Bridge Structural Health Monitoring

In November 2025, part of the 758-metre Hongqi Bridge in Sichuan, China, collapsed just months after opening to traffic. Fortunately, the bridge had been closed the day before, and no casualties were reported – but the incident raises a critical question: how safe are our modern bridge and viaduct structures, really? This incident is a clear reminder that bridge structural health monitoring is essential if we want to understand how our critical assets behave over time, not only at the moment of failure.Reuters+1

1. What Happened at the Hongqi Bridge?

The Hongqi Bridge in Maerkang, Sichuan Province, was designed as a flagship infrastructure project on China National Highway 317, connecting Sichuan with Tibet across steep mountainous terrain. The bridge is about 758 metres long, with piers up to 172 metres high, carrying a two-lane road across a deep canyon near the Shuangjiangkou hydropower project. Vikipedi+1

Key facts:

• Construction was completed in early 2025, and the bridge opened to traffic in April 2025. Vikipedi+1
• On 10 November 2025, local authorities noticed cracks in nearby slopes and roads, and signs of terrain deformation on the mountainside. The bridge was closed to traffic as a precaution. Reuters+1
• On 11 November 2025, a landslide on the right-bank slope triggered the collapse of the western approach and roadbed. The main central spans largely remained standing, while the approach section failed dramatically – an event captured in widely shared video footage. The Washington Post+2Sky News+2
• Thanks to the prior closure, no casualties were reported. Guardian+1

Initial official statements pointed to the landslide as the primary cause of the collapse. At the same time, engineers and the public have raised broader concerns about geological risk, slope management, and potential design or construction deficiencies in such complex terrain. Vikipedi+2eos.org+2

2. How Can a Brand-New Bridge Become So Risky So Quickly?

From a public perception standpoint, the instinctive question is:

“How can a bridge that opened just months ago partially collapse already?”

From an engineering perspective, the picture is more nuanced – and very instructive.

2.1 Geotechnical risk can outweigh superstructure quality

Even if the superstructure is built with high-quality materials and state-of-the-art design, the weakest link is often the ground:

• steep slopes and landslide-prone geology,
• changing groundwater conditions,
• large-scale hydraulic projects (like nearby reservoirs) altering the stress state,
• heavy rainfall events and long-term weathering. eos.org+1

The Hongqi case illustrates that a “perfect” bridge on an unstable slope is still a high-risk system.

2.2 Warning signs existed – but late in the process

The good news: visible cracks and terrain shifts were detected, and authorities closed the bridge in time. This is a successful example of emergency risk management.

The more strategic question is:

Could we have seen these signals earlier, in a more quantitative way, before visible damage and dramatic slope movement?

That’s precisely where continuous monitoring makes the difference between reactive and proactive safety.

2.3 Structures are not static; they live in a changing environment

Design codes and calculations are essential, but they are just the starting point. Once a bridge goes into service, it is exposed to:

• daily and seasonal temperature cycles,
• traffic loading and fatigue,
• earthquakes and aftershocks,
• rainfall, reservoir level changes and groundwater fluctuations,
• long-term soil creep and consolidation.

Without long-term monitoring, we see only snapshots of the bridge’s health – not the full story. Effective bridge structural health monitoring turns these snapshots into a continuous timeline, making it possible to see how the structure and its foundations evolve under real environmental and loading conditions.

This is why bridge structural health monitoring (SHM) is moving from “nice to have” to core safety requirement in complex environments.

3. What Should Structural Health Monitoring for Bridges Include?

The Hongqi Bridge collapse is a powerful reminder of what a minimum SHM package for bridges and viaducts should look like, especially in mountainous or geotechnically complex areas.

3.1 Geotechnical and slope monitoring

It’s not enough to monitor the bridge deck and piers. The approaches, embankments and surrounding slopes must be part of the monitoring strategy:

• Tilt / inclination sensors and in-place inclinometers
  • Detect micro-rad level tilt and rotation in slopes, abutments and retaining structures.
• Displacement and settlement sensors
  • Track long-term settlement in approach fills and abutments.
• Hydrological and environmental sensors
  • Rain gauges, groundwater / pore-pressure sensors and reservoir level data help link water conditions to slope stability.

When these measurements are integrated into a real-time platform with threshold-based alarms, engineers can move from “we saw cracks yesterday” to “we saw the slope trend changing weeks or months ago”.

3.2 Dynamic monitoring of the bridge superstructure

In practice, bridge structural health monitoring combines these acceleration and strain measurements to track changes in stiffness, boundary conditions and overall structural performance.

On the bridge itself, accelerometers and strain sensors are key to understanding structural behaviour:

• MEMS accelerometers at mid-span and on piers
  • Capture vibration data under traffic, wind and earthquakes.
  • Enable operational modal analysis to track changes in natural frequencies, mode shapes and damping.
• Strain gauges and displacement sensors
  • Measure stress and deformation in critical sections, expansion joints and bearings.

Changes in dynamic properties over time can indicate stiffness loss, damage or boundary condition changes, enabling early intervention before visible distress appears.

