CFRP stengthening project - Longevity Palace

Longevity Palace, or Jingyang Temple, is thousands of cities and rural areas across the country, as well as Taiwan, Singapore, Malaysia and other regions and countries. It is also the representative of Chinese ancient hall culture, so it is also called Jiangxi Hall, Jiangxi Temple, Jiangxi Township Hall, Yuzhang Hall, etc. 

The renovation project was carried out in three phases, with a total planned reconstruction area of approximately 20.75 acres and a total investment of 320 million yuan, involving a total carbon cloth of 150,000 square meters. It was the largest carbon fiber cloth reinforcement and reconstruction project in China at that time.

Application of prestressed CFRP plate to strengthen bridge

Project Overview

The project is located on Huancheng Road in Taiyuan City, with an overpass span of 726 m. The net width of the bridge deck is 16.2 m, and the superstructure is prestressed box girder. The bridge was opened to traffic in the 1990s.

After a recent bridge inspection, it was found that the bearing capacity reserve of the bridge has declined seriously, which has begun to threaten the normal service of the bridge. It is determined by the government as an emergency rescue project, and must be dealt with immediately, and at the same time, it requires that the bridge deck be open to traffic during the reinforcement period. 

Therefore, it is planned to use prestressed carbon fiber plate reinforcement technology to complete the structural reinforcement.

Process Principle

(1) By applying prestress to carbon fiber plate, it can maximize the high tensile strength of carbon fiber material. The principle is similar to that of prestressed beam structure. Due to the prestress applied in advance, the material has a certain initial strain. After the second stress, it can improve the coordinated deformation ability of carbon fiber materials and concrete materials to improve the quality and effect of reinforcement.

(2) By applying prestress, decompression bending moment can be generated, which can offset a large part of the early load, improve the bearing capacity of the structure in the later period, significantly improve the crack resistance of the structure, and limit the appearance of new cracks, improve the overall rigidity and strength of the member, reduce the deformation of the bearing deflection.

(3) The deformation of the carbon fiber plate comes from two aspects, one is the deformation caused by the prestress, and the other is the deformation under the external load. The shearing deformation of the adhesive that shares the two parts of the deformation is distributed in the members. The two ends and mid-span positions of the adhesive can evenly distribute the shear deformation of the adhesive and prevent the brittle damage of the adhesive.

(4) For the proposed reinforcement structure, according to the mechanical performance and installation space of the engineering structure, the reinforcement position must be reasonably arranged, and the carbon fiber board coated with special epoxy glue should be used to pre-square the tension, repair the deformation and closed cracks of the component, and then paste the carbon fiber plate to the part of the bottom plate of the component to maximize the load-bearing capacity of the structure.

Bridge reinforcement materials

HM prestressed CFRP plate

HM-120cp carbon fiber plate adhesive

HM-200 chemical anchor bolt

Construction process

Scheme design-site construction preparation-beam bottom repairing and grinding-measurement lofting-drilling and planting reinforcement-anchorage installation-installation of carbon fiber board-stretched carbon fiber board-carbon fiber board coating-carbon board brush coating protection layer, anchoring at both ends of the anchor zone .

Conclusion 

The use of prestressed carbon fiber plate reinforcement technology can be widely applied to many reasons, such as damaged concrete structure, corroded steel bar, load lifting, standard improvement, improper design and construction, changes in use function, etc. In order to extend and improve the service life and capacity of the bridge structure as much as possible, improve the bearing capacity of the structure, and enable the bridge structure to exert higher service requirements, the above bridges must be reinforced and reinforced as necessary. Considering that the use of prestressed carbon fiber plate reinforcement technology has the advantages of simple construction and low technical threshold, only the construction personnel need to have a certain prestress application technology. In addition, the entire construction process does not require the support of large mechanical equipment, and can be completed using only various types of small equipment, such as electric drills, rhinestones and jacks. During the bridge reinforcement construction, since there is no need to close the traffic, it will not affect the normal passage of the bridge deck and will not cause congestion pressure on the local traffic. This article takes case analysis as the main method and summarizes the relevant technologies on the reinforcement of prestressed carbon fiber plate. It has been proved by practice that the use of prestressed carbon fiber reinforcement method at the bottom of the beam can significantly improve the bearing capacity of the bridge, and the construction process has a high cost performance, which is worth further promotion .

