A testing method for the dry joint connection structure of a bridge deck

Abstract

The present invention relates to the technical field of connection structure testing, and in particular to a testing method for the dry joint connection structure of a bridge deck. The method includes preparing a bridge deck specimen with a steel structure embedded dry joint; building a testing device and arranging strain, displacement and pressure sensors in the dry joint area; conducting a graded loading test, including static loading up to 1.5 times the design bearing capacity and dynamic cyclic loading; carrying out an environmental simulation test and repeating the loading under the simulated environment of a temperature and humidity cycling chamber; evaluating the data through a multi-source data fusion optimization algorithm model and calculating indexes such as flexural stiffness and shear stiffness; in addition, a construction stage simulation test is newly added to monitor the alignment deviation of components and the filling density. The present invention can comprehensively evaluate the structural performance, accurately evaluate the key indexes, scientifically predict the durability degradation, innovate the construction simulation, ensure the consistency of the test conditions, realize visualization and verification, and effectively solve the limitation problems of traditional testing methods.

Description

Technical Field

[0001] The present invention relates to the technical field of connection structure testing, and specifically provides a testing method for the dry joint connection structure of bridge decks. Background Art

[0002] In modern bridge engineering construction, the connection quality of bridge decks plays a crucial role in the stability, durability, and load-bearing capacity of the overall bridge structure. The dry joint connection structure of bridge decks has been widely used in various bridge projects due to its advantages such as convenient construction and short construction period. However, this connection structure faces many complex factors during actual service.

[0003] Traditional testing methods for the dry joint connection structure of bridge decks have obvious limitations. On the one hand, most tests only focus on a single environmental parameter, such as only considering the influence of temperature or humidity on the structure, ignoring the coupled effects of multiple factors in the actual environment. This leads to inaccurate evaluation of the long-term performance of the structure in a complex natural environment and cannot provide a reliable basis for the durability design of bridges. On the other hand, previous tests rarely involve the simulation of the construction stage. During the actual installation of dry joints, construction quality problems such as misalignment of components and the compactness of filling materials will significantly affect the final performance of the structure. For example, inaccurate component alignment may lead to uneven stress, and non-compact filling materials are prone to creating weak spots, reducing the overall load-bearing capacity and fatigue resistance of the structure.

[0004] With the development of bridge construction towards large spans and heavy loads, the performance requirements for the dry joint connection structure of bridge decks are increasing. Therefore, a testing method for the dry joint connection structure of bridge decks is proposed to address the above problems. Summary of the Invention

[0005] The purpose of the present invention is to provide a testing method for the dry joint connection structure of bridge decks to solve the problems raised in the above background art.

[0006] To achieve the above purpose, the present invention provides the following technical solutions:

[0007] A testing method for the dry joint connection structure of bridge decks, comprising the following steps:

[0008] S1. Specimen preparation: Prepare a bridge deck specimen containing a steel structure embedded dry joint, which is composed of a pre-embedded steel member, an I-shaped steel member with stiffening plates, a concrete concave-convex tooth shear key, and a UHPC cement-based material covering the steel structure embedded dry joint;

[0009] S2. Setup of the testing device: Fix the bridge deck specimen on the loading platform, and arrange strain sensors, displacement sensors, and pressure sensors in the dry joint area; The arrangement method is as follows:

[0010] S2-1. longitudinally arrange strain sensors along the web and flange plates of the I-shaped belt stiffened steel member;

[0011] S2-2. set displacement sensors at the interface of the concrete concave-convex tooth shear connectors;

[0012] S2-3. arrange pressure sensors at the contact surface between the embedded steel member and the concrete;

[0013] S3. Gradual loading test:

[0014] S3-1. Static load test: Gradually apply vertical load to 1.5 times of the design bearing capacity in stages, and record the strain, displacement and interface pressure data at each stage;

[0015] S3-2. Dynamic cyclic load test: Conduct cyclic loading at a frequency of 0.5 - 5Hz and an amplitude of 30% - 70% of the design load for cycles to monitor the fatigue performance of the joint;

[0016] S4. Environmental simulation test: Place the specimen in a temperature and humidity cycling chamber to simulate the temperature change from -20°C to 60°C and the environment with a humidity of 30% - 95%RH, and repeat the loading test in S3;

[0017] S5. Data evaluation: Based on the load-strain curve, residual displacement and interface pressure distribution, use the optimized algorithm model of multi-source data fusion to calculate the flexural stiffness, shear stiffness, fatigue life and durability degradation coefficient of the joint.

[0018] As an optimal solution, the static load test in step S3-1 includes:

[0019] S3-1-1. In the first stage, load to 50% of the design load and hold for 10 minutes;

[0020] S3-1-2. In the second stage, load to 100% of the design load and hold for 30 minutes;

[0021] S3-1-3. In the third stage, load to 150% of the design load and hold until the specimen fails or reaches a stable state.

[0022] As an optimal solution, the frequency of the dynamic cyclic load in S3-2 is 2Hz, the loading amplitude is 50% of the design load, and the number of cycles is cycles.

[0023] As an optimal solution, the heating and cooling rate of the temperature and humidity cycling chamber in step S4 is 2°C / min, the humidity change rate is 10%RH / min, and each temperature and humidity cycling period is 24 hours.

[0024] As a preferred solution, in step S5, the optimization algorithm model for multi-source data fusion is an improved collaborative dynamic correction algorithm, and the calculation methods for its flexural stiffness and shear stiffness are as follows:

[0025] The flexural stiffness is determined as follows: Divide the sum of the products of each level of load and the corresponding displacement by the sum of the squares of the displacements, and then multiply by the flexural environment correction factor; The flexural environment correction factor is corrected according to the ambient temperature and humidity, and its value is 1 minus 0.005 times the difference between the temperature and 25 degrees Celsius, plus 0.001 times the difference between the humidity and 60%RH.

[0026] The shear stiffness is determined as follows: Divide the sum of the products of the interface shear stress and the corresponding shear displacement by the sum of the squares of the shear displacements, and then multiply by the shear environment correction factor; The shear environment correction factor is corrected according to the ambient temperature and humidity, and its value is 1 plus 0.003 times the difference between the temperature and 20 degrees Celsius, and then minus 0.002 times the difference between the humidity and 50%RH.

[0027] As a preferred solution, the flexural environment correction factor and the shear environment correction factor are calibrated by a hybrid optimization algorithm. The hybrid optimization algorithm combines the genetic algorithm and the particle swarm optimization algorithm, and its fitness function is the minimization of the sum of the absolute errors between the measured values and the predicted values of the flexural stiffness and the shear stiffness. The sum of the absolute errors is the sum of the absolute errors between the measured value and the predicted value of the flexural stiffness plus the sum of the absolute errors between the measured value and the predicted value of the shear stiffness.

[0028] As a preferred solution, the calculation method for the durability degradation coefficient in step S5 is as follows:

[0029] Subtract the shear stiffness after experiencing the environmental cycle from the initial shear stiffness, divide the difference by the initial shear stiffness and multiply by 100%, and then multiply by the environmental acceleration factor considering temperature and humidity;

[0030] The environmental acceleration factor is determined by 1 plus 0.02 times the difference between the temperature and 25 degrees Celsius, plus 0.005 times the difference between the humidity and 60%RH.

[0031] As a preferred solution, it further includes step S6: Construction stage simulation test:

[0032] After the I-shaped stiffened plate steel member is inserted into the embedded steel member, apply a temporary positioning load and monitor the alignment deviation of the member;

[0033] When pouring the UHPC cement-based material, use an ultrasonic flaw detector to detect the filling density, and the void filling rate is required to be ≥95%.

