How is bridge maintenance and reinforcement technology applied in the new era? What are the implications? Please read the article by the editor of Zhongda Consulting.
Bridge repair and reinforcement refers to the repair of defective bridges and the reinforcement of main load-bearing components to improve the structural performance of the bridge, restore the load-bearing capacity of the bridge structure, improve the safety of bridge applications, and extend the length of the bridge. service life. Bridge maintenance and reinforcement is mainly targeted at Category III or IV bridges or bridges that have been used for a long time. It is an effective measure to make the bridge meet the prescribed load-bearing capacity requirements and usage functions.
With the rapid growth of social traffic volume, higher expectations have been placed on the carrying capacity and passing capacity of bridges. At present, most of the highway bridges in my country have certain defects under the influence of environmental factors and natural disasters. Some highway and bridge management departments pay too much attention to the construction of bridges and ignore the maintenance of bridges. As a result, the performance of the bridges is increasingly declining, and they cannot meet the needs of transportation. Require. Therefore, strengthening the daily maintenance of bridges and repairing and reinforcing bridges that do not meet transportation requirements are of great significance to restoring and improving the safety of bridge operations.
1 Current status and significance of bridge maintenance and reinforcement in the new era
At present, my country's bridge maintenance and reinforcement technology is not mature enough, and relevant theoretical analysis still remains at the level of bridge construction. With the promulgation of a series of highway bridge maintenance specifications such as "Highway Bridge Culvert Maintenance Specifications", "Highway Bridge Reinforcement Design Specifications", and "Highway Bridge Reinforcement Design and Construction Technical Specifications", the damage assessment and repair and reinforcement technology of my country's bridges have gradually been included in standardized management . my country's bridge engineering construction mainly relies on concrete construction as the core technology. Reinforced concrete components are easily deformed due to factors such as temperature, carbonization, acid erosion, chloride ion intrusion, freeze-thaw salt damage, etc., leading to cracks in the bridge deck.
Irrational bridge engineering design is also the main factor affecting the quality of bridges in our country. If the bridge abutment is high or the masonry strength is insufficient, severe deformation of the bridge abutment will occur under strong earth pressure, posing potential traffic safety hazards. Due to certain defects in the design and construction of the bridge, factors such as the pavement layer being too thin, the absence of a steel mesh during the paving process, the interlayer between the pavement and the bridge deck, and the small steel content will affect the driving comfort of the bridge. Bring adverse effects and shorten the overall service life of the bridge. In addition, the installation location of the bridge expansion joint device is unreasonable. Under the repeated action of wheel load, it will cause damage to the bridge expansion joints and affect its economic operation.
Bridge repair and reinforcement is an important part of bridge maintenance. The maintenance and reinforcement of old bridges is obviously different from that of new bridges. It requires comprehensive consideration of the structural design of the bridge itself, the surrounding environment, disease characteristics, capital investment and other aspects. factors. Therefore, the construction difficulty of bridge maintenance and reinforcement is often greater than that of new bridges, whether it is from the reconstruction plan and construction design to the specific implementation of the maintenance and reinforcement plan. After the old bridge has been repaired and reinforced, its structural form, carrying capacity and durability can meet the requirements of transportation. The economic investment is usually 40-50% lower than that of a new bridge, and it has obvious economic and social benefits.
2 Application of repair and reinforcement technology in bridge maintenance
In the process of bridge maintenance, repairing defective and damaged bridges and reinforcing main load-bearing components are the key to restoring and improving the bridge. Effective measures for operational security. Specific measures for repair and reinforcement mainly include bridge deck repair, bridge deck reinforcement layer reinforcement, pasting reinforcement, external prestressed reinforcement, structural system change reinforcement, T-beam section transformation method, fiber reinforced plastic reinforcement and other methods. Bridge deck repair is mainly carried out to repair cracks, holes and falling off on the bridge surface. During the repair process, the damaged part in front is chiseled out and then concrete is refilled. In the case of serious cracks and damage to the bridge deck, the concrete bridge deck should be re-poured, and the damaged parts of the expansion joints should be completely removed to ensure the tightness of the lateral connections between the bridge decks. When laying steel mesh on the bridge deck, attention should be paid to leaving a protective layer under the steel mesh to prevent plain concrete from forming on the pavement layer.
