and obtaining the vertical displacement test results of different segments according to the correlation between pixels of video images and displacement.
Preferably, in the method for monitoring and evaluating the service performance of the key tooth glue joint of the segmental assembled box girder, cameras are arranged on the ground or at the pier top.
Preferably, in the monitoring and evaluating method for the service performance of the key tooth glue joint of the segmental assembled box girder, cameras are arranged at the transverse partition plates at the pier top.
The invention at least comprises the following beneficial effects:
The invention can realize long-term observation of monitoring indexes and joint performance characterization, and mutual verification of nondestructive defect monitoring and load test results, and can comprehensively master segment connection states and performance evolution courses.
The invention can solve the problems of poor feasibility, nondestructive testing result accuracy, lack of verification, load test result application limitation and the like of the current joint service condition lossy testing method.
The invention can overcome the defects of the current joint damage coring and nondestructive testing method, such as weak practical engineering field implementation, less test samples, large result uncertainty, strong subjectivity of test results, short duration of the real bridge load test, large difference between the applied load and the actual operation load, poor local effect of the segment stress and macroscopic deformation actual measurement results, and solves the problems of inaccurate evaluation results of the current joint service performance and lack of quantitative evaluation indexes.
Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention.
Drawings
FIG. 1 is a diagram of key slot geometry characteristics of a segment fabricated beam and stress conditions of the splice;
FIG. 2 is a cross-sectional view of a seam test;
FIG. 3 is a joint stress state station layout;
FIG. 4 is a joint stress state station site layout;
FIG. 5 is a graphical illustration of joint stress state station test results;
FIG. 6 is a field layout of a segment box girder vertical displacement non-contact photoelectric measuring point;
FIG. 7 is a graph of test results of vertical displacement of a section box girder;
Fig. 8 is a graph of test results when local vertical displacement is suddenly changed.
Detailed Description
The present invention is described in further detail below with reference to the drawings to enable those skilled in the art to practice the invention by referring to the description.
For the precast concrete segment spliced beam structure, the reinforcing steel bars of each segment beam are independently arranged, the reinforcing steel bars among the segments are not communicated, and the through prestressed tendons are generally arranged on the top surface and the bottom surface of the segment beam, so that the integrity of the precast concrete segment spliced beam structure is enhanced. The joints are used as weak positions of the segmental spliced girder structure, and in order to ensure the connection strength and durability of the joints, the joints are gradually changed from flat joints, dry joints and wet joints into key tooth glue joints. In view of the fact that the segmental assembled beam structure is in a bending-shearing complex stress state along the long joint section of the beam under the comprehensive actions of load, constant load, temperature and the like of an operation vehicle in the service process, the joint section is in a tensile or compressive and shearing stress state along the high direction of the beam (shown in figure 1), and the joint adhesive wet heat aging performance is prominent along with the continuous increase of the service time of the bridge, so that the local or whole technical condition of the bridge is degraded, the integral performance of the structure is further attenuated, the deformation is increased, and the potential safety risk of the segmental assembled beam structure is improved. In order to grasp the service state of the joint in time and take reasonable safety precautions in time, the application provides a monitoring method for the service performance of the key teeth gluing joint of the section spliced box girder based on the joint shearing force-friction theory, basic data are provided for evaluating the service state of the section spliced girder, the service performance monitoring index types of the section girder with different dimensions are determined according to the stress states (tensile, compressive and shear stress states) of the joint in figure 1 and the deformation characteristics of the section girder, and the monitoring method can realize the functions of long-term service, strong stability, remote data acquisition, transmission and the like, and comprises the following specific implementation steps:
(1) Making a key tooth joint service state monitoring scheme
According to the characteristics of joint stress and vertical deflection deformation along the length direction of the segmental beam, based on the key points of joint shear force-friction theory, namely under the action of shear force, friction sliding can occur at a joint interface, so that the joint state of a 1/4L-1/8L (L is the span length of the beam) area is mainly monitored or detected. When cracking defects appear in joints of the spliced beams of the service sections, namely cracking damage appears along key teeth of the sections at the joint height or adjacent sections, joint test section positions should be laid at the positions. In summary, the joint test section is mainly located in the 1/4L to 1/8L region, and the joint position of the suspected defect obtained by cracking or nondestructive testing is shown in fig. 2.
In each section of the joint test, the stress state of the joint, the key teeth, the sections and the like (the test result is shown in fig. 5) and the vertical deformation of the sections or the relative vertical deformation parameters of the adjacent sections (the test result is shown in fig. 7) are mainly tested according to the stress state of the joint (shown in fig. 1) and the vertical deflection deformation characteristics of the section beams. The test targets and reason profiles are as follows:
① The epoxy resin glue used at the joint has quantitative indexes of tensile, compression and shearing resistance of the bonded joint. In order to judge the open or closed state of the joint, the tensile or compressive stress of the joint is tested under the coupling action of the positive stress and the shear stress of the joint of the segmental beam. The measuring points are distributed in the tension area and the compression area of the joint section along the high-span joint of the beam (as shown in figure 3 a), and the number of the measuring points can be adjusted according to the number of key teeth.
② Under the action of bending and shearing coupling, vertical cracks can be generated at the key teeth of the joint area. In order to judge the cracking state of the joint key teeth, the unidirectional positive stress state of the joint key teeth is tested. Measuring points (shown in figure 3 b) are arranged on the key teeth along the height direction of the beam, the measuring points are distributed in a tension area and a compression area of the joint section, and the number of the measuring points can be adjusted according to the number of the key teeth.
