Seawater dry-wet cycle test method for rubber isolation bearing

Abstract

The invention discloses a seawater dry-wet cycle test method for a rubber shock insulation support, belongs to the technical field of durability test of building materials and structural engineering, and aims to solve the problem that the alternating action of aging and seawater erosion of a marine atmospheric area and a splash zone is difficult to simulate in the prior art. Related samples of the rubber shock insulation support are subjected to periodic high-temperature drying and artificial seawater soaking alternate circulation, and specific test temperature, dry-wet time ratio, artificial seawater components and test speed-up ratio based on the activation energy theory are set; laboratory accelerated simulation of the performance degradation process of actual marine environment service for tens of years to hundreds of years is realized. The mechanical property of a test sample is regularly sampled, the performance degradation rule of the test sample is systematically researched, the simulation environment is real, the acceleration effect is remarkable, the systematicness is high, and a reliable technical means is provided for evaluating and predicting the long-term durability of the rubber isolation bearing in the marine environment.

Description

Technical Field

[0001] This invention relates to the field of durability testing technology for building materials and structural engineering, and more specifically, to a method for testing rubber seismic isolation bearings in seawater wet-dry cycles. Background Technology

[0002] Rubber seismic isolation bearings are key seismic-resistant components in structures such as cross-sea bridges, and their long-term performance is directly related to the safety of the structure. In the marine environment, the bearings are not only affected by thermo-oxidative aging, but also subjected to complex wet-dry cycles due to wave splash, tides, and alternating sunshine and rain. The coupling effect of aging and seawater erosion can significantly accelerate their performance degradation.

[0003] Currently, research on the durability of rubber bearings largely focuses on single factors, such as hot air aging or salt spray testing. These methods cannot realistically simulate the alternating wet and dry processes in actual marine environments, leading to discrepancies between test results and actual service performance. Furthermore, natural exposure testing has excessively long cycles, reaching decades, which is insufficient to meet the urgent needs of engineering design and material improvement. Therefore, developing a testing method that can effectively simulate the alternating wet and dry environment of the ocean and rapidly assess the long-term durability of rubber seismic isolation bearings in the laboratory is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0004] The present invention provides a seawater wet-dry cycle test method for rubber seismic isolation bearings, which aims to solve the problem of how to accurately simulate the key characteristics of the marine environment through artificial acceleration in the laboratory.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A seawater wet-dry cycle test method for rubber seismic isolation bearings includes the following steps: 1) Setting test parameters: setting a constant test temperature, aging-seawater erosion alternation time ratio, artificial seawater, and total test time calculated based on the target service life, material activation energy, and accelerated aging; 2) Cyclic test: placing the relevant samples of the rubber seismic isolation bearings in an environment with a constant temperature, and cyclically performing drying treatment and artificial seawater immersion treatment according to the set alternation time ratio; 3) Performance test: taking samples at preset time points and testing the mechanical properties of the samples according to national standards; 4) Data analysis: analyzing the deterioration law of the performance of the relevant samples of the rubber seismic isolation bearings with test time based on the test results of mechanical properties.

[0007] Furthermore, the test temperature was 80±2℃, and the aging-seawater erosion alternation time ratio was drying time: seawater immersion time = 2:1.

[0008] Furthermore, the artificial seawater contains NaCl: 23.0–24.0 g / kg; MgCl2: 4.8–5.2 g / kg; Na2SO4: 3.8–4.2 g / kg; CaCl2: 1.0–1.2 g / kg; and a salinity of 3.4%–3.6%.

[0009] Furthermore, the calculation of the total test time includes: a) calculating the test acceleration ratio based on the Arrhenius equation of chemical reaction; b) calculating the total test time based on the test acceleration ratio using the accelerated aging formula.

[0010] Furthermore, the test acceleration ratio is defined as... The calculation formula is as follows:

[0011]

[0012] In the formula, is the activation energy; R is the gas constant; This refers to the actual ambient temperature. The test temperature.

[0013] Furthermore, the accelerated aging formula is as follows:

[0014]

[0015] In the formula, Service time in actual environments; This refers to the test time.

[0016] Furthermore, the gas constant R is set to 8.314 J / mol·K; the activation energy is set to 78–90 kJ / mol.

[0017] Furthermore, in step 2, the drying treatment and the artificial seawater immersion treatment are carried out at the same constant temperature, and the seawater immersion ensures that the relevant samples of the rubber seismic isolation bearing are completely submerged.

