Acoustic Emission Monitoring for Detecting Cracks in Steel Bridges

The safety and longevity of steel bridges are vital for transportation infrastructure. Continuous exposure to traffic-induced vibrations, thermal fluctuations, and environmental stresses can lead to structural degradation over time. Acoustic Emission Monitoring (AEM) provides a real-time, advanced approach to detecting and tracking crack propagation in steel bridges, enabling early maintenance and extending service life.

Æmission Digitizer/Recorder: The Core of Our AEM System

At the heart of our monitoring solution is Æmission, a state-of-the-art acoustic emission monitoring system designed for high-speed data acquisition and real-time signal processing.

  • High-Speed Data Acquisition: Operates at 1.25 MSps @ 18-bit resolution or 5 MSps @ 16-bit resolution, ensuring high-fidelity signal capture.
  • Patented FPGA Algorithms: Developed in collaboration with the Polytechnic University of Turin, enabling onboard processing of acoustic emission waves.
  • Localized Data Processing: Extracts key crack progression indicators, such as βt, b-value, and cumulative count, facilitating predictive maintenance strategies.
  • Proven Performance: Validated through the MONFRON project, a large-scale experimental initiative funded by Regione Toscana in Italy.

Acoustic Emission (AE) Technology for Structural Health Monitoring

Acoustic emission (AE) is the release of stress waves within a material caused by internal structural changes or external mechanical loads. These waves propagate through the material and can be detected to assess its condition, revealing cracks or other forms of damage.

AE testing is a non-destructive technique used to identify and monitor crack development in structures, including metals, concrete, and composites. When subjected to mechanical stress, temperature variations, or environmental changes, a structure generates acoustic emissions that sensors capture on its surface.

The recorded signals are processed using advanced software and hardware to pinpoint the AE source and locate potential damage. Continuous monitoring allows engineers to track crack progression, evaluate structural integrity, and make data-driven decisions regarding maintenance, repairs, or replacements. AE testing is a crucial tool for ensuring the safety and longevity of critical structures across industries such as aerospace, civil engineering, and manufacturing.

Application of AEM in Steel Bridges

Steel bridges experience constant mechanical and environmental stress, making them susceptible to fatigue cracks and localized failures. Implementing an AEM system on existing steel bridges provides real-time insights into structural integrity and ensures early intervention before catastrophic failures occur.

Use Cases:

  • Traffic-Induced Vibrations: AE sensors monitor crack initiation and progression in high-stress zones such as welds and riveted connections.
  • Thermal Fluctuations: Seasonal temperature changes cause expansion and contraction, exacerbating material fatigue.
  • Corrosion Monitoring: Detects stress-corrosion cracking, an insidious form of material degradation.
  • Emergency Event Detection: Sudden impacts (e.g., vehicle collisions, seismic activity) introduce immediate damage, with AE-based monitoring aiding rapid response.
  • Predictive Maintenance Planning: Engineers analyze AE data trends to forecast maintenance needs, minimizing costs and avoiding unscheduled repairs.

Æmission System Architecture

Æmission is supplied with eight piezoceramic sensors, selected and characterized with assistance from the Polytechnic University of Turin for optimal civil structure monitoring. These sensors are strategically placed around the monitored area and connected via 10-meter cables.

Key Features:

  • Analog Signal Processing: The analog signals from the piezoceramic sensors are conditioned and level-adapted by a cascade of analog filters before digital conversion.
  • High-Speed Data Conversion: Eight high-speed ADCs (1.25MSps@18bit or 5MSps@16bit) continuously convert analog signals into digital format, synchronized to the same clock source.
  • Parallel Processing with FPGA: Digital signals are acquired and processed in parallel by the FPGA, with only relevant events transferred to the Linux CPU.
  • Data Storage & Remote Sharing: Events are stored locally within the Linux CPU and can be shared remotely via WiFi or 3.5G connection.
  • Integrated GNSS Receiver: Synchronizes multiple Æmission units, enabling scalable monitoring across extensive infrastructures.
  • Comprehensive Data Analysis: After sufficient monitoring, parameter plots help analyze cracking patterns and structural health trends.

