Inspection technology and application of highway bridges?

The detection technology and application of highway bridges is very important to understand the realization of the technology in order to better solve the actual problem, each detail is very critical. Zhongda consulting on the detection of highway bridges and application of technology and explain to you.

With the rapid development of the economy, the construction of domestic highway bridges has also continued to progress, the existing bridge structure is increasing, so that the domestic transportation situation has improved to a large extent. However, the weight loaded on highway bridges has been increasing in recent years, resulting in increasing pavement damage on most of the bridges in use, and quality problems, such as reduced capacity, insufficient bearing capacity, and damage to structural members, have been occurring continuously. According to the results of the investigation of the causes of damage to domestic bridges, the main factors causing damage to bridges have three aspects: (1) the early bridge design theory is more conservative and not comprehensive enough, resulting in the bridge design program and the actual construction situation is inconsistent with the design bias, design deficiencies are difficult to ensure the quality of construction of highway bridges; (2) the early bridge deck design is not wide enough, the bridge deck of the Load standard is low, the quality of the bridge decreases under the influence of environmental factors and natural factors, such as humidity changes, temperature changes, wind, rain, floods and freezing, etc., and the structure and performance of the bridge are also changed due to the impact, earthquake and overloaded operation and other major losses; (3) the construction of domestic highway bridges develops too fast, which makes a large number of complex bridges emerge in the city, for example, overpass girders, viaducts, and elevated bridges. Overpass girders, elevated bridges and large-span bridges, etc., however, the bridge construction quality and design technology has not yet matured, resulting in the construction of highway bridges in the construction and use of new accidents; therefore, the bridge

inspection technology for the bridge construction business is of great significance. China's highway and bridge technology has been greatly developed, and can compete with the world's highway and bridge technology, but in terms of the current rate of economic development, is still unable to meet the increasingly severe transportation needs. Therefore, in the future development of the transportation system should

The focus should be on the research of highway bridge inspection technology, to further promote the technological innovation in bridge construction, and strengthen the daily maintenance work. In order to ensure the quality of highway bridge construction and safe operation of bridges, the testing technology of highway bridges is particularly important. From the scientific significance of highway bridge testing and inspection, the reasons for testing, technology and application, to discuss the detection technology and application of highway bridges.

One, infrared thermography and radar detection technology

In the bridge quality testing in the use of ultraviolet wave, infrared thermography and radar and other detection technology, a day can be dozens of bridges or thousands of kilometers of bridge deck or road surface for accurate measurements. Infrared thermography uses an infrared camera to obtain a temperature map of the bridge. The higher temperatures (hot spots) are due to the fact that the concrete in the hot spots rises faster than the rest of the bridge because the bridge is so thin that it appears to be

an insulator filled with air. Radar detects targets by means of electromagnetic waves. Its working principle is to want to the target of the electromagnetic pulse, so that the electromagnetic pulse emitted into electromagnetic waves and reflected back from the heterogeneous interface of the concrete, forming an echo. The echo has a close relationship to the concrete, and its alternating waveforms can detect damage and cracks in the concrete. The combined use of infrared thermal imaging camera and radar can effectively detect most of the existing types of disease in highway bridges.

Two, fiber-optic sensor detection technology

At this stage, the fiber-optic sensor application range is quite wide, can be all over the world, this detection technology involves the detection of physical quantities of more than 100 kinds of detection types, common radiation, level, hydroacoustic, magnetic field, voltage, current, electric field, displacement, vibration, pressure, and temperature and other physical quantities. The working principle of the sensor used for bridge quality inspection is that the Brillouin-scattered light at the strain position of the optical fiber will change accordingly after being subjected to tensile and compressive influences. By observing the frequency, the amount of strain in the axial direction of the fiber is proportional to the Brillouin scattering frequency shift. The deformation of the bridge is further calculated by measuring the Brillouin scattering frequency shift and the temperature of the optical fiber. According to the measurement of "optical loss", the deformation of the bridge can be calculated in detail, and the calculation result can be accurate to 0.02mm, and the transmission time of the optical pulse reflection can clarify the specific location of the bridge deformation, and the error size is within 0.75m. Combining these two methods in bridge inspection can understand the deformation size and deformation location distribution details of the bridge within a certain length. Fiber optic sensors in a narrow range can still achieve the effect of measurement

Therefore, during the construction of the sensor can be buried in the bridge, through the two ends of the receiving instrument can play a long-term monitoring of the bridge quality of the effect.

