Structural Health Monitoring

Buildings, bridges, retaining walls, wind turbines, and towers are susceptible to damage from extreme loads such as wind and wind-borne debris, floods, fires, earthquakes, undermining from adjacent construction, landslides, and overloading with heavy contents. Moreover, those same structures can suffer long-term damage if their strength is allowed to deteriorate gradually over time. Examples of such deterioration include metal corrosion, wood decay, concrete attack by adverse chemicals, or cumulative damage from fatigue, foundation settlement, slope creep, or vibrations from adjacent construction. Repair of damage is very costly. Structural Health Monitoring (SHM) can mitigate high repair costs by detecting and measuring damaging phenomena as they occur. Likewise, Structural Health Monitoring can mitigate long-term damage by continuously monitoring the structural condition of key components. Structural Health Monitoring is particularly valuable after there has been a damaging event, if there are concerns about the remaining stability of a structure.

Services

Exponent engineers provide a variety of services that can be tailored to specific applications and requirements. We provide system design, installation, monitoring, and analysis of data for a variety of applications, such as:

  • Monitoring vibration levels experienced by structures adjacent to construction sites and other vibration sources.
  • Investigation and detection of abnormal excitation caused by activities on neighboring sites or other areas of a building.
    • For example, measure vibrations caused by manufacturing processes at a neighboring site, or measure vibrations caused by a dance studio on another floor.
  • Monitoring the stability of a structure after a damaging event
  • Monitor the actual response of structures to wind loads and seismic loads, and compare to the predicted behavior.
  • Monitoring the performance of structures over a long period of time.

Exponent has developed wireless data acquisition systems that can be immediately deployed. These systems can be installed on bridges, buildings, retaining walls, wind turbines, towers, and other structures and monitored in real time.

More importantly, Exponent has the expertise to provide meaningful analysis that enables confident decisions about structural health and to work with clients to establish proper thresholds for triggering and notification.

System Architecture

For Structural Health Monitoring projects, Exponent consultants utilize a modular data acquisition system that can be adapted to the project’s specific needs. The system uses NI-DAQmx modules to perform analog to digital conversion, which means that nearly all types of sensors can be used with the system. Signals can be sent via wired or wireless connection based on the project requirements. The data is then collected and processed on a Windows laptop. Remote data access is provided by a 3G/4G data card installed on the laptop.

This system is ideal for projects that require distributed data acquisition. The system is portable and can be powered by a variety of power sources. The system can be installed using cables up to 300 ft and open areas with up to one mile line of sight using a high-gain wireless antenna.

Exponent stocks various types of sensors including accelerometers, geophones, tiltmeters, string potentiometers, thermometers, pressure sensors, microphones, video cameras, and others. Individual specialty sensors can be purchased and integrated into the data acquisition system.

 

Professionals