[0018] Furthermore, the relevant samples of rubber seismic isolation bearings include one or more of the following: an integral rubber seismic isolation bearing, a standard rubber sheet, and a rubber block made of multiple layers of rubber sheets stacked and sealed.

[0019] Furthermore, the mechanical property tests include one or more of the following: hardness, stress at a given elongation, tensile strength, elongation at break, vertical stiffness, horizontal stiffness, and ultimate shear performance.

[0020] The beneficial effects of this invention are as follows:

[0021] 1. This invention reproduces the action mechanism of thermo-oxidative aging, seawater erosion, and alternating wet and dry conditions by matching the wet-dry time ratio, seawater chemical composition, and salinity of the marine environment. It solves the problem of large deviation between traditional single-factor tests and actual service environments. The test results can truly reflect the deterioration law of rubber seismic isolation bearings in the marine environment, thus improving reliability.

[0022] 2. Based on the Arrhenius equation and the calculation of acceleration ratio using specific activation energies of materials, this invention achieves a significant reduction in the test cycle for laboratory compression of natural service time of tens to hundreds of years. At the same time, by using material-adaptive values ​​for activation energies, it ensures that the acceleration process is consistent with the natural degradation mechanism and avoids acceleration distortion.

[0023] 3. This invention covers various sample types, including integral support, standard rubber sheet, and multi-layer rubber block, taking into account both the comprehensive performance under assembled conditions and the microscopic deterioration of rubber materials. At the same time, through multi-time point sampling and multi-dimensional mechanical property testing, a full-dimensional testing system from macroscopic to microscopic and from whole to part is formed, systematically revealing the deterioration mechanism and providing more comprehensive data support. Attached Figure Description

[0024] The present invention will be further described below with reference to the accompanying drawings:

[0025] Figure 1 This is a flowchart of a seawater wet-dry cycle test method for a rubber seismic isolation bearing according to the present invention;

[0026] Figure 2 This is a schematic diagram of the rubber block sample structure and cutting area in this invention;

[0027] Figure 3 This is a schematic diagram of a standard dumbbell-shaped rubber sample in this invention;

[0028] Figure 4 This is a schematic diagram of the rubber seismic isolation bearing sample in this invention. Detailed Implementation

[0029] The present application will now be described in further detail with reference to the accompanying drawings. It should be noted that the following specific embodiments are only used to further illustrate the present application and should not be construed as limiting the scope of protection of the present application. Those skilled in the art can make some non-essential improvements and adjustments to the present application based on the above application content.

[0030] like Figures 1 to 4 As shown, this invention provides a seawater wet-dry cycle test method for rubber seismic isolation bearings. Its core lies in accurately simulating key characteristics of the marine environment through artificial acceleration in a laboratory setting. Specifically, it includes:

[0031] 1. Environmental simulation: Using artificial seawater with specific composition and high temperature conditions, the chemical erosion of seawater and the accelerated effect of high temperature on aging reaction are simulated.

[0032] 2. Process simulation: Through a precisely controlled "drying-soaking" cycle, the alternating processes of sun-dried and splash-eroded areas in the marine atmosphere and wet erosion areas during rainy days are simulated.

[0033] 3. Time Compression: Based on the Arrhenius equation of chemical reactions, by increasing the test temperature and applying the specific activation energy of the materials, the test acceleration ratio is calculated, compressing decades of natural service time into a few months of laboratory time.

[0034] 4. System Evaluation: Not only are the mechanical properties of the entire support tested, but the performance of its constituent rubber materials is also analyzed from the surface to the core, systematically revealing the deterioration patterns and mechanisms.

[0035] The specific experimental steps include:

[0036] 1) Test parameter settings: Set a constant test temperature (80±2℃), an aging-seawater erosion alternation time ratio (drying time: seawater immersion time = 2:1), artificial seawater (containing NaCl: 23.0~24.0g / kg; MgCl2: 4.8~5.2g / kg; Na2SO4: 3.8~4.2g / kg; CaCl2: 1.0~1.2g / kg; salinity 3.4%~3.6%), and a total test time calculated based on the target service life, material activation energy, and accelerated aging.

[0037] The calculation of the total test time includes:

[0038] a. The experimental acceleration ratio is calculated based on the Arrhenius equation for chemical reactions. The experimental acceleration ratio is defined as... The calculation formula is as follows:

[0039]

[0040] In the formula, The activation energy is 78–90 kJ / mol; R is the gas constant, which is 8.314 J / mol·K. This refers to the actual ambient temperature. For the test temperature, the temperature used in this invention is Kelvin (K).