Bridge deck reinforcement layer reinforcement refers to laying a concrete reinforcement layer or reinforced concrete on the basis of the old concrete bridge deck or reinforced concrete to repair the damaged bridge deck and increase the strength of the original beams and slabs. The thickness and bending resistance of the beam and plate are mainly used to repair and strengthen bridge decks that are damaged such as cracks or peeling. Paste reinforcement refers to the application of structural adhesive or glass fiber to the outside of bridge concrete components to fix steel plates and steel bars to improve the load-bearing capacity of concrete components.
The pasting reinforcement method can effectively improve the bending resistance of the reinforced object, and the construction is fast and simple, consuming less material. It has been widely used in bridge maintenance and reinforcement operations in my country. External prestressed reinforcement is mainly used in the maintenance and reinforcement of larger-span bridges. The use performance and load-bearing capacity of the bridge are improved through the application of external prestressed technology. The external prestressed reinforcement method mainly sets thick steel bars in the tension area of ??the lower edge of the bridge to form prestressed steel wire bundles or prestressed tie rods, thereby producing eccentric prestressing for the entire bridge. It uses thick steel bars, high-strength steel wires and other steel materials to strengthen the bridge. External prestressing is applied to the upper part, the construction process is relatively simple, and it does not affect the original structure of the bridge.
T-shaped beam bridge cross-section conversion and reinforcement is a relatively simple method in bridge maintenance and reinforcement. Construction under the bridge can be carried out and the workload is small. When the T-beam bridge's bearing capacity is insufficient, cracks will appear in the tension area of ??the bridge or the bridge span will deflect too much. In this case, the T-beam bridge cross-section conversion method can be used for reinforcement. Changing the structural system reinforcement mainly involves changing the old structural system of the bridge from passive reinforcement to active reinforcement.
Since different bridge structural systems have different stress characteristics, bridge reinforcement is carried out by changing the bridge system, such as the stiffened beam composite beam reinforcement method, the eight-shaped brace reinforcement method, and the bridge-to-culvert reinforcement method. Satisfactory reinforcement effect can be achieved. Fiber-reinforced plastic reinforcement method refers to a method of mixing glass, carbon, plastic and other fibers with epoxy resin adhesive to form fiber-reinforced composite materials, which is used for bridge reinforcement to increase the load-bearing capacity of bridge concrete components and improve the bridge structure. Impact resistance and fatigue resistance, and has good crack resistance.
3 Suggestions on bridge maintenance
3.1 Improve bridge maintenance awareness
In view of the common ideological tendency in bridge maintenance work to attach importance to bridge construction and highway maintenance, we should be corrected. Continuously improve the bridge maintenance awareness of relevant staff and pay equal attention to bridge reconstruction and maintenance. Actively carry out bridge repairs and reinforcements when bridges are damaged or defective, pay attention to daily inspection and maintenance of bridges, detect problems early, and effectively ensure the safety of bridge operations.
3.2 Strengthen the training of staff at all levels
Bridge maintenance is a professional and technical type of work. At present, the highway maintenance management system generally lacks professional skills in bridge maintenance. Personnel and relevant management personnel lack bridge maintenance knowledge and professional skills. In recent years, the level of bridge maintenance management in my country has shown obvious lag due to the serious lack of professional talents. In order to change this situation, relevant departments should strengthen the training of staff at all levels in the highway management department and improve the relevant personnel's knowledge of bridge maintenance. Understand and conduct regular professional and technical training to enable them to master the methods of bridge defect detection, daily maintenance, repair and reinforcement.
3.3 Increase investment in bridge maintenance
Routine inspection of bridge operating conditions requires observation and measurement of the bridge structure and ancillary structures, and some inspections require aerial operations. Advanced and accurate bridge inspection equipment can systematically detect the operating conditions of the bridge, help staff promptly and comprehensively discover bridge defects and damage, and then plan reasonable and effective maintenance plans for specific problems existing in the bridge to ensure the bridge's safety. performance and service life.
4 Summary
In recent years, my country's transportation industry has developed rapidly, and bridges, as an important part of the transportation network, have also made significant achievements. Bridge maintenance and specific Maintenance and reinforcement measures are important factors related to traffic safety. During the bridge repair and reinforcement process, the impact on traffic operations is small. Except for some heavy vehicles that need to be detoured for a short period of time, there is no need to interrupt traffic. The economic investment is small, and the social and economic benefits are obvious.
There are many forms of bridge maintenance and reinforcement technology. Only by scientifically applying maintenance and reinforcement technology can we maximize the use of the bridge's original carrying capacity, reduce maintenance investment, and create ideal maintenance and reinforcement effects.
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