一、 Background of the Application of Bridge Structure Safety and Health Monitoring System

As an important carrier of public transportation, bridge plays a vital role in the smooth operation of regional traffic and social and economic development. With the rapid development of social economy, bridge traffic flow increases rapidly, and the impact of bridge safety hazards is intensified.Bridges are damaged and damaged due to factors such as harsh operating environments, load effects, and long service life, which pose a threat to bridge safety and cause bridge accidents. In recent years, bridge safety accidents have occurred frequently, with significant social impact and serious consequences for people's lives and safety.According to the "Opinions on Further Improving the Safety and Durability Level of Highway Bridges" issued by the Ministry of Transport, document Jiao Gao Dao Fa [2020] No. 127 stipulates that "by the end of 2025, the health monitoring system for special bridge structures such as crossing rivers, seas, and canyons should be fully covered. By 2035, the construction, maintenance, and management level of highway bridges should enter the forefront of the world." In order to achieve the knowability and measurability of the lifeline status of bridges at all stages, timely understand and grasp the health dynamics and safety status of bridges, verify design theories, and guide the design of similar bridges in the future, it is particularly important to establish a scientific health and safety monitoring system for their operation period.

二、 Bridge type and monitoring location

1. The safety and health inspection of cable-stayed bridges mainly includes weighing monitoring, expansion joint displacement monitoring, stress monitoring, settlement monitoring, external environmental monitoring, vibration monitoring, cable force monitoring, spatial displacement monitoring, etc.

2. The safety and health inspection of suspension bridges (also known as suspension bridges) mainly includes: full bridge GNSS positioning, suspension cable force monitoring, expansion joint displacement monitoring, stress monitoring, vibration monitoring, main cable fastening force monitoring, external vehicle load monitoring, external environmental monitoring, external abnormal warning, etc.

3. The safety and health inspection of beam bridges mainly includes: GNSS positioning of the entire bridge, displacement monitoring of expansion joints, stress monitoring, vibration monitoring, tilt monitoring of bridge piers, monitoring of external vehicle load capacity, and external environmental monitoring.

4. The safety and health inspection of arch bridges mainly includes: full bridge GNSS positioning, expansion joint displacement monitoring, stress monitoring, vibration monitoring, arch ring convergence monitoring, external vehicle load monitoring, and bridge pier inclination monitoring.

三、 The significance of vibration monitoring in monitoring safety and health data of bridge structures

The dynamic characteristic parameters (frequency, mode shape, and damping) and vibration level (strength and amplitude) of a bridge are indicators of the overall safety of the bridge. The degradation of the strength of bridge materials can cause changes in the structural vibration characteristics, such as a decrease in the stiffness of the bridge structure, which can lead to a decrease in the natural frequency of the bridge. Changes in the local mode shape of the bridge may indicate local damage to the structure. Therefore, monitoring the dynamic characteristics and vibration levels of bridges can achieve the overall goal of monitoring the health status of bridge structures.

四、 Application of Senther Technology in Bridge Vibration Monitoring

Recommended 374A Seismic Sensor Product Overview:        

The 374A series accelerometer is a specially designed accelerometer for detecting ultra-low frequency and low-frequency vibrations in large buildings, infrastructure, and earthquake detection applications; Its characteristic is to output a low-noise and high amplitude signal through a sensing mechanism, with excellent measurement resolution. Both ceramic crystals and quartz crystals can be used in the design of seismic acceleration sensors, with ceramic crystals having higher output efficiency than quartz crystals.The 374A product uses ceramic crystals as sensitive components, which provides better signal quality and low-frequency response characteristics. It also has a built-in low-noise signal modulator, resulting in high resolution. In order to achieve the best measurement results, seismic acceleration sensors are usually used together with gain amplifiers and power signal modulators. This accelerometer adopts laser welding to firmly weld the stainless steel shell and military type joint together; The shell isolation, internal shielding, external environment (including RF, EMI, ESD, and overload), and the impact of misoperation on the product are completely controllable, ensuring excellent repeatability and long-term stability of the product.

Characteristics of 374A seismic sensor:

·Ultra-low frequency response

·Top out connector

·High sensitivity

·Metal welding seal

·Shell isolation

·EMI/RFI shielding

Application of 374A seismic sensor:

·Building vibration monitoring

·Earthquake detection

·Bridge monitoring

·Research on Infrastructure Vibration

·Structural testing