[0034] It can be seen from the technical solution provided by the present invention above that for a test method for the dry joint connection structure of a bridge deck provided by the present invention, the beneficial effects are:

[0035] Comprehensive evaluation of structural performance: Through a complete closed-loop test process covering specimen preparation, various loading tests, environmental simulation, and construction stage simulation, it is possible to comprehensively and deeply evaluate the performance of the dry joint connection structure of the bridge deck from multiple dimensions such as static, dynamic, environmental impact, and actual construction; this provides a strong guarantee for accurately grasping the mechanical behavior of the structure under complex actual working conditions, and can more truly reflect the structural performance compared with traditional single-dimensional test methods;

[0036] Precise algorithm evaluation: An optimized algorithm model of multi-source data fusion such as an improved collaborative dynamic correction algorithm is used to calculate key performance indicators; this algorithm fully considers the coupling effects of environmental factors such as temperature and humidity on the flexural stiffness and shear stiffness of the structure, solves the problem of ignoring environmental factors in traditional methods, and greatly improves the accuracy of performance evaluation; The hybrid optimization algorithm (GA-PSO) is used to calibrate the environmental correction factor, improving the efficiency and accuracy of parameter calibration, making the model prediction value closer to the experimental measurement value, and providing a reliable basis for structural design and performance prediction;

[0037] Reliable durability evaluation: The proposed environmental acceleration factor formula quantifies the non-linear effects of temperature and humidity on durability, and can scientifically predict the durability degradation of the dry joint connection structure of the bridge deck under long-term environmental actions; it fills the gap in long-term performance evaluation, helps to fully consider structural durability in the design stage, extend the service life of the bridge, and reduce long-term maintenance costs;

[0038] Innovative construction simulation: A new construction stage simulation test is added. After the I-shaped stiffened plate steel member is inserted into the embedded steel member, a temporary positioning load is applied and the alignment deviation is monitored, and the filling density of the high-strength cement-based material is detected, which can effectively solve the quality control problems in the actual installation of dry joints; starting from the construction link, ensuring the initial installation quality of the structure, providing a guarantee for the safety of the overall bridge structure, and is an important supplement and innovation to traditional test methods;

[0039] Consistency of test conditions: The design of a special loading fixture ensures the consistency of test conditions; the adjustable clamping mechanism adapts to specimens of different sizes, the hydraulic servo actuator provides high-precision loading force, and the multi-channel data acquisition system synchronously collects sensor data and generates a real-time analysis report, greatly improving the reliability and comparability of test data, and facilitating the comparative analysis and research of test results from different batches;

[0040] Visualization and verification: The test device is equipped with a three-dimensional laser scanner, which can construct a deformation cloud map of the joint area and compare it with the finite element model for verification; this visualization method provides an intuitive basis for structural performance analysis, and at the same time, by comparing with the finite element model, it further verifies the accuracy of the test results and the reliability of the model, promoting the development of bridge structure design and analysis technology. Description of the Drawings

[0041] Figure 1 Schematic diagram of the test method steps for a dry joint connection structure of a bridge deck in the present invention;

[0042] Figure 2 Schematic diagram of the steel structure embedded dry joint structure in the present invention;

[0043] Figure 3 Schematic diagram of the embedded steel component structure in the present invention;

[0044] Figure 4 Schematic diagram of the I-shaped stiffened steel component structure in the present invention;

[0045] Figure 5 Top view of the steel structure embedded dry joint in the present invention;

[0046] Figure 6 Schematic diagram of the bridge deck specimen structure in the present invention.

[0047] In the figure: 1. Bridge deck specimen; 101. Concrete concave-convex tooth shear key; 2. I-shaped stiffened steel component; 201. Web; 202. Flange; 203. Stiffening plate; 3. Embedded steel component; 301. Horizontally perforated steel plate; 302. Concave-convex steel tooth key; 303. Strip groove; 304. Square hole; 4. Stiffened angle steel component. Detailed implementation manners

[0048] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, 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 and are not used to limit the present invention.

[0049] In order to better understand the above technical solutions, the above technical solutions will be described in detail below in conjunction with the drawings of the specification and the specific implementation manners.

[0050] As Figures 1-6 shown, an embodiment of the present invention provides a test method for a dry joint connection structure of a bridge deck, including the following steps:

[0051] S1. Specimen preparation: Prepare a bridge deck specimen 1 including a steel structure embedded dry joint, which is composed of an embedded steel component 3, an I-shaped stiffened steel component 2, a concrete concave-convex tooth shear key 101 and a UHPC cement-based material covering the steel structure embedded dry joint;

[0052] S2. Test device setup: Fix the bridge deck specimen 1 on the loading platform, and arrange strain sensors, displacement sensors and pressure sensors in the dry joint area; The arrangement method is:

[0053] S2-1, strain sensors are arranged longitudinally along the web 201 and flange 202 of the I-shaped steel member 2 with stiffeners;

[0054] S2-2, a displacement sensor is set at the interface of the concrete concave-convex tooth shear key 101;

[0055] S2-3. Install a pressure sensor on the contact surface between the embedded steel member 3 and the concrete;

[0056] S3, hierarchical loading test:

[0057] S3-1. Static load test: Apply vertical load up to 1.5 times the design bearing capacity in stages, and record the strain, displacement and interface pressure data at each stage;

[0058] S3-2, dynamic cyclic load test: cyclic loading is performed at a frequency of 0.5-5 Hz and an amplitude of 30% to 70% of the design load. Second, monitor the fatigue performance of the joint;

[0059] S4, Environmental Simulation Test: Place the specimen in a temperature and humidity cycle chamber, simulating a temperature change from -20°C to 60°C and a humidity environment of 30% to 95% RH, and repeat the loading test of S3;

[0060] S5. Data evaluation: Based on the load-strain curve, residual displacement and interface pressure distribution, an optimization algorithm model with multi-source data fusion is used to calculate the bending stiffness, shear stiffness, fatigue life and durability degradation coefficient of the joint.

[0061] In this embodiment, please refer to Figures 2-6 When preparing the bridge deck specimen 1, the specific specifications and processing of the embedded steel member 3, the I-shaped steel member with stiffening plate 2, and the concrete concave-convex tooth shear member 101 include:

[0062] The embedded steel member 3 is welded from a horizontal perforated steel plate 301 and a steel member with a stiffening angle 4. Each embedded steel member 3 requires one horizontal perforated steel plate 301 and four steel members with a stiffening angle 4, and the welding between the two is in the form of a fillet weld.

[0063] The horizontal perforated steel plate 301 is 380mm long, 350mm wide, and 12mm thick. It has concave and convex steel slits at both ends in the width direction, and a 16mm wide groove with a length of 80mm is opened on one edge in the length direction. A square hole 304 with a length and width of 200mm is opened inside the horizontal perforated steel plate 301, and the four corners of the hole are chamfered. Four circular holes with a diameter of 40mm are evenly opened on both sides of the square hole 304 along the width direction.