3.3 Digital twin and early warning logic

Sensor data alone is not enough – it must be connected to a digital twin and robust analytics:

• Numerical models (FE models / digital twins)
  • Provide a baseline for what “normal” behaviour looks like under various loading and environmental conditions.
• Data-driven anomaly detection
  • Uses historical data to detect when the system leaves its “safe operating envelope”.
• Risk-based thresholds and colour-coded alarms
  • Green–yellow–red dashboards for bridge owners and operators, integrating slope, structure and environment into one risk picture.

Applied to a case like Hongqi, a combined indicator (slope tilt + rainfall / reservoir level + settlement trends) could have offered earlier, more quantitative warnings, even before dramatic geometry changes or large cracks appeared.

4. What We at StructHealth Take From the Hongqi Story

At StructHealth, our end-to-end platform for bridges, viaducts and retaining walls is built exactly around these lessons:

• Sensor layer
  • MEMS accelerometers, tilt/angle sensors, displacement and crack sensors, temperature and environmental sensors.
  • Reliable industrial communication via PoE, CAN-bus and other field-proven protocols.
• IoT & communication layer
  • Secure, robust data acquisition from challenging sites to the cloud or on-premise servers.
  • Designed for low data loss and continuous operation in harsh environments.
• Analytics & visualisation layer
  • Web-based dashboards with map views of all monitored assets.
  • Time-series and frequency-domain tools, threshold monitoring and alert rules.
  • Ready-to-use bridge / viaduct monitoring dashboards tailored to infrastructure owners.

For us, the key question is not:

“Is the bridge finished?”

but rather:

“How well do we understand and track this bridge throughout its entire life cycle?”

The goal is not just to “get lucky” and avoid casualties because a structure happened to be closed a day earlier.
The goal is to systematically detect risk build-up, so operators can:

• temporarily close or restrict traffic in advance,
• route traffic through alternatives,
• plan inspections, retrofits or mitigation measures proactively.

5. Conclusion: Continuous SHM Should Be the New Standard for Bridges

The partial collapse of the Hongqi Bridge shows that:

Building an impressive bridge is not enough;
we must equally invest in monitoring the ground, slopes and environmental context that support it.

For:

• mountainous and landslide-prone regions,
• bridges interacting with large reservoirs and hydropower schemes,
• critical logistics and highway corridors,

Bridge structural health monitoring is no longer a luxury – it is a baseline safety requirement.

StructHealth Bridge & Viaduct Monitoring Solutions

In Turkey and the surrounding region, StructHealth provides end-to-end SHM solutions for bridges and viaducts, including:

• sensor selection and engineering design,
• on-site installation and commissioning,
• IoT data acquisition and analytics,
• web-based dashboards and alarm scenarios.

To explore how we can help you monitor your bridge portfolio:

• Learn more about our infrastructure monitoring solutions on our
  Bridge Monitoring Solutions page.
• Or get in touch with us directly via our
  contact page to discuss your specific project or asset.

On 29 October 2025, the sudden collapse of a seven–storey residential building in the Gebze district of Kocaeli, Türkiye, shocked the country. Within seconds, one ordinary apartment block turned into a fatal disaster. A family of five was trapped; tragically, only their 18-year-old daughter was rescued alive from the rubble.AA Agency

This event is a painful reminder that buildings can pose critical risks not only during earthquakes but also in everyday life, even on seemingly “quiet” days.

Subsequent investigations in the surrounding area revealed that many nearby buildings also showed serious structural problems. This is no longer about a single building; it points to a wider, systemic issue in the building stock.

As StructHealth, in this article we explore what we can learn from such incidents and where Structural Health Monitoring (SHM) fits into this bigger picture.

1. Why do “healthy-looking” buildings collapse?

Preliminary assessments and expert comments about the Gebze collapse highlight risk factors that are unfortunately familiar in many regions of Türkiye and beyond.

Ground movements and soil settlements

• Buildings founded on variable soil conditions may experience differential settlements over time.
• Nearby infrastructure works – such as deep excavations, tunnels, metro lines, or changes in the groundwater level – can weaken the soil supporting the structure.
• These settlements can create progressive damage, especially in corner columns and critical load-bearing elements, where stress concentrations and shear forces increase slowly but steadily.

Soft-storey effects and commercial use at ground level

• Ground floors used as shops, markets, cafés or restaurants often have fewer partition walls and larger open spans.
• This can create a soft-storey mechanism: the ground floor becomes significantly weaker and more flexible than the floors above.
• In both earthquakes and settlement scenarios, this soft storey tends to behave like the weakest link in the chain, making the entire building more vulnerable to collapse.

Historical use and thermal effects

• In some buildings, the ground floor may previously have been used as a restaurant or similar high-temperature environment.
• Prolonged exposure to heat can degrade concrete microstructure, reduce the bond between reinforcement and concrete, and weaken critical columns and beams.
• Even if visual signs are limited, the structural capacity may already be compromised.

Ageing, poor maintenance and ignored warning signs

• Cracks, excessive deflections, spalling at beam-column joints, as well as doors and windows that begin to jam, are often normalised as “old building behaviour”.
• In reality, these are key indicators that should be monitored throughout the service life of the structure.
• When such symptoms are ignored, damage can accumulate over years until a relatively small trigger leads to a disproportionate collapse.