Real-World Monitoring Example

The following graphs represent an ongoing acoustic emission survey in a marble quarry:

  • AE Cumulative Count
  • AE/hour Trends
  • Event Frequency Distribution
  • Amplitude Variations
  • βt and b-value Progression
  • 3D Localization of Emission Sources

In the 3D representation, blue squares denote AE sensors, while red dots indicate the localization of emission sources.

Implementation Plan

Our proposal outlines a comprehensive approach to designing, installing, and maintaining an AEM system for steel bridges:

  1. Site Assessment & Sensor Placement: Identify high-risk zones and strategically install AE sensors.
  2. Real-Time Data Collection & Processing: Utilize the Æmission digitizer/recorder for continuous monitoring.
  3. Data Interpretation & Reporting: Implement advanced algorithms to analyze AE parameters and generate actionable insights.
  4. Predictive Maintenance & Intervention: Leverage AEM data to schedule repairs before structural failure occurs.

Why QuakeLogic’s AE Monitoring System?

QuakeLogic’s AE monitoring system is a cutting-edge solution for steel bridge health assessment. Our system is designed for high-performance data acquisition, real-time crack detection, and predictive maintenance planning. By investing in our AE monitoring technology, bridge owners and engineers can ensure structural safety, extend service life, and reduce maintenance costs.

Buy Our AE System Today!

Visit our website to explore our state-of-the-art acoustic emission monitoring hardware and equip your infrastructure with the latest technology for proactive maintenance.

BUY ACOUSTIC EMISSION SYSTEM NOW!

About QuakeLogic

QuakeLogic is a global leader in monitoring solutions, offering innovative technologies for accurate seismic data acquisition and analysis. Our solutions empower organizations worldwide to predict, understand, and mitigate risks effectively.

For more information or inquiries, reach out to our sales team today!

Ensuring Effective Vibration Isolation for Shake Table Experiments

Shake tables are powerful tools for simulating earthquakes, studying structural dynamics, and testing critical infrastructure components. However, operating a shake table inside a building presents a unique challenge: how to isolate vibrations effectively to prevent any impact on the surrounding structure.

In this blog, we’ll explore the importance of vibration isolation, the role of an inertia mass block, and the key considerations for achieving precision and stability during shake table experiments.

Why Vibration Isolation Matters for Shake Tables

Shake tables generate high dynamic forces and vibrations during testing. If not properly isolated, these vibrations can:

  • Transmit through the building’s foundation.
  • Cause damage or wear to surrounding infrastructure.
  • Create feedback vibrations, reducing experimental accuracy.
  • Compromise the safety of personnel and equipment.

The Challenge of Isolation: Precision vs. Power

Shake tables must simulate real-world earthquake scenarios with precision while ensuring vibrations remain fully decoupled from the building’s structural slab. Achieving this balance requires a carefully engineered vibration isolation system.

The Role of an Inertia Mass Block in Vibration Isolation

One of the most effective ways to isolate a shake table is by placing it on an inertia mass block. This intermediate concrete foundation acts as a dynamic buffer between the shake table and the building slab.

Key Benefits of an Inertia Mass Block:

  1. Increased Stability: Prevents rocking and tilting during high-amplitude experiments.
  2. Energy Dissipation: Absorbs and dampens dynamic forces generated by the shake table.
  3. Load Distribution: Spreads the shake table’s weight evenly across air springs.
  4. Reduced Resonance Effects: Lowers the natural frequency of the system, minimizing unwanted vibrations.
  5. Long-Term Durability: Reduces fatigue on isolation components, ensuring reliable performance over time.

Without an inertia mass block, air springs may experience uneven loading, excessive deflection, or reduced isolation efficiency.

Air Springs: Fine-Tuning Vibration Isolation

Underneath the inertia mass block, air springs play a critical role in vibration isolation. These components are designed to:

  • Absorb vibrations across a wide frequency range.
  • Provide adjustable stiffness and damping characteristics.
  • Maintain stability under varying loads.

Key Considerations for Air Springs:

  • Load Capacity: Each air spring must support a specific portion of the total system weight.
  • Stiffness: Proper stiffness tuning ensures a natural frequency below 2 Hz for effective isolation.
  • Static Deflection: Optimal deflection ensures air springs operate within their designed range without excessive compression.