[0041] In this embodiment, the rubber seismic isolation bearing can be a natural rubber bearing or a lead-core rubber bearing, with an activation energy of 80-90 kJ / mol; or a high-damping rubber bearing, with an activation energy of 78-84 kJ / mol.

[0042] b. Based on the test acceleration ratio, the total test time is calculated using the accelerated aging formula, which is as follows:

[0043]

[0044] In the formula, Service time in actual environments; This refers to the test time.

[0045] 2) Cyclic test: Place the relevant samples of rubber seismic isolation bearings in an environment with constant temperature, and perform drying treatment and artificial seawater immersion treatment in a cycle according to the set alternation time ratio. The drying treatment and artificial seawater immersion treatment are carried out at the same constant temperature, and the relevant samples of rubber seismic isolation bearings are completely submerged during seawater immersion.

[0046] 3) Performance testing: Samples are taken at preset time points, and the mechanical properties of the samples are tested according to national standards.

[0047] 4) Data analysis: Based on the test results of mechanical properties, analyze the deterioration law of the performance of relevant rubber seismic isolation bearing samples over test time.

[0048] The rubber seismic isolation bearing related samples in this invention include one or more of the following: the rubber seismic isolation bearing as a whole, a standard rubber sheet, and a rubber block made of multiple layers of rubber sheets stacked and sealed. The mechanical property tests include one or more of the following: hardness, stress at a given elongation, tensile strength, elongation at break, vertical stiffness, horizontal stiffness, and ultimate shear performance.

[0049] Example 1

[0050] 1. Determination of experimental parameters

[0051] This embodiment aims to simulate the effects of seawater wet-dry cycling caused by the complex and harsh marine environment in which rubber seismic isolation bearings are located in near-shore transportation engineering projects such as cross-sea bridges. First, based on relevant specifications and statistical data from literature, parameters such as temperature conditions, wet-dry cycle time ratio, activation energy, experimental acceleration ratio, and artificial seawater composition were determined sequentially, as follows:

[0052] Test temperature ( ): 80℃ (353K); Simulated actual service temperature ( : 20℃ (293K).

[0053] Dry-wet time ratio: 2:1 (determined based on the proportion of sunny and rainy weather in ten coastal cities according to literature statistics, i.e., each cycle is three days, including two days of drying in an aging chamber at 80℃ to simulate the drying process, and then one day of immersion in artificial seawater in the same chamber to simulate the seawater immersion process).

[0054] activation energy( LRB is made of natural rubber and has a strength of 85 kJ / mol.

[0055] Simulated service time ( ): 120 years.

[0056] Test speedup ratio: Substitute the above parameters into the formula In the experiment, the calculated acceleration ratio was 376.

[0057] Test time ( Substitute the above test acceleration ratio into the formula: In the middle, the total test time was calculated. =120 years / 376 ≈ 0.32 years, which is approximately 117 days. For ease of operation, we round it to 120 days.

[0058] Seawater composition and content: NaCl: 23.5 g / kg; MgCl2: 5 g / kg; Na2SO4: 4 g / kg; CaCl2: 1.1 g / kg; salinity: 3.5%.

[0059] 2. Test Plan and Procedures

[0060] First, all samples were placed in an aging chamber at 80 degrees Celsius to begin the first cycle of drying.

[0061] After 48 hours, the prepared artificial seawater was injected into the aging chamber to ensure that the sample was completely submerged, and the soaking stage began.

[0062] Twenty-four hours later, the artificial seawater is drained, and the drying phase begins again. This cycle is repeated until the total experimental time reaches 120 days.

[0063] 2.1 Testing of Integral Rubber Isolation Bearings

[0064] Sampling time points: Sampling tests were conducted on days 0, 15, 30, 45, 60, 75, 90, 105, and 120 of the experiment.

[0065] Test equipment: Electro-hydraulic servo compression-shear test system.

[0066] Test items: Day 0, Day 30, Day 60, Day 90, Day 120: Test vertical stiffness, horizontal stiffness, tensile properties, and ultimate shear properties;

[0067] Days 15, 45, 75, and 105: Test vertical stiffness and horizontal stiffness.

[0068] The specific test conditions are arranged as shown in the table below:

[0069]

[0070] 2.2 Standard Rubber Sheet Sample Testing

[0071] Sampling time: Sampling will be conducted every 3 days until the end of the 120-day trial, with 3 samples taken each time.