Applying structural strengthening technology in buildings

Problems of structural strengthening technology in building application

Relevant staff have insufficient knowledge of structural strengthening technology

In the use of house construction, due to the influence of physical factors, human factors and natural factors, it will shorten the service life of the house and affect the normal use of the house. The house provides people with a place to live, with strong integrity, and the stability of all structural components plays a vital role in the overall quality of the house. In the course of daily use of the house, if the structure of a certain place is damaged, it is very likely that a joint effect will occur, causing damage to other parts of the house, affecting the normal use of the house, and threatening the safety of residents’ lives and property. In the structural design of house buildings, adopting scientific design concepts can avoid the occurrence of such phenomena. During the construction of house buildings, if the construction personnel strengthens the emphasis on structural strengthening technology to ensure the overall quality of the construction, it will improve the quality of the house building. Overall quality. At this stage, many construction workers in my country have not yet realized the importance of structural strengthening technology, which has led to quality problems in the subsequent use of housing construction, resulting in serious safety accidents.

Seismic structure design of houses is unscientific

my country has a vast territory and ranks third in the world in terms of land area. Its geological structure is relatively complex. Some provinces are located in areas where geological disasters occur frequently, and earthquakes and other geological disasters often occur. If an earthquake occurs, it will seriously threaten people's lives and property and cause serious losses to society. In the process of designing housing construction, scientific design methods are adopted to strengthen the emphasis on building structure strengthening technology, improve the building's ability to resist earthquakes and other geological disasters, and reduce the losses caused by earthquakes. When designing the seismic structure of a house, scientific design measures can effectively improve the stability and safety of the building. Even if the earthquake really comes, it can effectively resist the damage caused by the earthquake and create more time for people to escape. At this stage, in the development process of my country's construction industry, the seismic design of buildings designed by designers is not very reasonable and scientific, and the seismic performance of buildings cannot yet reach the ideal standard. When the earthquake really came, due to the unscientific strengthening technology of the building structure, a large area of the building was damaged, threatening the lives and property safety of the residents and restricting the development and progress of the construction industry.

Construction personnel pay less attention to structural durability

In the process of housing construction, human factors can easily cause damage to the building. As the use time of the building increases, the building is prone to aging. The damage caused by the outside world to the building body gradually reduced the quality of the house building. Once the skeleton inside the building is destroyed, it will lead to the destruction of the entire building. Therefore, in the process of construction, designers must pay attention to structural strengthening technology.

Significance of applying structural strengthening technology in buildings

Improve the seismic performance of house construction

Based on the actual situation in China, China has a vast territory and a very complicated geological structure. Many places are located in areas with frequent geological disasters. These areas often have small-scale earthquake disasters, although they will not have a serious impact on people’s lives and property safety. But it will still bring some economic losses.

In traditional structural design of houses, advanced structural strengthening technology is generally not used, resulting in very poor seismic performance of houses. Even if a small-scale geological disaster occurs, the house will be severely damaged, forcing people to invest huge financial resources to renovate the house, causing serious economic losses. In the event of a severe earthquake disaster, houses built using traditional design methods are damaged very quickly, leaving people with little reaction time, which will magnify the losses caused by the earthquake indefinitely. On the contrary, if a scientific design technique is adopted and the building structure strengthening technique is used, the seismic performance of the house is greatly improved. For the less harmful earthquakes, the reinforced houses can successfully resist the earthquake threat, and for the more harmful earthquakes, they can buy more time for people’s escape and provide security for their normal lives.

Extend the life of the house

Due to the vast territory of my country, the climate varies greatly from place to place. The geological structure and climate of different regions are very different. Because of different natural conditions, the service life of houses and buildings is also different. In areas where the natural environment is relatively harsh, due to the impact of natural disasters such as earthquakes and some wind and rain corrosion, the service life of house buildings is very short. Once there is a problem with the building structure of the house, there will be associated side effects, and other places will also be affected to varying degrees, affecting the normal use of the house and threatening people's lives and property safety. In general, under such circumstances, repairing a house will cost a lot of money, and the repair results obtained are not very satisfactory, greatly reducing the overall robustness of the building. Adopt scientific strengthening technology to improve the overall stability of the house structure and improve the safety and stability of the building. Greatly improve the service life of the house building, improve the house's ability to respond to risks, save house maintenance and management costs, and achieve rapid development and progress in the construction industry.

New scientific strengthening technology: carbon fiber strengthening

• Easy installation

• Corrosion resistance

• Short construction period

• No maintenance required

• Light weight, no influence to original structure

• Low cost, cost effective compared with other methods