When combined with an inertia mass block, air springs deliver precision and reliability, keeping vibrations isolated and the surrounding building safe.

Designing an Optimal Vibration Isolation System

Step 1: Build a Stable Inertia Mass Block

  • Construct a concrete block, typically 2 to 3 times the weight of the shake table.
  • Ensure a minimum 5 cm isolation gap around the block.

Step 2: Use Proper Air Springs

  • Select air springs capable of supporting the total system weight (shake table + inertia mass block).
  • Ensure the natural frequency remains below 2 Hz.

Step 3: Isolate Utility Connections

  • Use flexible hoses and conduits for hydraulic, pneumatic, and electrical connections to avoid creating vibration pathways.

Step 4: Monitor and Fine-Tune the System

  • Install vibration sensors to monitor performance.
  • Adjust air pressure in the springs to maintain optimal isolation.

What Happens Without Proper Isolation?

Neglecting proper isolation can lead to:

  • Vibrations transmitting through the building slab, causing unintended structural stress.
  • Inaccurate experimental results due to feedback vibrations.
  • Excessive wear and reduced lifespan of the shake table and air springs.

In severe cases, it can even invalidate test results, rendering experiments ineffective.

Key Takeaways for Shake Table Vibration Isolation

  1. Inertia Mass Block: Provides stability, uniform load distribution, and energy absorption.
  2. Air Springs: Fine-tune vibration isolation and ensure dynamic forces are not transmitted to the building.
  3. Isolation Gap: Prevents secondary vibration paths.
  4. System Monitoring: Real-time monitoring ensures ongoing performance and reliability.

When properly designed, these components work together to create a robust vibration isolation system that protects both the experiment and the surrounding environment.

Consult QuakeLogic:

At QuakeLogic, our solutions ensure accurate, repeatable experiments while maintaining complete structural safety.

Interested in designing an isolation system for your shake table project?
Reach out to us today at sales@quakelogic.net, and let’s build a solution tailored to your needs.

Because in vibration isolation, precision isn’t optional—it’s essential.

MASW and ReMi: Unlocking Subsurface Insights with DoReMi Seismograph

In the realm of geophysical exploration, two advanced seismic techniques—MASW (Multi-Channel Analysis of Surface Waves) and ReMi (Refraction Microtremor)—are leading tools for mapping shallow shear-wave velocity (Vs) profiles. These methods provide critical data for applications ranging from seismic hazard assessments to infrastructure development and resource exploration. With the DoReMi Seismograph, professionals gain access to a powerful, modular, and precision-driven solution, complete with free analysis software for seamless operation in diverse environments.

What is MASW (Multi-Channel Analysis of Surface Waves)?

MASW is an active-source seismic technique that analyzes surface waves generated by an external source, such as a sledgehammer, weight drop, or vibroseis truck. The energy produced by these sources travels along the ground surface as Rayleigh waves, and MASW records their dispersion characteristics to calculate shear-wave velocity (Vs) at different depths.

Key Highlights of MASW:

  • Source Type: Active (sledgehammer, weight drop, vibroseis)
  • Depth Penetration: Depends on array length, sensor frequency, and energy source
  • Applications:
    • Seismic hazard assessment
    • Subsurface characterization
    • Soil stiffness evaluation
    • Infrastructure foundation studies

MASW excels in environments where controlled energy sources can be applied, offering reliable data even in noisy urban settings.

What is ReMi (Refraction Microtremor)?

ReMi is a passive-source seismic technique that relies on ambient noise or microtremors generated naturally by environmental activities, such as traffic, wind, or machinery. Unlike MASW, ReMi doesn’t require an active energy source, making it ideal for sites where active sources cannot be used.

Key Highlights of ReMi:

  • Source Type: Passive (environmental noise, microtremors)
  • Depth Penetration: Primarily depends on array length and sensor frequency
  • Applications:
    • Deep subsurface profiling
    • Seismic hazard mapping
    • Geological fault studies
    • Urban development site assessments

ReMi surveys are particularly advantageous in environments with high background noise levels.

How Do MASW and ReMi Differ?