[0072] Sample preparation: Three dumbbell-shaped samples were cut from each rubber sheet using a standard cutter, such as... Figure 3 As shown.

[0073] Testing equipment: hardness tester, thickness tester, tensile testing machine.

[0074] Test items: Hardness was tested using a hardness tester; the constant elongation stress corresponding to 30%, 40%, 50%, 100%, 150%, 200%, 250%, and 300% elongation was tested using a thickness tester; tensile strength and elongation at break were tested using a tensile testing machine.

[0075] 2.3 Testing of Multilayer Rubber Block Samples

[0076] Sampling time point: Sampling will be carried out uniformly after the 120th day of the experiment.

[0077] Sample preparation: Mark out the cutting area on each piece and cut out 4 dumbbell samples from each area.

[0078] Test equipment and items: Same standard rubber sheet sample, test hardness, stress at a given elongation, tensile strength, and elongation at break.

[0079] The specific test conditions are arranged as shown in the table below:

[0080]

[0081] The method described in the above embodiments can effectively evaluate the performance degradation trend of rubber seismic isolation bearings after 120 years of service in a marine environment within a 120-day test period, providing key data support for engineering design, bearing selection, and life prediction.

[0082] The above embodiments merely illustrate several implementation methods of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention.

Claims

1. A method for testing rubber seismic isolation bearings using a wet-dry cycle in seawater, characterized in that: The test includes the following steps: 1) Setting test parameters: setting a constant test temperature, aging-seawater erosion alternation time ratio, artificial seawater, and total test time calculated based on the target service life, material activation energy, and accelerated aging; 2) Cyclic test: placing the relevant rubber seismic isolation bearing samples in an environment with a constant temperature, and cyclically performing drying and artificial seawater immersion treatments according to the set alternation time ratio; 3) Performance test: taking samples at preset time points and testing the mechanical properties of the samples according to national standards; 4) Data analysis: analyzing the deterioration law of the performance of the relevant rubber seismic isolation bearing samples with test time based on the test results of the mechanical properties.

2. The seawater wet-dry cycle test method for a rubber seismic isolation bearing according to claim 1, characterized in that: The test temperature was 80±2℃, and the aging-seawater erosion alternation time ratio was drying time: seawater immersion time = 2:

1.

3. The seawater wet-dry cycle test method for a rubber seismic isolation bearing according to claim 1, characterized in that: The artificial seawater contains NaCl: 23.0–24.0 g / kg; MgCl2: 4.8–5.2 g / kg; Na2SO4: 3.8–4.2 g / kg; CaCl2: 1.0–1.2 g / kg; and has a salinity of 3.4%–3.6%.

4. The seawater wet-dry cycle test method for a rubber seismic isolation bearing according to claim 1, characterized in that: The calculation of the total test time includes: a) calculating the test acceleration ratio based on the Arrhenius equation of chemical reaction; b) calculating the total test time based on the test acceleration ratio using the accelerated aging formula.

5. The seawater wet-dry cycle test method for a rubber seismic isolation bearing according to claim 4, characterized in that: The test acceleration ratio is defined as The calculation formula is as follows: ， In the formula, is the activation energy; R is the gas constant; This refers to the actual ambient temperature. The test temperature.

6. The seawater wet-dry cycle test method for a rubber seismic isolation bearing according to claim 5, characterized in that: The formula for accelerated aging is as follows: ， In the formula, Service time in actual environments; This refers to the test time.

7. The seawater wet-dry cycle test method for a rubber seismic isolation bearing according to claim 5, characterized in that: The gas constant R is 8.314 J / mol·K; the activation energy is 78–90 kJ / mol.

8. The seawater wet-dry cycle test method for a rubber seismic isolation bearing according to claim 1, characterized in that: In step 2, the drying treatment and the artificial seawater immersion treatment are carried out at the same constant temperature, and the relevant samples of the rubber seismic isolation bearing are completely submerged during the seawater immersion.

9. The seawater wet-dry cycle test method for a rubber seismic isolation bearing according to claim 1, characterized in that: The relevant samples of the rubber seismic isolation bearing include one or more of the following: the rubber seismic isolation bearing as a whole, a standard rubber sheet, and a rubber block made of multiple layers of rubber sheets stacked and sealed.

10. The seawater wet-dry cycle test method for a rubber seismic isolation bearing according to claim 1, characterized in that: The mechanical property tests include one or more of the following: hardness, stress at a given elongation, tensile strength, elongation at break, vertical stiffness, horizontal stiffness, and ultimate shear performance.

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