MISTRAS has been providing bridge monitoring and testing solutions since 1972, partnering with DOTS, FHWA, Engineering Firms and Universities to provide the right NDT solution for your application.
For over 30 years, MISTRAS has been aware of the rising demand to ensure structural integrity of bridges. Since bridges usually require more than the typical visual inspection, the additional information obtained from our monitoring solutions can provide input to authorities, and assist in making informed and effective decisions with regard to planning for maintenance, repair, rehabilitation or replacement. In addition, On-line Monitoring and Sensor Fusion can cover failure mechanisms, including unpredictable deterioration.
Hands-on inspection of suspension bridge cables is a costly (several millions of dollars) and time consuming process, requiring removal of the wrapping wire, paste and wedging of the cable. However, this inspection process only allows for approximately 2-3% of the wires to be inspected; counting the number of broken and corroded wires and then using statistical analysis to estimate the total number of corroded and broken wires within the panel to assist in the determination of the remaining cable strength. MISTRAS’ solution is a Structural Health Monitoring (SHM) system that uses Acoustic Emission (AE) for the detection of wire breaks. MISTRAS SHM systems monitor the cable 24 hours a day 7 days a week with real-time data processing, analysis, location and alarming, and can provide bridge engineers and owners with the information they need for informed decisions and better resource management of funds, personnel, maintenance, repair or rehabilitation.
Cable Tendons are a critical component of bridges and inspection of these cables is a costly and time consuming process. Improper grouting, sheathing, overstress during construction, weather induced vibration, corrosion and fatigue are just a few issues that have lead to wire breaks and subsequent failure of the tendon in new and relatively young cable stays. Our solution is installing an Acoustic Emission Structural Health Monitoring (SHM) system during installation or after the tendons have been installed for detection of potential wire breaks. Our SHM systems monitor the cable 24 hours a day, 365 days a year with real-time data processing, analysis, location and alarming and can provide bridge engineers and owners with the information they need for informed decisions and better resource management of funds, personnel, maintenance, repair or rehabilitation.
MISTRAS systems have been on suspension and cable stay bridges for over 10 years. In 1972, we performed our first bridge cable test on a bridge in California, where cables on the lift-span were tested for fitness for service. Since then we have installed AE systems on suspension bridges in Philadelphia, New York City, Virginia, England and other parts of the world to monitor, record, interpret, identify and report wire breaks and other activities. In addition, we can also perform remote diagnostic checks, maintenance and remote-calibration to maintain the operation and performance of the systems.
Acoustic Emission is used extensively to detect, locate and quantify cracking in steel bridges. Experience gained in the lab and over 30 years of testing oil and gas steel structures assist us in the routine application of assessing steel bridge structures both globally and in local locations to check for the presence of steel cracking. Tested and approved by FHWA and other international agencies on defects identified by inspection and on subsequent repairs, AE is a power tool for bridge inspectors. MISTRAS also has hundreds of experts in x-ray, magnetic particle and other traditional NDT technologies.
MISTRAS has used Acoustic Emission, Ground Penetrating Radar, Impact Echo and other technologies to assess concrete. AE can detect tendon breaks in concrete beams, cracking caused by rebar corrosion and fretting from crack surfaces, and is still being used in research to hear if concrete has matured.
It doesn’t take explosives to bring an aging bridge to failure. In 2006, a main tendon on a cable stay bridge was nearly severed. The problem was detected before it became critical but only after $2 million in damages had already been incurred. The bridge was instrumented with our proven system and provides alarms to authorities, in real-time, if various acts of vandalism are in progress. Bridges, dams and other structures can be monitored with single or multiple sensor technologies to detect problems before they happen.