[0064] The overall height of the stiffened angle steel member 4 is 119 mm, the thickness of the two side legs is 16 mm, the length of each is 80 mm, and triangular stiffening plates with a thickness of 6 mm are evenly arranged in the middle;

[0065] The middle web of the I-shaped steel member 2 with stiffening plates has a length of 260 mm, a height of 250 mm, and a thickness of 16 mm; the two flange plates 202 on both sides have a length of 180 mm, a height of 250 mm, and a thickness of 16 mm; three stiffening plates 203 are evenly arranged along the height direction of the flange plates 202, with a plate length of 180 mm, a width of 100 mm, and a thickness of 6 mm. Two holes with a diameter of 40 mm are opened in the middle of each stiffening plate 203;

[0066] A strip-shaped groove 303 with a width of 0.2 - 0.5 mm is reserved between the middle web 201 of the I-shaped steel member 2 with stiffening plates and the stiffened angle steel member 4 of the embedded steel member 3 on the side, facilitating the free insertion and removal of the I-shaped steel member 2 with stiffening plates up and down;

[0067] A gap of 5 cm is reserved between the inner surfaces of the two flange plates 202 of the I-shaped steel member 2 with stiffening plates and the end faces of the stiffened angle steel member 4 of the embedded steel member 3, facilitating the filling of UHPC cement-based material;

[0068] A gap of 1 cm is reserved between the outer side of the I-shaped steel member 2 with stiffening plates and the inner surface of the square hole 304 inside the horizontally perforated steel plate 301, facilitating the filling of UHPC cement-based material;

[0069] The concrete concave-convex tooth shear keys 101 are arranged along the thickness direction of the bridge deck specimen 1 at the contact end faces of adjacent two concretes. The sizes of the concrete concave-convex tooth shear keys 101 are complementary on the end faces of the two concretes, and there is no gap between the end faces when the bridge deck specimens 1 are in contact;

[0070] The total length of the dry joint steel structure part is 700 mm, the width is 380 mm, and the height is 250 mm; among them, the I-shaped steel member 2 with stiffening plates can be exactly inserted into two symmetrically placed embedded steel members 3, and UHPC cement-based material is filled in the gap positions of the embedded steel members 3;

[0071] Furthermore, step S1 is to prepare the bridge deck specimen 1 containing the steel structure embedded dry joint. The following is a detailed step description:

[0072] Step S1-1: Material preparation:

[0073] Prepare the corresponding raw materials according to the above specific specification requirements;

[0074] For the embedded steel member 3, prepare the horizontal perforated steel plate 301 that meets the dimensions and the steel for the stiffened angle steel member 4; the horizontal perforated steel plate 301 is selected as a high-quality steel plate with a thickness of 12 mm, and the steel for the stiffened angle steel member 4 is selected to meet the requirement of the thickness of 16 mm for both side legs, as well as the steel with a thickness of 6 mm for making the middle triangular stiffening plate; all steels need to have good weldability and mechanical properties, and after preparation, sampling inspection is carried out to ensure that their yield strength, tensile strength, etc. meet the standards for steel used in building structures;

[0075] For the I-shaped stiffened plate steel member 2, prepare the steel with a thickness of 16 mm for the web and flange plates, and the steel with a thickness of 6 mm for making the stiffening plate 203; strictly control the quality of the steel to ensure that its various performance indicators meet the requirements for steel used in bridge engineering;

[0076] Prepare the formwork materials for making the concrete concave-convex tooth shear key 101. High-strength plastics or customized steel formworks can be selected to ensure that the formwork size accuracy can meet the production requirements of the concrete concave-convex tooth shear key 101, and the key size deviation is controlled within a very small range, such as within ±0.5 mm;

[0077] Purchase UHPC cement-based materials, which should have high fluidity, high strength and good bonding properties to meet the needs of filling voids and ensuring the connection strength of the structure;

[0078] Step S1-2: Processing of the embedded steel member 3:

[0079] Cut and process the horizontal perforated steel plate 301 according to the design dimensions; use a high-precision CNC cutting machine to ensure that the length of the horizontal perforated steel plate 301 after cutting is 380 mm, the width is 350 mm, and the error is controlled within ±1 mm; at both ends in the width direction, use a specific mold or cutting process to make concave-convex steel tooth seams, ensuring that the tooth seam size and shape meet the design requirements, and the error does not exceed ±0.5 mm; on one side edge in the length direction, cut out a groove with a width of 16 mm and a length of 80 mm, and the size error is also controlled within a very small range; use drilling equipment to drill a square hole 304 with a length and width of 200 mm inside the horizontal perforated steel plate 301, and chamfer the four corners of the hole, with the chamfer radius controlled within the design requirements; on the left and right sides of the square hole 304 along the width direction, evenly drill 4 round holes with a diameter of 40 mm, and the drilling position deviation does not exceed ±1 mm;

[0080] Process the stiffened angle steel member 4; first cut out the two side legs so that their lengths are both 80 mm and the thickness is 16 mm, with the error controlled within ±1 mm; then, according to the design, evenly weld the triangular stiffening plates with a plate thickness of 6 mm in the middle position. During the welding process, ensure that the angles and positions of the triangular stiffening plates are accurate, and the weld quality meets the relevant welding standards, without defects such as pores and slag inclusions;

[0081] Weld and assemble one processed horizontal perforated steel plate 301 and four stiffened angle steel members 4; use fillet welds for welding. Before welding, clean and grind the welding parts to remove surface oil, rust and other impurities; use professional welding equipment and weld according to the predetermined welding process parameters to ensure firm welding. The height and width of the weld seam meet the design requirements. After welding, conduct visual inspection and flaw detection of the weld seam. The flaw detection ratio is not less than 30% to ensure welding quality.

[0082] Step S1-3: Processing of I-shaped stiffened plate steel member 2:

[0083] Cut the middle web of the I-shaped stiffened plate steel member 2 to a length of 260 mm, a height of 250 mm, and a thickness of 16 mm, with the cutting error controlled within ±1 mm; cut the two side flange plates 202 to a length of 180 mm, a height of 250 mm, and a thickness of 16 mm, and also ensure the dimensional accuracy.

[0084] Along the height direction on the flange plate 202, evenly arrange 3 stiffening plates 203 according to the design requirements; cut the stiffening plates 203 to a plate length of 180 mm, a width of 100 mm, and a thickness of 6 mm, with the error controlled within ±1 mm; in the middle of each stiffening plate 203, use drilling equipment to drill 2 holes with a diameter of 40 mm, and the deviation of the drilling position does not exceed ±1 mm; then weld the stiffening plates 203 to the flange plate 202. Before welding, process the welding parts, ensure the weld quality during the welding process, and conduct visual inspection after welding.

[0085] At the corresponding side position of the middle web 201 of the I-shaped stiffened plate steel member 2 and the stiffened angle steel member 4 of the embedded steel member 3, use machining processes such as milling to process a strip groove 303 with a depth of 0.2 - 0.5 mm, and control the machining dimensional accuracy within ±0.05 mm to ensure that the I-shaped stiffened plate steel member 2 can be smoothly inserted and removed from the embedded steel member 3.

[0086] Step S1-4: Fabrication and installation of the concrete concave-convex tooth shear key 101 formwork:

[0087] Fabricate a special formwork according to the size and shape requirements of the concrete concave-convex tooth shear key 101; the formwork adopts high-precision machining processes to ensure accurate formwork dimensions and a smooth surface; the concave and convex parts of the formwork are completely matched with the designed shape of the concrete concave-convex tooth shear key 101, with the error controlled within a very small range.

[0088] In the concrete casting mold of the bridge deck specimen 1, the fabricated formwork of the concrete concave-convex tooth shear key 101 is accurately installed on the contact end faces of two adjacent concretes according to the designed positions. During the installation process, measuring tools are used for calibration to ensure the accurate position and firm fixation of the formwork, preventing displacement or deformation during the concrete casting process.