③ With the continuous increase of the service time of the segmental beam, the aging performance of the joint compound develops, and the durability and the service performance of the segmental beam are degraded, so that the joint compound has a declining shear force transmission effect. In order to master the change rule of the shear force transmission effect of the joints of the segment assembly Liang Jiaojie, the vertical stress at two sides of the joints is tested or monitored. And measuring points (shown in figure 3 c) are simultaneously arranged on the key teeth at two sides of the joint along the height direction of the beam, the measuring points are distributed in a tension zone and a compression zone of the joint section, and the positions of the measuring points are staggered with the positions of stress measuring points of the key teeth. The number of measuring points can be adjusted according to the number of key teeth.
④ When the joint state is deteriorated, the local and the whole performances of the segment spliced beams can be changed, and the change amplitude and the rate of the long vertical displacement of the segments Liang Yanliang and the change quantity of the local segment displacement can be reflected in the operation process. Therefore, the joint positions of the joint splicing joint areas (1/4L-1/8L areas) of the section splicing beams of the key stress parts focused on the points and the suspected defects obtained by cracking defects or nondestructive testing are distributed, and the section vertical displacement measuring points are distributed (on-site installation is shown in fig. 4).
⑤ When the change amplitude and the change speed of the vertical displacement of the segment are increased, the dynamic characteristic index (such as frequency) of the overall performance of the reaction structure is further tested. At least three power measuring points are distributed along the beam span on the concerned segment spliced girder bridge, and the girder power characteristic test scheme meets the current relevant standard.
(2) Method for monitoring or detecting service state of adhesive joint of formulated key teeth
In order to grasp the integrity of the upper structure in the operation process of the segmental spliced girder bridge and the evolution rule of the service state of segmental splicing seams, the adopted monitoring or detecting method can meet the functional requirements of long-lasting time, strong stability, remote data wireless acquisition, transmission and the like. Therefore, the bridge joint stress, key tooth stress and shear force transmission stress detection instrument adopts a contact type test method with stronger stability, such as a vibrating wire strain gauge and an arch strain gauge. In order to reflect the dynamic influence of the load of the running vehicle, the acquisition system should meet the frequency-adjustable function. For the segment beam vertical displacement index, a non-contact video image testing technology is adopted in view of the fact that the contact type testing method relates to the fact that the datum points are difficult to lay. The test implementation key points are as follows:
① Laying target lamps along the beam span at each test section or seam adjacent section of great interest (field installation as shown in fig. 6 b);
② The camera is arranged at a basically motionless position, such as the ground, the pier top position and the like, and the target lamp image is clearly displayed (the field installation is shown in fig. 6 a);
③ According to the correlation between the video image pixels and the displacement, obtaining vertical displacement test results (shown in fig. 7) of different sections;
④ The segment Liang Jipin is derived using the segment vertical displacement measurements.
(3) Arrangement of monitoring system for service state of segment key tooth joint seam
According to the monitoring or detecting index and method of the service state of the key tooth bonding joint, a contact type stress measuring point and a non-contact type video displacement measuring point are set on the box girder body, and relevant instruments and meters and photoelectric video equipment are installed. In order to meet the requirements of data acquisition and data transmission in a short time under long-lasting and special conditions, a monitoring system with both wired and wireless network acquisition and transmission functions is formed, and the system specifically comprises the following components:
(4) Key tooth joint shear strength calculation based on shear-friction theory
According to the existing shearing-friction theory and the joint stress characteristics under the combined action of shearing force or shearing force and bending moment, the indexes capable of representing the joint performance mainly comprise shearing strength, ultimate shearing stress, joint sliding and the like.
Assuming a multi-key seam area width ω, a single seam shear plane width b, and a single key seam shear plane height d. The calculation formula of the average shear stress theory is as follows:
ν=V/bd (1)
σx＝pfy+σNx (2)
Wherein V is shear stress, V is joint shearing force, sigma x is joint positive stress, p is reinforcement ratio of reinforcing steel bar penetrating the joint, f y is yield strength of joint constraint reinforcing steel bar, sigma Nx is tensile (compressive) stress acting on joint surface, and the tensile and compressive are positive and negative.
Under the condition that the initial cracking of the joint is not considered, according to the shear-friction theory, the limit shear stress calculation formula is as follows:
νu＝(φpfy+σNx)μ (3)
where v u is the joint limit shear stress, phi is the load-bearing capacity reduction coefficient, mu is the joint interface friction coefficient, and μ=1.4, phi=1.0 is specified according to ACI318-71 section 11.15.
For the shear transfer strength of an initial cracking test piece with tensile stress on a shear surface, the shear transfer strength is conservatively estimated by a shear friction theory of an ACI 318-71.11.5 part and a bearing capacity reduction coefficient phi=1.0 in a shear strength design formula of a PCI DESIGN Handbook 6.1.9 part. Therefore, for the case where the tensile force N u acts on the shear plane a cr and there is an initial crack, the shear stress calculation formula of the shear-friction theory is as follows:
νu＝(φAsfy/Acr-Nu/Acr)μ (4)
or V u/μ＝(φAsfy-Nu) (5)
Wherein V u is the ultimate shear bearing capacity of the joint, A s is the total steel bar area passing through the shear plane, A cr is the joint cross-section area, N u is the axial compressive load acting on the joint cross-section, and phi is the bearing capacity reduction coefficient, taking 0.85.