Three, radio detection technology

The U.S. Federal Highway Administration has been for the detection of fatigue damage to steel bridges and the development of bridge detection equipment, the main principle of the detection equipment that leads to cracks in steel bridge components is due to the bridge is subjected to long-term with cyclical characteristics of the load. The expansion of the cracks in the bridge structure is subtle, while the expansion of the bridge structure surface will be with the release of energy for the generation of stress waves. Radio detection technology can determine the number of stress waves and their exact location. In addition, the U.S. Federal Highway Administration has also developed other detection technology, namely acoustic emission detection technology, this technology was commonly used to detect the construction quality of the mine pressure, and now its detection range and popularized to other industries, such as elevated bridges, dams, chemical containers, shipbuilding, aircraft and other industries. At this stage, acoustic emission bridge inspection equipment has been produced and successfully applied in the inspection of existing bridges. The acoustic emission type of detection equipment can understand the internal condition of each material of the bridge, such as crack distribution, crack development, etc. Through the understanding of the internal condition of the material, the construction technology of the bridge can be studied in depth, so as to predict the service life of the bridge. The principle of acoustic emission monitoring equipment is to grasp the longitudinal wave propagation speed as well as the propagation direction of the sound wave inside all kinds of materials, and then combine the time difference between the longitudinal wave and the contact of each sensor to judge the location of defects inside the material. Wavelet analysis refers to the analysis of small waveforms, commonly used to analyze the bridge structure as well as pile foundation test results.

Four, induction detection technology

Induction detection technology has a wide range of applications, for the detection of physical quantities in the bridge and the development of a variety of sensors. For example, accelerometers, mainly used to measure the bridge due to the stress wave caused by the fracture of steel; small sensing device, can be buried in the bridge beams inside, the main measurements of corrosion of reinforcing steel and concrete chloride content, electrical conductivity; displacement sensors, mainly used for the displacement of the bridge wing wall. These types of equipment has a simple structure, stable performance, low price and so on, can be used in a variety of bridges under construction and in use in a large number of bridges.

Fifth, other bridge inspection technology

1, laser system

The technology makes the use of laser systems to measure the three-dimensional coordinates of the target for immediate measurement. The system can play a good measuring effect in the measurement of wood, concrete and general steel. The laser system can quickly and accurately measure the part of the bridge that has been deformed by the passage of a vehicle, and with the help of a long period of time, the coordinate data can be compared and analyzed, so as to determine whether the bridge has been damaged by pre-stressing or settling.

2, new sensors

Domestic and foreign sensors have been developed a variety of sensors, such as fiber optic grating problem sensors, three-way accelerometer, magnetic flux sensors and ultrasonic three-way anemometer and so on. Accompanied by a large number of early construction of domestic bridges are stepping into the period of disease outbreak, highlighting the bridge inspection workload, single function of the inspection equipment, inspection equipment is expensive and imperfect equipment and other issues. Compared with foreign bridge inspection technology, domestic inspection technology is still many deficiencies, can be a lot of room for progress, the domestic bridge inspection technology to achieve informationization, intelligence and automation must be long-term efforts to develop.

3, intelligent bearing

Intelligent bearing internal optical fiber sensors, mainly used to measure the bridge shear force and compressive strain. The measurement equipment can be preset in the internal optical fiber sensor on the bridge constant load and live load distribution for the collection, for the bridge to provide a basis for the judgment of the technical condition of the bridge.

Concluding Remarks:

At this stage, the construction quality and bearing capacity of highway bridges required by the development of society are constantly rising. Highway infrastructure has entered a new period of development with the rapid development of social and economic development at this stage, the rapid development of highway and bridge engineering, highway traffic pressure is also increasing, many of the existing bridges and their carrying capacity can not keep up with the reality of the development of social speed. Bridge construction companies need to continue to study the updated bridge inspection technology, with the help of continuous optimization of the inspection technology, found in the use of the existing bridge problems, early grasp of the bridge to deal with the disease, so as to maintain the quality of the bridge, to maintain the normal operation of the traffic.

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