[0089] Step S1-5: Overall assembly and preparation for filling with UHPC cement-based material:

[0090] Assemble the processed I-shaped steel member with stiffening plate 2 and the embedded steel member 3. First, carefully insert the I-shaped steel member with stiffening plate 2 into the 2 symmetrically placed embedded steel members 3, and check whether the 5-cm gap reserved between the inner surfaces of the two flange plates 202 of the I-shaped steel member with stiffening plate 2 and the end faces of the stiffened angle steel members 4 of the embedded steel member 3 meets the requirements, and whether the 1-cm gap reserved between the outer side of the I-shaped steel member with stiffening plate 2 and the inner surface of the square hole 304 inside the horizontal perforated steel plate 301 is accurate. If there are deviations, adjust them in time.

[0091] Check the overall dimensions of the dry joint steel structure part to ensure that the total length of 700 mm, width of 380 mm, and height of 250 mm meet the design requirements. Check and fix the entire assembled structure to ensure its stability and prepare for the subsequent filling of UHPC cement-based material. Before filling the UHPC cement-based material, clean all the gap parts to remove sundries, dust, etc., to ensure the filling effect.

[0092] In this embodiment, step S2 is the link of building the test device, and its detailed description is as follows:

[0093] Step S2-1: Adjustment of the loading platform and placement of the specimen:

[0094] Select a loading platform adapted to the size of the bridge deck specimen 1 and the loading requirements. This platform should have sufficient load-bearing capacity to stably bear a weight far exceeding the expected maximum load of the bridge deck specimen 1 to ensure that the platform does not deform or displace during the whole test process. Use a high-precision level to measure the surface of the loading platform in all directions, and adjust the support feet of the platform to ensure that the flatness deviation of the platform is not more than ±0.5 mm per meter, and build a horizontal and stable loading foundation.

[0095] According to the specific shape and size characteristics of the bridge deck specimen 1, a special fixing fixture is customized; the fixture is made of high-strength alloy steel and is firmly connected to the loading platform through high-strength bolts; the bridge deck specimen 1 is carefully lifted and transported to the preset position on the loading platform, and the adjustable positioning components on the fixture are used, with the help of precise measuring instruments such as total stations, to carefully calibrate the position of the bridge deck specimen 1, so that the dry joint area is precisely located in the central loading area of the loading platform, and the positioning deviation of the bridge deck specimen 1 is controlled within ±5 mm; subsequently, in accordance with the specified tightening torque, an electric torque wrench is used to sequentially tighten the high-strength bolts connecting the fixture and the bridge deck specimen 1 to ensure that the bridge deck specimen 1 will not experience any sliding or displacement during loading;

[0096] Step S2-2: Strain sensor layout operation:

[0097] High-precision fiber Bragg grating strain sensors are used, and their measurement accuracy can reach ±1 με, meeting the precise capture requirements for subtle strain changes; according to the mechanical properties and dimensional parameters of the I-shaped stiffened plate steel member 2, the layout scheme of the strain sensors is planned; on the web 201 of the I-shaped stiffened plate steel member 2, a layout point is determined every 10 cm along the longitudinal direction, starting from one end of the member, and evenly arranged in sequence until the other end; on the flange plate 202, a measuring point is also set every 10 cm along the longitudinal direction, and appropriate densification is arranged at key stress-bearing parts such as the edge of the flange plate 202 and stress concentration to ensure comprehensive and accurate monitoring of the strain conditions of each part of the I-shaped stiffened plate steel member 2;

[0098] Before laying out the sensors, first use sandpaper to polish the surface of the area to be pasted on the I-shaped stiffened plate steel member 2 to remove the surface oil, rust and oxide layer, so that the surface roughness reaches Ra3.2 - Ra6.3 μm to enhance the bonding effect between the sensor and the surface of the I-shaped stiffened plate steel member 2; then, select a special high-strength sensor adhesive, and after preparing the adhesive according to the product instructions, accurately paste the strain sensor on the surface of the I-shaped stiffened plate steel member 2 according to the predetermined position; during pasting, use a high-precision angle measuring instrument to ensure that the parallelism deviation between the axis of the sensor and the longitudinal axis of the I-shaped stiffened plate steel member 2 does not exceed ±1°; after pasting, use a special fixture or tape to temporarily fix the sensor, and wait for at least 24 hours according to the curing time requirements of the adhesive to ensure that the adhesive is fully cured and the sensor is firmly bonded to the I-shaped stiffened plate steel member 2;

[0099] Step S2-3: Displacement sensor installation process:

[0100] Select a linear variable differential transformer (LVDT) displacement sensor to accurately measure the displacement changes at the interface of the concrete concave-convex tooth shear key 101; according to the structural shape and size of the concrete concave-convex tooth shear key 101, symmetrically set displacement sensor installation points at the positions with relatively large relative displacements at the interface of the shear key 101, such as the top and bottom of the concave-convex teeth. At least 2 displacement sensors are installed at each interface of the shear key 101 to simultaneously measure the displacements in different directions of the interface;

[0101] Fabricate a suitable displacement sensor mounting bracket. The bracket is made of lightweight and high-strength aluminum alloy material to ensure sufficient strength and stiffness without adding too much extra weight; through bolt connection or welding, firmly fix the mounting bracket on the concrete foundation on both sides of the concrete concave-convex tooth shear key 101 to ensure that the bracket will not deform or displace during the entire testing process; set a finely adjustable sensor mounting seat on the mounting bracket. With the help of measuring tools such as a micrometer, adjust the position of the mounting seat to keep the measuring rod of the displacement sensor perpendicular to the interface of the concrete concave-convex tooth shear key 101 and maintain a moderate contact pressure of 0.1 - 0.3 N, which can not only accurately measure the interface displacement changes but also avoid damaging the interface; after installation, use a standard displacement gauge to calibrate and debug the displacement sensor to ensure that its measurement accuracy and linearity meet the high-precision requirements of this test;

[0102] Step S2-4: Operation of arranging pressure sensors:

[0103] Select a high-precision thin-film pressure sensor to accurately measure the pressure distribution at the contact surface between the embedded steel member 3 and the concrete; according to the actual contact area and force characteristics between the embedded steel member 3 and the concrete, plan the layout scheme of the pressure sensors, and appropriately increase the number of sensors in the areas with larger contact areas to achieve more accurate measurement of the pressure distribution. Generally, arrange 1 pressure sensor for every 0.1 m 2 of the contact area;

[0104] Before arranging the pressure sensor, first evenly apply a layer of vaseline with a thickness of about 0.1-0.2mm on the contact surface between the embedded steel component 3 and the concrete to reduce the friction between the sensor and the contact surface and ensure that the sensor can accurately sense the pressure; the pressure sensor is accurately pasted on the contact surface of the embedded steel component 3 according to the predetermined position using a special sensor adhesive. During the pasting process, ensure that the sensitive surface of the sensor is completely in contact with the contact surface without bubbles or gaps remaining; after pasting is completed, use waterproof tape to tightly seal the leads of the sensor to prevent moisture from affecting the performance of the sensor during the test; finally, organize the leads of all sensors according to the pre-set numbering sequence, connect them to the data acquisition system, and conduct a comprehensive test and calibration of the entire pressure sensor measurement system to ensure that the sensor works normally, the data acquisition is accurate and reliable, and the pressure data can be collected in real time and accurately.