(5) Seam service state assessment based on monitoring result
In the long-term service process of the segmental assembled box girder, in order to master the service condition and the overall performance of the segmental assembled box girder, the stress performance of the joint needs to be further understood in depth by combining a small amount of damage and nondestructive detection results, and the service state of the joint is comprehensively evaluated from the aspects of defect state and performance. At present, through coring damage and ultrasonic nondestructive detection technology, internal defects of joints, such as joint interface cracking, overall incompact and the like, can be primarily analyzed, but the accuracy of test results and the influence analysis on local and overall service performance are required to be further checked. Therefore, a method for identifying the service state of the joint and calculating and analyzing the relevant characterization indexes of the overall performance analysis of the segmental assembled box girder is formulated, and mainly comprises the steps of joint interface slip state judgment, joint interface opening state judgment, key tooth joint cracking state judgment, joint shear force transmission performance evaluation, joint interface shearing resistance performance evaluation and box girder overall analysis.
① Interface shear-slip state discrimination
Calculating the shear stress v of the joint section by using the formula (1), comparing the shear stress v with the limit shear stress v u calculated by the formula (3) or the formula (4), and judging the joint section by a binarization judging method, wherein the interface shear-slip judging standard is as follows:
when v is less than or equal to v u, the interface does not generate shearing-friction sliding;
When v is greater than v u, the interface is in shearing-friction sliding;
In addition, according to the comparison of the joint section shearing force (the section shearing force acting value is determined according to the acting load) and the ultimate shearing bearing capacity of the formula (5), the interface shearing-sliding judgment standard is as follows by a binarization judgment method:
when V is less than or equal to V u, the interface does not generate shearing-friction sliding;
When V is larger than V u, shearing-friction sliding occurs at the interface;
② Judging the opening state of a joint interface:
When the tension or the tensile stress of the cross joint exceeds the tensile strength of the adhesive joint, the adhesive joint interface of the joint is considered to be cracked or opened. Meanwhile, the ultimate shear strength of the adhesive joint is reduced, and the overall performance of the structure is possibly reduced if the service is continued. In this regard, the open or closed state of the joint interface may be initially determined based on the cross-joint tensile stress or compressive stress of each key slot distributed along the section height. Based on the discrimination result, the joint opening state is comprehensively discriminated by considering the interfacial limit shear strength change.
Adopting a binarization judging method and adopting a formula (2), and making a preliminary judging standard of the opening or closing state of the joint as follows:
σ 1≤σx, indicating that the seam does not open;
Sigma 1＞σx, indicating that the seam opens;
Wherein σ 1 is the cross-seam stress test result. The sigma 1 test result only represents the joint state of the key teeth where the measuring points are located, and the joint opening height or range is judged by combining the joint-crossing stress test result of the key teeth along the beam height. Test results for σ 3 and σ 2 are the same as follows.
③ Joint ultimate shear strength determination in joint open state
And when the joint is in an open state, further judging the shear strength of the joint. Considering the change of the axial compressive stress of the joint section (such as prestress loss and the like) and the cracking state of the joint interface in the service process, and calculating the limit shear stress v u of the joint according to the formula (3) and the formula (4).
The research result of AHofbeck shows that for the test piece with initial cracking, when the reinforcement ratio is high and the shear stress exceeds 5.9MPa, the tan phi is required to take a smaller value and the upper limit of pf y during design. I.e., tan phi = 1.0, pf y less than 0.3f c' or 10.5MPa.
Accordingly, in the presence of the seam open state, the seam shear strength level is determined as follows:
When v is less than or equal to v u, the shear strength of the joint interface meets the requirement, and the open or closed state of the interface does not influence the shear strength of the joint interface;
When v is greater than v u, the shear strength of the interface is reduced, so that friction sliding occurs at the joint.
Therefore, the long-term change trend of the joint shear strength in the bridge operation period should be further combined with the joint shear force transmission capacity discrimination result to perform more accurate discrimination.
④ Judging the joint shear force transmission capacity:
For a segment-spliced beam employing a multi-spline joint, the interface open or closed state can affect the shear transfer capability of the joint, as well as the force and deformation coordination capability of the local or overall structure. In the long-term operation process of the bridge, under the influence of the wet heat aging phenomenon of interface adhesive, the axial stress (such as prestress loss) of the joint section and the like, the shear strength of the joint interface is degraded, and the shear transfer capacity of the bridge is directly influenced. Therefore, the joint shear force transmission capacity is determined by combining the joint limit shear stress calculation result v u (considering the joint sigma Nx change) and the vertical stress sigma 3 at two sides of the adjacent segment key tooth joint. The joint shear force transmitting ability was judged as follows:
When V is not less than V u or V is not less than V u, meanwhile, the vertical stress sigma 3 on two sides of the key tooth seam of the adjacent sections is basically consistent (the vertical stress deviation on two sides of the key tooth seam of the adjacent sections is less than 5 percent), which indicates that the shear force transmission capability of the key tooth seam is strong;
When the deviation of the vertical stress sigma 3 at two sides of the key tooth seam of the adjacent sections is larger than 5%, the shear force transmission capability of the key tooth seam cannot be described to be weakened, and the joint shear force transmission capability should be comprehensively judged by further combining the ② seam open state, the macroscopic section vertical deformation test result (the vertical deformation of the adjacent sections at two sides of the non-contact seam) and the like.
