On September 14, 2023, led by Southeast University, Technical Specifications for Maintenance and Replacement of Highway Bridge Supports and Expansion Devices (JTG/T) drafted by Highway Science Research Institute of Ministry of Transport, China Communications Highway Planning and Design Institute Co., LTD., Jiangsu Communications Holdings Co., LTD., Changzhou Huarui Special Reinforcement Technology Engineering Co., LTD., Su Communications Group Co., LTD., China and Hong Kong Second Shipping Engineering Bureau Co., LTD 5532-2023), approved by the Ministry of Transport of the People's Republic of China has been officially issued as a recommended industry standard of the People's Republic of China, and implemented since December 1, 2023. The standard was edited by Professor Zhou Minghua, and Huang Yueping, Xu Ming, Guo Tong, Wu Gang and other teachers were the main participants. The formulation and release of the code fill the domestic technical gap to guide and standardize the maintenance and replacement of highway bridge supports and expansion devices, and help to improve the level of scientific bridge management.
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The preparation of this specification is based on the application technology status, disease characteristics, defect causes and maintenance and replacement technology status quo of common bearing and expansion devices of highway Bridges in China. The research team of Southeast University has been through systematic investigation and research, theoretical analysis, test verification and engineering application practice summary for nearly 20 years, and has been approved by experts. It has laid a solid foundation of scientific theory and application practice for the compilation of norms. At the same time, it fully draws on the advanced technology of relevant standards and specifications at home and abroad, and according to the guiding principles of economical applicability, advanced technology, safety and reliability, environmental protection and operability, the maintenance and replacement of common bearings and expansion devices of highway Bridges in China are provided with technical provisions and explanations, providing technical support and decision-making basis for highway bridge maintenance management personnel.
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The main technical highlights and innovation points of this specification
1 Bridge Support
1.1 The inspection, testing and evaluation methods of common bridge supports are standardized
1. What should be checked for different types of supports? And how to check? It's expressed in a list.
2, what should be tested? And how to detect? Qualitative and quantitative detection was carried out according to the disease characteristics and defect degree.
3. What should be assessed? How to assess? This specification proposes to evaluate in three aspects: working condition, adaptability and overall functional failure. Among them, the working status assessment, according to the characteristics of the disease to assess the cause of the bearing disease to determine the nature of the disease, according to the quantitative detection, according to the relevant standards and standards, to assess the degree of defect. Adaptability assessment, according to the specification model selection error, installation error, etc. Overall functional failure is assessed according to failure conditions.
4, the test verified the disease mechanism of plate rubber bearing drum cracking, and put forward the disease treatment method.
5, improve the upper standard of the support inspection, testing and evaluation of the deficiencies and shortcomings.
1.2 Standardized maintenance and maintenance methods for different types of supports
1. The list of technical provisions stipulates the maintenance contents and maintenance methods of different types of supports.
2, using the patented technology developed and researched, the external protection of the outer drum cracking of the plate rubber bearing is verified by practical engineering application, and it is a fruitful method to extend the service life of the support. This is an important innovation.
3. Improve the shortcomings of the upper specifications for support maintenance projects and maintenance methods, and achieve accurate maintenance.
1.3 The support replacement technology has been standardized to fill the gap in domestic standards
1. The key technology of support replacement is the safe jacking technology of bridge. The technical provisions of this code make clear provisions on support replacement design, bridge jacking construction, jacking control technical indicators, construction intelligent monitoring and replacement quality acceptance. Since 2006, the member units of the preparation team have replaced more than 150 bridge supports of different structures, accumulated rich experience through engineering practice and verification, improved the technical provisions of the specification, and made an explanation in the provisions, filling the gap in the domestic bridge support replacement technology.
2. Through engineering practice, the technology of bridge jacking and support safety replacement without interrupting traffic is proposed for the first time in technical provisions.
3. The replacement design and replacement method of the support of the prefabricated component in the form of simple first and then supported continuous bridge structure are specified.
4, the technical provisions for the first time proposed for the curved bridge (curved bridge), inclined bridge and other special structural bridge support replacement design regulations, the influence factors, through engineering verification in the provisions of the description of the system.
5, standardize the construction monitoring when the support is replaced, focusing on the monitoring of the beam body lifting and falling beam two processes. The intelligent monitoring method is proposed and developed for the first time to track and monitor in real time to ensure construction safety.
2 Bridge expansion device
2.1 The inspection, testing and evaluation of telescopic devices are standardized
1. What should be checked? And how to check? According to the results of many years of research, the contents to be checked are specified through the list of technical provisions and the inspection flow chart to prevent omissions.
2, what should be tested? And how to detect? According to the corresponding product standards, the joint width, surface smoothness and roughness, component defects and anchorage concrete cracking damage are quantitatively detected to determine the damage degree, grade and cause of the disease.
3. What should be assessed? And how to evaluate?
The nature and defect grade of the disease were evaluated according to the cause of disease examination and quantitative detection results. As a basis for maintenance and replacement decisions.
2.2 What should the expansion device be maintained? Repair what?
1, the maintenance requirements are specified: keep the surface clean, smooth, no uneven, anchored concrete without cracking damage, waterproof drainage should be no seepage water leakage and water. The investigation found that the expansion device of the comb plate was seriously corroded due to leakage.
2. it is stipulated that the defective parts should be replaced in time, the study found that the premature defect of parts will lead to the loss of the overall function of the telescopic device, and the project verified that the overall function can be restored by replacing the parts and extending the service life. This is an important technical highlight and innovation.
3. The technical requirements for quality control of components including elastic components are specified, and the research finds that the quality control technical indicators and testing methods of parts are missing in the product standards. The technical provisions of this specification, through the test verification, make up for this deficiency.
2.3 Specifications for the replacement of telescopic devices
1, the telescopic device replacement design and product selection requirements.
2, improve the telescopic device replacement when the telescopic amount of review calculation method, research found that many telescopic device damage is due to the telescopic amount of calculation defects, resulting in improper product selection and damage. (Case: Nanjing Yangtze River Bridge No. 2, New Yalu River Bridge, Humen Bridge No. 2)
3, the telescopic device replacement according to the actual situation can be divided into whole replacement or subsection replacement. More than 4 lanes back and forth can be replaced by lane segments without interrupting traffic, and the technical design requirements for segment replacement are specified. (Project case: Shanghai Nanpu Bridge)
2.4 Maturity of the technical provisions of this specification
The technical requirements specified in the technical provisions of this specification have been verified by engineering practice and are all mature technologies.