[0105] In this embodiment, the detailed description of step S3: graded loading test is intended to comprehensively evaluate the mechanical properties and fatigue durability of the bridge deck dry joint connection structure through graded loading of static loads and dynamic cyclic loads. It is specifically divided into the following two stages:

[0106] Step S3-1: Static load test:

[0107] First stage loading (step S3-1-1):

[0108] Select loading equipment: Choose a high-precision, stable hydraulic loading system that can precisely control the loading rate and load size. For example, the loading rate can be precisely controlled within ±0.01 kN / s, and the load measurement accuracy can reach ±0.1% FS.

[0109] Set loading parameters: In the loading system control software, set the loading target to 50% of the design load; start the loading system and slowly apply the vertical load at the set loading rate; during the loading process, closely observe the operation of the specimen and the loading system to ensure that the loading process is smooth and without abnormalities;

[0110] Load holding and data acquisition: When the load reaches 50% of the design load, loading is immediately stopped and the load holding phase begins. The load holding time is set to 10 minutes. During the load holding period, a professional data acquisition system is used to collect data from strain sensors, displacement sensors, and pressure sensors at a frequency of 1 time per minute. The strain sensor is used to measure the longitudinal strain of the web 201 and flange plate 202 of the I-shaped steel member 2 with stiffeners. The displacement sensor monitors the displacement at the interface of the concrete concave-convex shear key 101. The pressure sensor records the pressure at the contact surface between the embedded steel member 3 and the concrete. The collected data will be used to analyze the mechanical response of the structure during this loading phase.

[0111] Second stage loading (Step S3-1-2):

[0112] Continue the loading operation: After the first stage of holding load for 10 minutes ends, start the loading system again, and continue to increase the vertical load at the same loading rate as the first stage; the loading process continues until the load reaches 100% of the design load;

[0113] Prolong the holding time and data monitoring: After the load reaches 100% of the design load, stop loading and enter the holding stage. The holding time is set to 30 minutes; during this period, the data acquisition system continues to collect data of various sensors at a frequency of 1 time per minute; the relatively high load level in this stage can more fully expose the performance characteristics of the structure under near-service loads. By analyzing the collected data, the deformation condition, stress distribution, and overall stability of the structure can be evaluated;

[0114] Third stage loading (Step S3-1-3):

[0115] Load to the ultimate state: After the second stage of holding load for 30 minutes is completed, continue to operate the loading system and slowly increase the vertical load until it reaches 1.5 times the design bearing capacity; the loading process needs to be continuous and stable, and closely monitor the state of the specimen; if obvious failure signs appear on the specimen, such as concrete cracking, excessive deformation of steel members or yielding, etc., stop loading immediately; if within a certain period of time (such as 5 minutes), the deformation of the specimen and the sensor data tend to be stable and there are no obvious changes, it is also regarded as reaching the stable state;

[0116] Comprehensive data recording and observation of failure mode: During the process of loading to the ultimate state and after reaching the stable state, the data acquisition system continuously collects data of various sensors, and increases the data acquisition frequency to 1 time per 10 seconds to obtain more detailed structural response information; at the same time, arrange professional personnel to conduct a comprehensive observation and record of the failure mode of the specimen, including the cracking position of concrete, the crack propagation direction, the deformation parts of steel members, etc.; these data and observation results are crucial for evaluating the ultimate bearing capacity and failure mechanism of the structure;

[0117] Step S3-2: Dynamic cyclic load test:

[0118] Determine the loading equipment: Use an electro-hydraulic servo fatigue testing machine as the dynamic cyclic loading equipment, which can accurately control the loading frequency and amplitude; for example, the frequency control accuracy can reach ±0.01Hz, and the amplitude control accuracy can reach ±0.5%FS;

[0119] Set loading parameters: In the control system of the fatigue testing machine, set the loading frequency between 0.5 - 5 Hz (e.g., set to 2 Hz), and the loading amplitude between 30% - 70% of the design load (e.g., set to 50%); meanwhile, set the number of cyclic loadings to 10 4 - 10 6 times (e.g., set to 5×10 5 times);

[0120] Start loading and real - time monitoring: Start the fatigue testing machine and apply dynamic cyclic loads to the specimen according to the set parameters; during the loading process, use a high - speed data acquisition system to collect data from strain sensors, displacement sensors, and pressure sensors in real - time; set the sampling frequency of the data acquisition system to 100 times per second to ensure that the instantaneous response of the structure under dynamic loads can be accurately captured; meanwhile, closely observe the appearance of the specimen, such as whether new cracks appear, the expansion of existing cracks, and whether there are abnormal deformations on the surface of steel members, etc.;

[0121] Data analysis and fatigue performance evaluation: When the set number of cyclic loadings is completed, stop loading; sort out and analyze the large amount of collected data, and evaluate the fatigue performance of the dry - joint connection structure of the bridge deck by plotting strain - time curves, displacement - time curves, and interface pressure - time curves, etc.; the analysis content includes the prediction of the fatigue life of the structure, the development process of fatigue damage, and the determination of the weak parts of the structure under fatigue loads, etc.; these results are of great significance for evaluating the reliability and durability of the bridge structure under long - term dynamic loads (such as vehicle driving loads).

[0122] In this embodiment, the specific operation steps of step S4 are as follows:

[0123] Step S4 - 1: Prepare the temperature - humidity cycling chamber:

[0124] Select a suitable temperature - humidity cycling chamber:

[0125] According to the size and test requirements of the bridge deck specimen 1, select a temperature - humidity cycling chamber with sufficient space and temperature - humidity control accuracy meeting the requirements; ensure that the temperature - humidity cycling chamber can stably simulate the temperature change range from - 20°C to 60°C and the humidity range from 30% - 95%RH;

[0126] Calibrate the temperature - humidity sensor:

[0127] Before using the temperature - humidity cycling chamber, use a high - precision standard temperature - humidity calibration device to calibrate the temperature - humidity sensor in the chamber; by comparing with the standard value, adjust the measurement deviation of the sensor to ensure the accuracy of temperature - humidity measurement;

[0128] Set the temperature - humidity change parameters:

[0129] In the control system of the temperature and humidity cycling chamber, the heating and cooling rate is set at 2°C / min, the humidity change rate is 10%RH / min, and each temperature and humidity cycle is 24 hours; the setting of these parameters must be carried out strictly in accordance with the requirements of the test method to simulate the temperature and humidity changes that the bridge deck may experience in the actual use environment;

[0130] Step S4-2: Move the test piece into the temperature and humidity cycling chamber:

[0131] Handle the test piece with care:

[0132] Use appropriate handling equipment, such as a flatbed cart with shock-absorbing devices, to ensure that the test piece is not subjected to additional external force impacts or vibrations during the process of moving the bridge deck test piece from the test platform to the temperature and humidity cycling chamber, and avoid damaging the structure of the test piece;

[0133] Fix the position of the test piece:

[0134] Place the test piece at the pre-designed fixed position inside the temperature and humidity cycling chamber and firmly fix the test piece using special fixing jigs; when fixing, it is necessary to ensure that the placement state of the test piece inside the chamber is the same as that during the loading test on the loading platform to ensure the coherence and comparability of subsequent test results;

[0135] Step S4-3: Conduct environmental simulation and loading test:

[0136] Start the temperature and humidity cycle:

[0137] Open the temperature and humidity cycling chamber and make it start running according to the set temperature and humidity change parameters; during the temperature and humidity cycling process, monitor the actual temperature and humidity values inside the chamber in real time to ensure that the deviation from the set values is within the allowable range; if it is found that the temperature and humidity deviation is too large, it is necessary to check the running state of the cycling chamber in time and make adjustments;