⑤ Joint shear force transmission capacity discrimination based on segment vertical deformation test result
When the deviation of the vertical stress sigma 3 on two sides of the key tooth seam of the adjacent sections is larger (more than 5%), and the opening phenomenon of the local or whole seam is primarily judged, the vertical displacement (delta 1、Δ2) of the adjacent sections on two sides of the seam or the vertical displacement (delta 1,Δ2...ΔN) of the sections along the bridge span direction can be further monitored, the change rules of the bridge span vertical displacement and the adjacent section vertical displacement deviation amplitude (delta 1-Δ2) under the action of different temperatures and the load of an operation vehicle are obtained and compared, and when the local vertical displacement has abrupt change (shown in fig. 8) or the test result of the section vertical displacement has an increasing trend, the joint shear force transmission capacity is reduced, and the shear strength of the seam is reduced. In the long-term operation process, because the load of the operation vehicle is basically consistent with the environmental condition, under the same value standard (such as the same temperature, the same load condition, the maximum value or the average value of a certain period of time, and the like), the variation of the vertical displacement of a certain position is basically kept constant. When the vertical displacement of the monitoring position has an increasing trend in the long-term monitoring process, real-time monitoring or periodical monitoring is generally adopted, and the vertical displacement can be distinguished by looking at a time-varying rule curve.
⑥ Joint shear stiffness analysis based on segment vertical deformation test results
When the judging result of the joint service state has the phenomena of joint opening, limit shear force reduction, shear force transmission capacity attenuation, key tooth cracking and the like, the influence of the joint defect on the local and the whole performance of the segmental beam, including the rigidity, the deformation, the strength and the like of the spliced beam, wherein the macroscopic shear rigidity of the joint section is one of key indexes. The macroscopic shear stiffness of the joint section can also characterize the shear transfer capability of the joint.
The method is characterized in that a vertical displacement test result of the segment spliced beam is obtained based on a non-contact photoelectric video test technology, and the shear rigidity K Fν of the joint of the segment spliced beam is calculated according to the following formula:
K Fν is the shear rigidity of the joint of the section assembled beam, delta 1、Δ2 is the actual measurement result of the vertical displacement of the adjacent sections at two sides of the joint, and the measuring points are positioned at two sides of the joint as much as possible.
By comparing macroscopic shear rigidity calculation results under different running vehicle load conditions and joint service conditions, if the results are attenuated, the shear rigidity degradation of the joint is demonstrated, the structural integrity is reduced, and the shear capacity and the shear transfer capacity of the joint are comprehensively judged by combining the judging results of joint opening, shear transfer effect, interface friction and slippage and the like.
⑦ Key tooth cracking state discrimination based on key tooth stress test result
For the service segment spliced beams, the key teeth can improve the shearing resistance of joints. Under the combined action of bending moment and shearing force, the joint key teeth have potential risk of cracking, especially in the shearing force control area (1/8L-1/4L). The key teeth are cracked, so that the shearing resistance of local joints can be reduced, and the overall performance of the segment spliced beam structure is further affected. Therefore, in order to timely grasp the level of the shearing resistance of the key teeth or the overall service state of the joint in the bridge operation process, the stress sigma 2 of the key teeth of the joint is detected or monitored, the cracking state and the cause of the key teeth are analyzed according to the change trend, and the discrimination criteria of the cracking state of the key teeth are formulated as follows:
When sigma 2≤σcr shows that the key teeth are not cracked, wherein sigma 2 is a key tooth stress test result, and sigma cr is a concrete cracking stress.
When σ 2＞σcr, the key teeth are shown to be cracked.
And when the key tooth stress reaches the cracking strength, comprehensively judging the service state of the joint by combining ①～⑤ joint state judging results.
⑧ Mechanical property analysis of segmental spliced beam based on joint stress state test result
In order to further grasp the influence of the joint state on the mechanical property of the whole section assembled beam and the evolution rule of the mechanical property, a finite element simulation method is generally adopted, and units capable of reacting the mechanical property characteristics and the service state of the joint are established in a finite element numerical model of a refined three-dimensional entity of the section assembled beam and are endowed with a corresponding theoretical constitutive model. Wherein the friction unit properties employed based on the joint shear-friction theory are applicable to the joint unit. Therefore, the accurate input of parameters such as the ultimate shear stress, the friction coefficient and the like of the joint friction unit is a key for obtaining an accurate analysis result.
Firstly, considering the penetration condition of joint anchoring steel bars and prestress and the prestress loss condition in the operation process, calculating the positive stress value of the section according to a formula (1), and respectively obtaining the joint limit shear stress and the joint interface friction coefficient according to formulas (3) and (4) aiming at different service states (an initial uncracked state and a cracked state). And then, inputting the key parameters of the determined friction unit attributes into a model, further analyzing the evolution process and change rule of the local and the whole mechanical properties of the segmental spliced beams in different stress states, comparing the finite element numerical simulation result with the field test result, verifying the rationality and the accuracy of the segmental spliced beam refined finite element numerical model, and simultaneously, verifying the accuracy of the joint service state identification result based on the joint stress test result.