FeatureMASWReMi
SourceActive (artificial source)Passive (ambient noise)
Depth PenetrationShallow to moderate depthDeeper depths
Data QualityControlled, higher resolutionNatural, dependent on ambient noise
Best Used ForUrban projects, shallow investigationsDeep subsurface studies

While MASW excels in controlled, shallow-depth investigations, ReMi thrives in scenarios where deep subsurface profiling is required.

DoReMi Seismograph: The All-in-One Solution

The DoReMi Seismograph is a cutting-edge, modular digital telemetry system designed for both MASW and ReMi surveys. It combines advanced hardware capabilities with user-friendly software, ensuring high-precision data acquisition in any operational setting.

Key Features of DoReMi Seismograph:

  • Modular Design: Scalable to support 1 to 255 channels, allowing flexible configurations for diverse projects.
  • Embedded Recording Electronics: Electronics are embedded in the cable, reducing electromagnetic interference.
  • Lightweight & Portable: Easily transported with a cable wheeler, ensuring smooth deployment in remote sites.
  • Integrated Battery System: Built-in rechargeable battery ensures continuous and independent operation.
  • Noise Reduction: Digitalization near the geophone minimizes noise and prevents data loss or crosstalk.
  • Flexible Sensor Integration: Supports 4.5 Hz geophones, downhole sensors (SS-BH-5C), and other seismic equipment.
  • Free Analysis Software: Compatible with any processing software, simplifying data management and interpretation.

Advanced Software for Seamless Operation

The DoReMi Seismograph is complemented by advanced software tools, designed to streamline on-site data quality checks and post-processing workflows.

Key Software Capabilities:

  • Pre-Shot Noise Monitoring: Ensures data integrity before acquisition.
  • Downhole & Surface Data Management: Simplifies different acquisition scenarios.
  • Signal Inversion & Overlapping: For SH shots and advanced processing.
  • Data Filtering & Spectral Analysis: Advanced tools for FK and FV analysis.
  • Roll-Along Acquisition: Simplifies large-area surveys.
  • HVSR Preview: Horizontal-to-Vertical Spectral Ratio preview for subsurface mapping.
  • Multi-Language Support: Available in English, Italian, and Chinese.

Applications of DoReMi Seismograph

  • Seismic Hazard Assessment: Earthquake resilience site characterization.
  • Geophysical Exploration: MASW, ReMi, Refraction, Reflection, and Downhole surveys.
  • Infrastructure Projects: Foundation analysis and underground mapping.
  • Resource Exploration: Aquifer detection, oil and gas reservoir profiling.
  • Urban Development: Roadbed evaluations and soil stiffness assessments.

Data Outputs from DoReMi Seismograph

  1. 1D Shear Wave Velocity Profile:
    • Vertical shear-wave velocity analysis for site characterization.
  2. 2D Shear Wave Velocity Profile:
    • Comprehensive subsurface mapping when multiple acquisitions are performed.

These outputs are essential for geotechnical engineers, seismologists, and urban planners in making informed decisions.

Why Choose DoReMi Seismograph for MASW and ReMi Surveys?

  • Dual Capability: Seamlessly supports both MASW and ReMi techniques.
  • High Precision: Noise-free, reliable data acquisition.
  • Scalable Design: Flexible configurations from 1 to 255 channels.
  • Advanced Software Integration: Simplified analysis and data management.
  • Portability: Lightweight design with modular architecture.
  • Expert Support: Dedicated training, support, and consultation from QuakeLogic.
👉 Order Your DOREMI Equipment Now

Conclusion

The DoReMi Seismograph by QuakeLogic represents a state-of-the-art solution for MASW and ReMi seismic surveys, offering unmatched flexibility, precision, and reliability. Whether it’s mapping shallow shear-wave velocity using MASW or profiling deeper subsurface layers with ReMi, DoReMi delivers results you can trust.

Experience precision, reliability, and innovation with the DoReMi Seismograph—your trusted partner in seismic exploration.

📞 For more information or to request a demo, contact us at:
Phone: +1-916-899-0391
Email: sales@quakelogic.net
Website: www.quakelogic.net

Discover seismic monitoring excellence with QuakeLogic’s DoReMi Seismograph!