[0138] Synchronous loading test:

[0139] When the temperature and humidity cycling chamber starts running, immediately start the loading test equipment and apply vertical loads in stages according to the loading test process in Step S3; in the static load test stage, also load to 1.5 times the design bearing capacity in three stages, hold the load for the corresponding time after each stage, and record the strain, displacement, and interface pressure data of each stage; in the dynamic cyclic load test stage, conduct cyclic loading at a frequency of 0.5 - 5Hz and an amplitude of 30% - 70% of the design load for 10 4 -10 6 times, while monitoring the data related to the joint fatigue performance; during the entire loading test process, it is necessary to ensure that the operation of the loading equipment and the temperature and humidity cycling chamber do not interfere with each other, and the data acquisition system can accurately synchronously collect the temperature and humidity data as well as the test data such as strain, displacement, and pressure;

[0140] Step S4-4: Data Recording and Arrangement:

[0141] Record test data in real time:

[0142] During the environmental simulation and loading test, the data acquisition system shall record the temperature and humidity data in the temperature and humidity chamber and the strain, displacement, interface pressure, etc. data during the loading test in real time according to the set sampling frequency; ensure the integrity and accuracy of the data, and avoid data loss or incorrect recording;

[0143] Arrange the data:

[0144] After a temperature and humidity cycle and the corresponding loading test are completed, arrange the collected data; associate and integrate the temperature and humidity data with the corresponding loading test data in chronological order to form a complete data set; conduct a preliminary analysis of the data to check the rationality and outliers of the data. If there are abnormal data, verify and process them in a timely manner;

[0145] Step S4-5: Multi-cycle cyclic test:

[0146] Repeat the test process:

[0147] After a temperature and humidity cycle and the loading test are completed, without changing the state of the specimen, start the temperature and humidity chamber and the loading test equipment again, and repeat Step S4-3 and Step S4-4 to conduct the environmental simulation and loading test for the next temperature and humidity cycle; through multiple cycles of cyclic tests, the performance change law of the dry joint connection structure of the bridge deck under long-term temperature and humidity changes can be evaluated more comprehensively;

[0148] Evaluate the performance change trend:

[0149] During the test of multiple cycles, compare the data collected at the same stage of different cycles, and analyze the change trends of various performance indicators of the dry joint connection structure of the bridge deck, such as flexural stiffness, shear stiffness, fatigue life, etc.; according to the performance change trend, judge the influence degree of the temperature and humidity environment on the performance of the dry joint connection structure of the bridge deck, and provide a basis for subsequent data evaluation and structural design optimization.

[0150] In this embodiment, the specific operation steps of Step S5 are as follows:

[0151] Step S5-1: Collect and arrange data:

[0152] Summarize sensor data: Summarize all the data collected by strain sensors, displacement sensors, and pressure sensors in step S3 (static load test, dynamic cyclic load test) and step S4 (environmental simulation test); these data cover the response information of the dry joint connection structure of the bridge deck under different loading stages and different environmental conditions; for example, the strain sensor records the longitudinal strain values of the I-shaped stiffened steel member 2 under various load and environmental conditions, the displacement sensor captures the displacement changes at the concrete concave-convex tooth shear key interface, and the pressure sensor feeds back the pressure data at the contact surface between the embedded steel member and the concrete;

[0153] Sort out load data: Sort out the magnitudes of the vertical loads applied at each stage in the static load test, and clarify the load values at each level from 50% to 100% and then to 150% of the design load; at the same time, record the loading frequency (such as 0.5 - 5 Hz), amplitude (30% - 70% of the design load), and number of cycles (10 4 -10 6 times) in the dynamic cyclic load test; in addition, for the environmental simulation test, sort out the temperature range (-20°C to 60°C), humidity range (30% - 95% RH), and cycle period simulated by the temperature and humidity chamber, etc.;

[0154] Establish data association: Based on time, accurately associate the load data, environmental data with the data collected by the sensors; for example, clarify that at a certain moment, what kind of load condition it corresponds to, what kind of temperature and humidity environment it is in, and the specific measurement values of each sensor, forming a complete and ordered data set to provide a basis for subsequent analysis;

[0155] Step S5-2: Plot the load-strain curve:

[0156] Select data points: From the sorted data set, select the strain data points measured by the strain sensor under each level of load during the static load test; for example, when loading to 50% of the design load in the first stage, select the strain data at that moment and at regular time intervals (such as 30 seconds) within 10 minutes of holding the load; similarly, select the corresponding data for the second stage (100% of the design load) and the third stage (150% of the design load);

[0157] Plot the curve: Use the load magnitude as the abscissa and the strain value as the ordinate, and use professional data plotting software (such as Origin, MATLAB plotting tools, etc.) to plot the selected data points one by one in the coordinate system, and generate the load-strain curve through curve fitting algorithms; this curve intuitively shows the strain changes of the steel members in the dry joint connection structure of the bridge deck under different load levels, reflecting the mechanical deformation characteristics of the structure;

[0158] Step S5-3: Determine the residual displacement amount:

[0159] Obtain displacement data: After each stage of the static load test is completed and the holding period ends, and after the dynamic cyclic load test ends, extract the displacement data at the interface of the concrete concave-convex tooth shear key from the data records of the displacement sensors; pay special attention to the remaining displacement value measured by the displacement sensor after unloading.

[0160] Calculate the residual displacement: For the static load test, calculate the residual displacement amounts after unloading from 50%, 100%, and 150% of the design load respectively; the calculation method is the displacement measurement value after unloading minus the initial displacement value before loading; in the dynamic cyclic load test, calculate the residual displacement amount after the cyclic loading ends and unloading; by calculating and analyzing these residual displacement amounts, the deformation recovery ability and cumulative damage degree of the structure after experiencing different load actions can be evaluated.

[0161] Step S5-4: Analyze the interface pressure distribution:

[0162] Process the data of the pressure sensors: Process the data of the pressure sensors arranged on the contact surface between the embedded steel members and the concrete; according to the position distribution of the pressure sensors, classify and sort the collected pressure data according to the corresponding positions; for example, if multiple pressure sensors are arranged in different areas of the contact surface, respectively count the changes in the pressure data of each area under different load and environmental conditions.

[0163] Draw the pressure distribution diagram: Using drawing software, based on the plane graph of the contact surface between the embedded steel members and the concrete, according to the positions of the pressure sensors, visually display the processed data on the graph in the form of color depth or contour lines, etc., to generate the interface pressure distribution diagram; through this distribution diagram, it can be clearly seen the pressure distribution of each part of the contact surface under different load and environmental conditions, judge the pressure concentration area and distribution law, and provide a basis for analyzing the force transmission mechanism and local mechanical properties of the structure.

[0164] Step S5-5: Select the optimized algorithm model for multi-source data fusion:

[0165] Determine the model type: Select the improved collaborative dynamic correction algorithm as the optimized algorithm model for multi-source data fusion; this algorithm can comprehensively consider the influence of environmental factors such as temperature and humidity and load actions on the performance of the dry joint connection structure of the bridge deck, and more accurately evaluate the structural performance by dynamically correcting the flexural stiffness and shear stiffness.