⑨ Mechanical property analysis of segmental spliced beam based on vertical deformation test result
Besides adopting a segment spliced beam refined three-dimensional entity finite element numerical model to perform performance analysis, assessment and prediction on the spliced beams, beam unit simulation can be adopted, so that a segment beam seam mechanical model can be introduced into a spring connection unit, and a corresponding theoretical constitutive model is given to the segment beam seam mechanical model. Wherein it is critical to give the connecting unit tangential stiffness accurately. Therefore, based on joint shear rigidity analysis results of the segment vertical deformation test results and segment limit shear bearing capacity calculation results, corresponding unit model parameters can be obtained. The determined key parameters of the connection unit attributes are then entered into the model. The normal rigidity can be determined according to a calculation formula of the ultimate tensile strength (formula 2) of the adhesive joint and the elastic modulus of epoxy glue, and the tangential rigidity can be determined according to a formula of the ultimate shear strength (5) and a formula of the shear rigidity of the joint under a certain state (6), and corresponds to macroscopic shear rigidity in an initial uncracked state and a cracked state respectively. And further analyzing the evolution process and change rule of the local and the whole mechanical properties of the segmental spliced beams in different stress states, comparing the finite element numerical simulation result with the field test result, verifying the rationality and the accuracy of the finite element numerical model of the segmental spliced beams, and simultaneously, verifying the accuracy of the joint service state identification result based on the joint deformation test result.
Aiming at the multi-key tooth adhesive joint of the segmental assembled box girder, the invention provides a joint service performance monitoring and evaluating method based on a shearing-friction theory, and adopts a contact type, non-contact type stress and deformation testing method, a wireless network transmission technology and a cloud platform technology, thereby realizing the requirements of short-duration and long-duration static and dynamic acquisition. The method overcomes the application limitations of the current joint damage coring and nondestructive testing method, such as weak field implementation, less test samples, large result uncertainty, strong subjectivity of test results, and the like, and the characteristics of short duration of a real bridge load test, large difference between applied load and actual operation load, poor local effect of segment stress and macroscopic deformation actual measurement results, and the like, and the test results are inconvenient for evaluating and applying the service state of the multi-key tooth glued joint.
Aiming at the multi-key tooth adhesive joint of the segmental assembled box girder, a joint service performance monitoring and evaluating method based on a shearing-friction theory is provided. Aiming at the requirements of joint service state test and service performance evaluation thereof, under the guidance of a shear-friction theory, a joint service performance monitoring scheme is provided, including monitoring indexes, monitoring methods, monitoring systems and the like. According to the scale and precision requirements of seam service performance monitoring indexes, the contact type, non-contact type stress and deformation testing method and the wireless network transmission and cloud platform technology are comprehensively adopted, so that the short-duration and long-duration, static and dynamic acquisition functions are realized. And on the basis of the performance test results of the joints with different scales, the service states and performances of the joints are judged by combining the typical limit state calculation results.
Unlike the prior art aspects:
1) Arranging surface strain gauges in key tooth joint areas in the box, arranging vibrating wire type or resistance type large deformation strain gauges according to long-term, short-term and joint stress state test requirements, and staggering different strain measuring points according to field conditions;
2) The non-contact type segment vertical deformation testing technology is adopted, wherein key tooth joint positions are focused in the box, vertical displacement of adjacent segments is tested, and the testing positions are respectively arranged in the middle of the segments and close to the joint positions. According to the power distribution condition in the box, corresponding active or passive target lamps are configured, a video image acquisition device is arranged at a pier top fixed position, and the acquisition system can realize the frequency adjustable function so as to meet the adoption requirements of different time periods and different durations.
3) Wireless network transmission and wired data transmission, namely, a limited and wireless acquisition system can be configured in view of weak in-box network signals and meeting short-term and long-term monitoring requirements;
4) The cloud platform technology is that the data is collected through a remote signal receiving and processing system, real-time display is realized in a cloud platform data management module, and time-displacement and time-stress time history curves can be extracted.
5) And the static and dynamic acquisition adjustable functions are realized by installing a portable wireless intelligent static and dynamic acquisition system, connecting the measuring points to the corresponding acquisition system according to acquisition requirements, changing the data acquisition frequency and realizing the dynamic and static acquisition functions.
The application provides a joint service performance monitoring and evaluating method based on a shearing-friction theory, which overcomes the defects of the current joint service performance evaluation result of inaccuracy and lack of quantitative evaluation indexes, such as weak field implementation of actual engineering, few test samples, large result uncertainty, strong subjectivity of test results and the like, short duration of a real bridge load test, large difference between applied load and actual operation load, poor local effect of segment stress and macroscopic deformation actual measurement results and the like of the current joint damage coring and nondestructive testing method. The method comprises the following steps:
step 1:
And (5) making a key tooth joint service state monitoring scheme. The method mainly aims at the joint of the section box girder 1/4 span, 1/8 span region and the section joint of the cracking defect region, and determines the contents of joint test indexes, measuring point positions, test methods and the like.
Step 2:
according to the actual engineering power distribution condition, the environment condition and the like, selecting a testing instrument, a data acquisition and transmission device and an acquisition data observation device. The system comprises a strain gauge, a wired or wireless dynamic and static acquisition system, a wireless network signal receiver, a voltage stabilizing device, an active or passive target, an active or passive video image acquisition device, a power supply device and the like, and can meet the monitoring requirements of short-duration and long-duration monitoring by a field acquisition data test system and real-time observation equipment.
And 3, arranging measuring points of the bonding joint in the service state of the key teeth.