[0166] Clarify the model parameters: Sort out the various parameters involved in the model, such as in the formula (flexural stiffness), (the -th level load), (corresponding to displacement), (shear stiffness), (interface shear stress), (shear displacement), (bending environment correction factor), (Shear environment correction factor), (ambient temperature), (ambient humidity), and (number of static and dynamic test data points), etc.; clarify the physical meaning and value range of each parameter to prepare for subsequent calculations;

[0167] Step S5-6: Calculate bending stiffness :Substitute data: Get the loads at all levels in the static load test from the previously sorted data set and the corresponding displacement Data; at the same time, according to the temperature in the environmental simulation test and humidity Data, calculate the bending environment correction factor , and its calculation formula is ;

[0168] Perform calculations: Substitute the acquired data into the bending stiffness calculation formula First calculate the numerator and the denominator The value of , then multiplied by the bending environment correction factor , thus obtaining the bending stiffness The value reflects the ability of the bridge deck dry joint connection structure to resist bending deformation under environmental factors;

[0169] Step S5-7: Calculate shear stiffness :

[0170] Preparing Data: Collecting Interface Shear Stress in Dynamic Cyclic Loading Tests and shear displacement Data; at the same time, according to the temperature of the environmental simulation test and humidity Data, calculate shear environment correction factor , and its calculation formula is ;

[0171] Perform calculation: Substitute the prepared data into the shear stiffness calculation formula Calculate the numerator in sequence , denominator The value of , then multiplied by the shear environment correction factor , the shear stiffness is obtained Results; Shear stiffness It reflects the ability of the structure to resist shear deformation considering environmental effects;

[0172] Among them, the flexural environment correction factor and the shear environment correction factor are calibrated by a hybrid optimization algorithm, which is the combination of the genetic algorithm and the particle swarm optimization algorithm GA - PSO, and its fitness function is:

[0173] , where is the total error, used to measure the deviation degree between the model predicted value and the actual measured value; 、 are the number of flexural and shear test samples respectively, which are the numbers of samples for flexural stiffness test and shear stiffness test respectively; is the th measured value of flexural stiffness experiment; is the th measured value of shear stiffness experiment; is the th predicted value of flexural stiffness model; is the th predicted value of shear stiffness model;

[0174] Among them, is the flexural stiffness, used to measure the ability of the dry joint of the bridge deck to resist bending deformation; is the th level of load; is the corresponding displacement amount generated under the action of the th level of load; is the shear stiffness, indicating the ability of the dry joint of the bridge deck to resist shear deformation; is the interfacial shear stress; is the shear displacement; is the flexural environment correction factor, and its calculation formula is , used to consider the correction of flexural stiffness by environmental temperature and environmental humidity ; is the shear environment correction factor, and its calculation formula is , used to consider the correction of shear stiffness by environmental temperature and environmental humidity ; is the environmental temperature, used to simulate the temperature value in the environment; is the environmental humidity; 、 are the number of static and dynamic test data points respectively, corresponding to the number of data collected during static load test and dynamic cyclic load test respectively;

[0175] Step S5-8: Evaluate the fatigue life:

[0176] Analyze the dynamic cyclic load data: Deeply analyze the data such as the loading frequency, amplitude, and number of cycles recorded in the dynamic cyclic load test; Combine the fatigue performance parameters of the structural material (such as the S-N curve of the material, which can be obtained through material tests), and use the fatigue life calculation theory (such as Miner's linear cumulative damage theory, etc.) to establish a fatigue damage model;

[0177] Calculate the fatigue life: According to the established fatigue damage model, substitute the dynamic cyclic load test data into the model for calculation; By gradually accumulating the damage caused by each cyclic load to the structure, when the cumulative damage reaches a certain threshold (usually set to 1), the corresponding number of cycles is the predicted value of the fatigue life of the dry joint connection structure of the bridge deck; The evaluation result of this fatigue life is of great significance for predicting the service life of the bridge structure under long-term dynamic loads (such as vehicle driving loads);

[0178] Step S5-9: Calculate the durability degradation coefficient:

[0179] Obtain the shear stiffness data: Extract the initial shear stiffness from the previously calculated shear stiffness results (usually the shear stiffness calculated in the initial state without undergoing environmental cycle tests) and the shear stiffness after experiencing times of environmental cycles ;

[0180] Calculate the environmental acceleration factor: According to the environmental temperature and environmental humidity data in the environmental simulation test, calculate the environmental acceleration factor , and its calculation formula is ;

[0181] Calculate the durability degradation coefficient: Substitute the obtained data into the durability degradation coefficient calculation formula (where, is the durability degradation coefficient , used to characterize the degradation degree of the durability of the dry joint of the bridge deck under the action of the environment; is the initial shear stiffness; is the shear stiffness after experiencing times of environmental cycles; is the environmental acceleration factor, and the calculation formula is , used to consider the accelerating effect of environmental temperature and environmental humidity on durability degradation), first calculate the difference of the numerator , and then divide by Multiply by 100% and finally multiply by the environmental acceleration factor to obtain the durability degradation coefficient value; the durability degradation coefficient is used to measure the degradation degree of the performance of the dry joint connection structure of the bridge deck under long-term environmental effects, providing a quantitative index for evaluating the durability of the structure.

[0182] In this embodiment, the method further includes step S6: construction stage simulation test:

[0183] After the I-shaped stiffened plate steel member 2 is inserted into the embedded steel member 3, apply a temporary positioning load and monitor the alignment deviation of the member;

[0184] When pouring the UHPC cement-based material, use an ultrasonic flaw detector to detect the filling density, and the void filling rate is required to be ≥95%;

[0185] Furthermore, the specific operation steps of step S6: construction stage simulation test are as follows:

[0186] Step S6-1: Apply a temporary positioning load and monitor the alignment deviation of the member:

[0187] Prepare the positioning loading equipment: Select a small hydraulic jack with high precision and stable output force as the temporary positioning load application equipment, whose range should cover the range of 5-10 kN, and be equipped with a high-precision pressure sensor to accurately measure the applied load value in real time; at the same time, prepare the measuring instrument for monitoring the alignment deviation of the member, such as a high-precision total station or electronic theodolite, whose measurement accuracy needs to reach the millimeter level to ensure that the position change of the member during loading can be accurately captured;

[0188] Install the loading equipment and the measuring instrument: After the I-shaped stiffened plate steel member 2 is inserted into the embedded steel member 3, carefully install the hydraulic jack at a position where the horizontal or vertical positioning force can be effectively applied, ensuring that the acting direction of the jack is consistent with the expected positioning direction; Set the total station or electronic theodolite at a suitable observation point to ensure that the characteristic points of the key alignment parts of the I-shaped stiffened plate steel member 2 and the embedded steel member 3 can be clearly observed, such as the edge of the member or the preset measurement mark point;

[0189] Apply the temporary positioning load: Start the hydraulic jack, increase the load at a slow and steady rate, closely watch the reading of the pressure sensor, and stop loading when the load reaches the set value within the range of 5-10 kN; During the loading process, the operator should always pay attention to the state of the member to ensure that no abnormal displacement or deformation occurs;

[0190] Monitoring the alignment deviation of components: Under the state of applying temporary positioning load and maintaining stability, use a total station or electronic theodolite to observe the preset measurement feature points; at certain time intervals, for example, measure once every 2 minutes, and record the coordinate values of the feature points in the horizontal and vertical directions; by comparing the coordinate values at different times before and during the loading, calculate the alignment deviation of the component in each direction; if it is found that the alignment deviation exceeds the allowable range (which can be preset according to the engineering design requirements, for example, the horizontal deviation does not exceed ±5 mm and the vertical deviation does not exceed ±3 mm), it is necessary to adjust the magnitude or direction of the temporary positioning load in a timely manner, or make fine adjustments to the position of the component until the alignment deviation meets the requirements;

[0191] Step S6-2: Detecting the filling density of high-strength cement-based material:

[0192] Select an ultrasonic flaw detector: Select an ultrasonic flaw detector suitable for detecting internal defects in concrete and cement-based materials. This flaw detector should have high-resolution signal reception and processing capabilities and be able to clearly display the reflected wave signals. Its frequency range should be reasonably selected according to the characteristics of the high-strength cement-based material and the expected void size, generally between 50 kHz and 500 kHz; at the same time, prepare a coupling agent for supporting the ultrasonic flaw detector to ensure good contact between the probe and the surface of the material to be detected and reduce signal attenuation;

[0193] Determine the detection points: Before pouring the high-strength cement-based material, formulate a detailed detection point layout plan according to the structural characteristics of the filling space formed by the embedded steel member 3 and the I-shaped stiffened plate steel member 2; the detection points should be evenly distributed in each part of the filling space, with key attention paid to areas prone to voids, such as the corners of the components, areas with dense steel bars, and areas where air may be trapped; use a marker pen to mark each detection point on the surface of the component for subsequent operations;

[0194] Pour the high-strength cement-based material: Accurately prepare the high-strength cement-based material according to the design mix ratio, and use a suitable pouring device, such as a pressure grouting machine, to slowly and continuously pour the material into the void between the embedded steel member 3 and the I-shaped stiffened plate steel member 2; during the pouring process, pay attention to controlling the pouring pressure and speed to avoid material overflow or incomplete pouring; at the same time, adopt appropriate vibration measures, such as using a small vibrating rod or vibrating platform, to vibrate the poured material to remove internal air and improve the filling density;

[0195] Implement ultrasonic flaw detection: After the high-strength cement-based material is poured and reaches a certain curing time (determined according to material characteristics and construction specifications, generally 24 - 48 hours), start the ultrasonic flaw detection; After applying an appropriate amount of coupling agent to the probe of the ultrasonic flaw detector, closely attach it to the detection points on the surface of the component, and according to the operation process of the flaw detector, emit ultrasonic waves into the material and receive the reflected signals; By observing the reflected wave patterns and relevant parameters displayed on the screen of the flaw detector, determine whether there are defects such as voids and holes inside the material at the detection points; For the parts with abnormal reflected wave signals, detailed records need to be made, including information such as the location of the defect, estimated size, and signal characteristics;

[0196] Evaluate the filling density: According to the ultrasonic flaw detection results of all detection points, count the number of points with void defects and compare it with the total number of detection points; Calculate the void filling rate according to the formula: Void filling rate = (Total number of detection points - Number of points with void defects) / Total number of detection points × 100%; If the calculated void filling rate ≥ 95%, it is considered that the filling density of the high-strength cement-based material meets the requirements; If it is lower than this standard, the void defect parts need to be analyzed and corresponding remedial measures need to be taken, such as drilling and grouting repair, etc., and then the detection is carried out again until the void filling rate meets the requirements.

[0197] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A test method for the dry joint connection structure of a bridge deck, characterized in that: It includes the following steps: S1. Specimen preparation: Prepare a bridge deck specimen containing a steel structure embedded dry joint, which is composed of embedded steel components, I-shaped stiffened plate steel components, concrete concave-convex tooth shear components, and UHPC cement-based materials covering the steel structure embedded dry joint; S2. Setup of testing device: Fix the bridge deck specimen on the loading platform, and arrange strain sensors, displacement sensors, and pressure sensors in the dry joint area; The arrangement method is as follows: S2-1. Arrange strain sensors longitudinally along the web and flange plates of the I-shaped stiffened plate steel component; S2-2. Set displacement sensors at the interface of the concrete concave-convex tooth shear component; S2-3. Arrange pressure sensors at the contact surface between the embedded steel component and the concrete; S3. Graded loading test: S3-1. Static load test: Apply vertical load in stages up to 1.5 times the design bearing capacity, and record the strain, displacement, and interface pressure data at each stage; S3-2. Dynamic cyclic load test: Cyclic loading is carried out at a frequency of 0.5 - 5 Hz and an amplitude of 30% - 70% of the design load, lasting times to monitor the fatigue performance of the joint; S4. Environmental simulation test: Place the specimen in a temperature and humidity cycling chamber to simulate the temperature change from -20°C to 60°C and the environment with a humidity of 30% - 95%RH, and repeat the loading test in step S3; S5. Data evaluation: Based on the load-strain curve, residual displacement, and interface pressure distribution, use an optimized algorithm model of multi-source data fusion to calculate the flexural stiffness, shear stiffness, fatigue life, and durability degradation coefficient of the joint.

2. The test method for a dry joint connection structure of a bridge deck according to claim 1, characterized in that: The static load test in step S3-1 includes: S3-1-1. Load to 50% of the design load in the first stage and hold for 10 minutes; S3-1-2. Load to 100% of the design load in the second stage and hold for 30 minutes; S3-1-3. Load to 150% of the design load in the third stage and hold until the specimen fails or reaches a stable state.

3. The test method for a dry joint connection structure of a bridge deck according to claim 1, characterized in that: The frequency of the dynamic cyclic load in S3-2 is 2 Hz, the loading amplitude is 50% of the design load, and the number of cycles is times.

4. The test method for a dry joint connection structure of a bridge deck according to claim 1, characterized in that: In step S4, the heating and cooling rate of the temperature and humidity cycling chamber is 2°C / min, the humidity change rate is 10%RH / min, and each temperature and humidity cycling period is 24 hours.

5. The test method for a dry joint connection structure of a bridge deck according to claim 1, characterized in that: In step S5, the optimized algorithm model of multi-source data fusion is an improved collaborative dynamic correction algorithm, and the calculation methods of its flexural stiffness and shear stiffness are as follows: The calculation formula for flexural rigidity is as follows: , where is the flexural rigidity, is the -level load, is the corresponding displacement, is the number of static test data points, is the flexural environment correction factor, is the ambient temperature, is the ambient humidity, The calculation formula for is The calculation formula for the shear stiffness is as follows: , where is the shear stiffness, is the interfacial shear stress, is the shear displacement, is the number of dynamic test data points, is the shear environment correction factor, The calculation formula for is 6. The test method for a dry joint connection structure of a bridge deck according to claim 5, characterized in that: The flexural environment correction factor and shear environment correction factor are calibrated by a hybrid optimization algorithm, which combines the genetic algorithm and the particle swarm optimization algorithm, and its fitness function is: , where is the total error; , are the number of bending and shear test samples respectively; is the measured value of the -th bending stiffness experiment; is the measured value of the -th shear stiffness experiment; is the predicted value of the -th bending stiffness model; is the predicted value of the -th shear stiffness model.

7. The testing method of a dry joint connection structure for a bridge deck according to claim 1, characterized in that: The calculation method of the durability degradation coefficient in step S5 is: , where is the durability degradation coefficient; is the initial shear stiffness; is the shear stiffness after cycles of environmental exposure; is the environmental acceleration factor, and its calculation formula is .

8. The test method for a dry joint connection structure of a bridge deck according to claim 1, characterized in that: It also includes step S6: Construction stage simulation test: After the I-shaped stiffened plate steel component is inserted into the embedded steel component, apply a temporary positioning load and monitor the alignment deviation of the component; When pouring the UHPC cement-based material, use an ultrasonic flaw detector to detect the filling density, and the void filling rate is required to be ≥95%.

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