According to the test scheme, the measuring point positions are defined in the splicing seam area of the section beam, the measuring point positions are polished and cleaned, anchoring measures are installed, and the like. Corresponding instruments and meters are arranged at the measuring point positions, the measuring point instruments and meters are kept at a certain distance and are not mutually interfered, and the measuring point wiring is not influenced by detection and inspection under normal operation conditions. If an external power supply device is used, a safety protection device is needed. The video image acquisition device should be fixed in the position that is difficult for taking place vertical deformation, like mound top diaphragm department. The joint stress and deformation of the segments can be synchronously measured at multiple points, and can be reproduced in real time, so that the monitoring efficiency is greatly improved.
Step 4, debugging a key tooth glue joint service state test system
The instruments, meters, equipment and the like of each measuring point are subjected to field test so as to ensure the normal and stable operation of the instrument, the meter, the equipment and the like. The field acquisition data test system or software can extract the monitoring index time course curve, and clearly display the position of each measuring point, the working state information of the monitoring device and the like.
Step 5, extracting the monitoring data of the service state of the bonding joint of the key teeth
And extracting a time course curve of the monitoring index, including a strain time course curve and a vertical deformation time course curve, and displaying and outputting characteristic time period and time point data through a field acquisition data storage device or a system platform.
Step 6, analyzing the monitoring data of the service state of the bonding joint of the key teeth
And acquiring data extraction results on site to obtain stress and deformation relative value and absolute value test results at different positions. According to the shear-friction theory foundation, the geometric configuration characteristics and the load condition of the actual section assembled box girder, the corresponding glue joint shear stress, the limit shear stress, the tensile (compressive) stress and the limit shear force theory calculation result are calculated and are compared with the actual measurement result.
Step 7, judging the service state of the bonding joint of the key teeth
And comparing the stress and deformation test results with theoretical calculation results, and judging the shearing and tensioning states of the key tooth seams, the bonding or opening states of the seams, the interface sliding states and the like.
Although embodiments of the present invention have been disclosed above, it is not limited to the details and embodiments shown and described, it is well suited to various fields of use for which the invention would be readily apparent to those skilled in the art, and accordingly, the invention is not limited to the specific details and illustrations shown and described herein, without departing from the general concepts defined in the claims and their equivalents.

Claims (4)

1.节段拼装箱梁键齿胶接缝服役性能监测和评定方法，其特征在于，包括：1. A method for monitoring and evaluating the service performance of key-tooth adhesive joints of segmental assembled box girders, characterized by comprising: S1、在1/4～1/8梁跨长度区域，以及出现开裂缺损或无损测试获得的疑似缺损的接缝位置分别布设多个第一应力测点、多个第二应力测点、多个第三应力测点和相邻节段竖向位移测点；S1. Arrange multiple first stress measuring points, multiple second stress measuring points, multiple third stress measuring points, and adjacent segment vertical displacement measuring points in the 1/4 to 1/8 beam span area and at joint locations where cracks or defects are present or suspected defects are detected by nondestructive testing. 其中，对于任一所述接缝，多个第一测点沿梁高跨接缝布置，并分布于接缝断面受拉区和受压区，多个第二测点沿梁高方向在键齿上布置，并分布于接缝断面受拉区和受压区，多个第三测点沿梁高方向在接缝两侧的键齿上同时布置，并分布于接缝断面受拉区和受压区，且与多个第二测点的布设位置错开；Wherein, for any of the joints, a plurality of first measuring points are arranged along the beam height-span joint and distributed in the tension zone and compression zone of the joint section; a plurality of second measuring points are arranged on the key teeth along the beam height direction and distributed in the tension zone and compression zone of the joint section; a plurality of third measuring points are arranged simultaneously on the key teeth on both sides of the joint along the beam height direction and distributed in the tension zone and compression zone of the joint section, and are staggered with the layout positions of the plurality of second measuring points; S2、基于上述各个测点的监测结果和剪切-摩擦理论对接缝服役状态进行评定；S2. Evaluate the service condition of the joint based on the monitoring results of each of the above measuring points and the shear-friction theory; 其中，基于剪切-摩擦理论，假定多键齿接缝区宽度为ω，单个接缝剪切面宽度为b，单个键齿缝剪切面高度为d，则平均剪应力理论计算公式为：Based on the shear-friction theory, assuming that the width of the multi-joint joint area is ω, the width of the shear surface of a single joint is b, and the height of the shear surface of a single key tooth gap is d, the theoretical calculation formula for the average shear stress is: ν＝V/bd (1)ν＝V/bd (1) σx＝pfy+σNx (2)σ x ＝pf y +σ Nx (2) 式中，ν为接缝断面剪应力；V为接缝处剪力；σx为接缝处正应力；p为贯穿接缝的钢筋配筋率；fy为接缝约束钢筋的屈服强度；σNx为作用于接缝面的拉/压应力，拉为正、压为负；Where, ν is the shear stress of the joint section; V is the shear force at the joint; σx is the normal stress at the joint; p is the reinforcement ratio of the steel bars running through the joint; fy is the yield strength of the joint restraining steel bars; σNx is the tensile/compressive stress acting on the joint surface, with tension being positive and compression being negative. 根据剪力-摩擦理论，不考虑接缝存在初始开裂的情况，接缝极限剪应力计算公式如下：According to the shear-friction theory, without considering the initial cracking of the joint, the formula for calculating the ultimate shear stress of the joint is as follows: νu＝(φpfy+σNx)μ (3)ν u =(φpf y +σ Nx )μ (3) 式中，νu为接缝极限剪应力；φ是承载力降低系数；μ为接缝界面摩擦系数；Where, νu is the ultimate shear stress of the joint; φ is the bearing capacity reduction coefficient; μ is the friction coefficient of the joint interface; 对于拉力Nu作用于剪切平面Acr，且接缝存在初始开裂的情况，接缝极限剪应力和接缝极限抗剪承载力计算公式如下：When the tensile force Nu acts on the shear plane Acr and the joint has initial cracking, the ultimate shear stress and ultimate shear bearing capacity of the joint are calculated as follows: νu＝(φAsfy/Acr-Nu/Acr)μ (4)ν u =(φA s f y /A cr -N u /A cr )μ (4) 或Vu/μ＝(φAsfy-Nu) (5)Or V u /μ=(φA s f y -N u ) (5) 式中，Vu为接缝极限抗剪承载力；As为穿过剪切面的总钢筋面积；Acr为接缝断面面积；Nu为作用于接缝断面的轴压荷载；Where, Vu is the ultimate shear bearing capacity of the joint; As is the total area of steel bars passing through the shear surface; Acr is the cross-sectional area of the joint; Nu is the axial compressive load acting on the joint section; ①界面剪切-滑移状态判别① Interface shear-slip state determination 应用公式(1)计算接缝断面剪应力ν，根据接缝是否存在初始开裂的情况，与公式(3)或公式(4)计算得到的接缝极限剪应力νu进行对比，采用二元化判别方法，制定界面剪切-滑移判别标准如下：Formula (1) is used to calculate the joint cross-section shear stress ν. Based on whether the joint has initial cracking, it is compared with the joint limit shear stress νu calculated by formula (3) or formula (4). A binary judgment method is used to formulate the interface shear-slip judgment standard as follows: 当ν≤νu，表明界面未发生剪切-摩擦滑移；When ν ≤ ν u , it indicates that no shear-friction slip occurs at the interface; 当ν＞νu，表明界面发生剪切-摩擦滑移；When ν＞ν u , it indicates that shear-friction slip occurs at the interface; 另外，也可根据接缝处剪力V与公式(5)计算得到的接缝极限抗剪承载力Vu进行对比，采用二元化判别方法，制定界面剪切-滑移判别标准如下：In addition, the shear force V at the joint can be compared with the ultimate shear bearing capacity Vu of the joint calculated by formula (5), and a binary judgment method can be used to formulate the interface shear-slip judgment standard as follows: 当V≤Vu，表明界面未发生剪切-摩擦滑移；When V ≤ V u , it indicates that no shear-friction slip occurs at the interface; 当V＞Vu，表明界面发生剪切-摩擦滑移；When V>V u , it indicates that shear-friction slip occurs at the interface; ②基于跨缝应力测试结果的接缝界面张开状态判别② Determination of the opening state of the joint interface based on cross-joint stress test results 分别将多个第一应力测点处测得的跨缝应力测试结果σ1与公式(2)计算得到的接缝处正应力进行比较，采用二元化判别方法，制定接缝张开或闭合状态的初步判别标准如下：The cross-seam stress test results σ1 measured at multiple first stress measurement points are compared with the normal stress at the joint calculated by formula (2). A binary discrimination method is used to formulate the preliminary discrimination criteria for the open or closed state of the joint as follows: σ1≤σx，表明接缝未发生张开现象；σ 1 ≤σ x , indicating that the joint does not open; σ1＞σx，表明接缝发生张开现象；σ 1 >σ x , indicating that the joint is opening; ③接缝界面张开状态下接缝极限抗剪强度判别③ Determination of ultimate shear strength of joints under open joint interface 对于初始开裂的试件，当配筋率高、剪应力超过5.9MPa时tanφ＝1.0，pfy小于0.3f′c或10.5MPa，其中，f′c是圆柱体混凝土抗压强度设计值；For specimens with initial cracking, when the reinforcement ratio is high and the shear stress exceeds 5.9 MPa, tanφ = 1.0, and pf y is less than 0.3f′ c or 10.5 MPa, where f′ c is the design value of the compressive strength of cylindrical concrete; 据此，在接缝存在张开状态下，根据接缝是否存在初始开裂的情况，与公式(3)或公式(4)计算得到的接缝极限剪应力νu进行对比，采用二元化判别方法，制定接缝抗剪强度判别标准如下：Based on this, when the joint is open, according to whether the joint has initial cracking, the joint ultimate shear stress νu calculated by formula (3) or formula (4) is compared, and a binary judgment method is adopted to formulate the judgment standard of joint shear strength as follows: 当ν≤νu，表明接缝界面抗剪强度满足要求，界面张开或闭合状态不影响其抗剪强度；When ν≤ν u , it indicates that the shear strength of the joint interface meets the requirements, and the open or closed state of the interface does not affect its shear strength; 当ν＞νu，表明界面抗剪强度降低造成接缝处发生摩擦滑移；When ν>ν u , it indicates that the interface shear strength decreases, causing friction slip at the joint; ④接缝剪力传递能力判别④ Determination of joint shear force transmission capacity 应用公式(1)计算接缝断面剪应力ν，根据接缝是否存在初始开裂的情况，与公式(3)或公式(4)计算得到的接缝极限剪应力νu进行对比，或根据接缝处剪力V与公式(5)计算得到的接缝极限抗剪承载力Vu进行对比，采用二元化判别方法，制定接缝剪力传递能力判别标准如下：Formula (1) is used to calculate the joint cross-section shear stress ν. Depending on whether the joint has initial cracks, it is compared with the joint ultimate shear stress νu calculated by formula (3) or formula (4), or the joint shear force V is compared with the joint ultimate shear bearing capacity Vu calculated by formula (5). A binary judgment method is used to formulate the judgment standard for the joint shear force transfer capacity as follows: 当ν≤νu或V≤Vu，同时，各个第三应力测点处测得的相邻节段键齿缝两侧竖向应力σ3偏差小于5％，则表明键齿接缝剪力传递能力强；When ν≤ν u or V≤V u , and at the same time, the deviation of the vertical stress σ 3 on both sides of the key tooth gap of adjacent segments measured at each third stress measuring point is less than 5%, it indicates that the shear force transmission capacity of the key tooth joint is strong; ⑤基于节段竖向位移测试结果的接缝剪力传递能力判别⑤ Determination of joint shear force transfer capacity based on segment vertical displacement test results 当相邻节段键齿缝两侧竖向应力σ3偏差大于5％，且初步判别局部或整体接缝存在张开现象，则进一步对接缝两侧相邻节段竖向位移或沿桥跨方向各节段的竖向位移进行监测，获取并对比不同温度、运营车辆荷载作用下的桥跨竖向位移和相邻节段竖向位移偏差幅值Δ1-Δ2的变化规律，当局部竖向位移出现突变或节段竖向位移测试结果有增大的趋势，则说明接缝剪力传递能力降低，接缝抗剪强度衰退；When the deviation of the vertical stress σ3 on both sides of the key-tooth gap between adjacent segments is greater than 5%, and it is preliminarily determined that there is a local or overall joint opening phenomenon, the vertical displacement of the adjacent segments on both sides of the joint or the vertical displacement of each segment along the bridge span direction is further monitored. The variation patterns of the vertical displacement of the bridge span and the deviation amplitude Δ1 - Δ2 of the vertical displacement of adjacent segments under different temperatures and operating vehicle loads are obtained and compared. If there is a sudden change in the local vertical displacement or the segment vertical displacement test results show an increasing trend, it indicates that the shear force transmission capacity of the joint is reduced and the shear strength of the joint is declining. ⑥基于节段竖向位移测试结果的接缝抗剪刚度判别⑥ Determination of joint shear stiffness based on segment vertical displacement test results 节段拼装梁接缝抗剪刚度KFν计算公式如下：The calculation formula for the shear stiffness K Fν of the segmental assembled beam joint is as follows: 式中，Δ1、Δ2为接缝两侧相邻节段的竖向位移实测结果；Where Δ 1 and Δ 2 are the measured results of vertical displacements of adjacent segments on both sides of the joint; 根据桥梁运营期接缝抗剪刚度KFν时变规律或者承载力变化趋势，当节段拼装梁接缝抗剪刚度KFν具有衰减趋势时，则说明接缝处宏观抗剪刚度退化，影响结构整体性；According to the time-varying law of the joint shear stiffness K Fν or the trend of bearing capacity during the operation of the bridge, when the joint shear stiffness K Fν of the segmental assembled beam has a decaying trend, it means that the macro shear stiffness at the joint is degraded, affecting the integrity of the structure. ⑦基于键齿应力测试结果的键齿开裂状态判别⑦ Identification of key tooth cracking status based on key tooth stress test results 分别将多个第二应力测点处测得的键齿应力测试结果σ2与混凝土开裂应力σcr进行比较，采用二元化判别方法，制定键齿开裂状态判别标准如下：The key tooth stress test results σ 2 measured at multiple second stress measurement points are compared with the concrete cracking stress σ cr . A binary discrimination method is used to formulate the key tooth cracking state discrimination standard as follows: 当σ2≤σcr，表明键齿未开裂；When σ 2 ≤σ cr , it indicates that the key teeth are not cracked; 当σ2＞σcr，表明键齿开裂。When σ 2 ＞σ cr , it indicates that the key teeth are cracked. 2.如权利要求1所述的节段拼装箱梁键齿胶接缝服役性能监测和评定方法，其特征在于，节段竖向位移测试方法为：在1/4～1/8梁跨长度区域，以及出现开裂缺损或无损测试获得的疑似缺损的接缝相邻节段布设靶标灯，将相机固定，并清晰显示标靶灯图像，根据视频图像像素与位移的相关关系，获取不同节段的竖向位移测试结果。2. The method for monitoring and evaluating the service performance of the key-tooth adhesive joints of the segmented assembled box beam as described in claim 1 is characterized in that the segment vertical displacement test method is: target lights are arranged in the 1/4 to 1/8 beam span length area and in adjacent segments of the joints where cracks or defects occur or suspected defects are obtained by non-destructive testing, the camera is fixed, and the target light image is clearly displayed, and the vertical displacement test results of different segments are obtained based on the correlation between video image pixels and displacement. 3.如权利要求2所述的节段拼装箱梁键齿胶接缝服役性能监测和评定方法，其特征在于，相机布设在地面或墩顶位置。3. The method for monitoring and evaluating the service performance of the key-tooth adhesive joints of the segmented assembled box beam as described in claim 2 is characterized in that the camera is arranged on the ground or at the pier top. 4.如权利要求3所述的节段拼装箱梁键齿胶接缝服役性能监测和评定方法，其特征在于，相机布设在墩顶横隔板处。4. The method for monitoring and evaluating the service performance of the key-tooth adhesive joints of the segmented assembled box beam as described in claim 3 is characterized in that the camera is arranged at the pier top diaphragm.
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