Bottom line: Even if a building has an approved design, permit and occupancy certificate, if we are not monitoring soil conditions, usage changes and long-term behaviour, we do not have up-to-date information about its real safety.

For a more detailed overview of soil–structure interaction and how it affects building performance, see the technical guidance published by NIST.

2. Where does Structural Health Monitoring (SHM) come in?

Structural Health Monitoring (SHM) is the practice of measuring how a structure actually behaves in real life using sensors and data analytics – either continuously or at regular intervals – in order to detect damage and performance loss as early as possible. Structural Health Monitoring has evolved significantly over the last two decades, with a large body of research demonstrating its effectiveness for bridges, high-rise buildings and other critical infrastructure.

SHM is particularly critical for structures exposed to:

• Soil settlements and tilting (e.g. retaining walls, high-rise buildings, industrial facilities, structures next to deep excavations or tunnels),
• Soft-storey configurations with commercial usage at ground level,
• Older buildings that have previously experienced earthquakes or heavy loading,
• Seismically isolated buildings and special engineering structures,
• Schools, hospitals and other buildings where failure would have severe consequences.

By moving from a one-time “design-only” mindset to a “monitor through the whole life cycle” mindset, SHM helps turn unknowns into measurable quantities.

3. How StructHealth uses SHM to address these risks

You can think of this section as the “StructHealth services” layer within the article. On your website, each part can be visually represented as a card or block.

3.1. Vibration-based performance tracking (modal monitoring)

• Using highly sensitive accelerometers, we measure the structure’s natural frequencies, mode shapes and damping ratios either continuously or at scheduled intervals.
• Significant changes in natural frequencies over time often indicate loss of stiffness due to cracking or weakening of load-bearing elements.
• By comparing the building’s dynamic properties before and after earthquakes – or over several years – we can distinguish between normal ageing and damage that requires intervention.

The StructHealth platform automatically processes these modal parameters and presents them as clear, engineer-friendly dashboards and reports.

3.2. Monitoring soil–structure interaction

• Sensors and/or tilt meters at different corners of the building allow us to track:
  • long-term settlements,
  • tilt (rotation),
  • and differential movements across the footprint.
• This is especially important near metro lines, deep excavations, reclaimed land or areas with changing groundwater conditions.
• With SHM, the effect of construction activities in the vicinity on nearby buildings is quantified with real data, not assumptions.

StructHealth visualises these measurements on maps and floor plans, highlighting areas of concern for engineers and decision-makers.

3.3. Threshold-based automatic alerts

• For each structure, we can define limits for acceleration, tilt, frequency change, crack width or other key parameters.
• When these thresholds are exceeded,
  • site managers,
  • facility operators,
  • or municipal authorities
    receive SMS, e-mail or platform notifications.

This gives stakeholders the chance to act in time – to organise preventive evacuation, detailed inspection or strengthening – instead of reacting after a collapse.

3.4. Rapid post-earthquake condition assessment

• After an earthquake, SHM records the maximum accelerations, displacements and spectral demands actually experienced by the structure.
• These measurements are compared against a pre-defined numerical model / digital twin of the building.
• This helps determine whether the building has been subjected to demands beyond its expected performance level.

For municipalities and large facility owners responsible for dozens or hundreds of buildings, StructHealth supports data-driven prioritisation: which buildings must be checked first, and where to allocate limited engineering resources.

4. Who benefits the most?

SHM and early-warning solutions bring significant value to several key stakeholders:

• Municipalities and public authorities
  • Mapping the risk level of the existing building stock,
  • Identifying priority zones for retrofitting or redevelopment,
  • Monitoring the impact of metro, tunnel and deep excavation projects on surrounding structures.
• Residential building and site managers
  • Understanding how their building actually behaves under real loads,
  • Supporting periodic engineering inspections with instrumented data.
• Industrial facilities and organised industrial zones
  • Monitoring stacks, silos, tanks and critical production lines,
  • Evaluating structural safety and business continuity after earthquakes.
• Education and healthcare buildings
  • Tracking performance in schools and hospitals where life safety is paramount,
  • Accelerating decision-making about usability after seismic events.

5. What does the Gebze incident tell us?

The building collapse in Gebze is not a random outlier. It shows how:

• soil conditions,
• structural design and detailing,
• changes in usage over time,
• lack of maintenance and inspection

can combine into a slow-moving but deadly risk, even when there is no major earthquake.

Three key messages emerge:

1. One-time checks at the design and permit stage are not enough.
   Structures need to be assessed and monitored repeatedly throughout their entire service life.
2. Soil–structure interaction is dynamic.
   Every new excavation, tunnel, fill or change in groundwater can alter the way a building behaves.
3. Data-driven decision-making is no longer optional.
   In critical zones, structural health monitoring has moved from “nice to have” to “essential infrastructure”.

Conclusion: Learning from tragedy – and not repeating it

We extend our deepest condolences to the families affected by the collapse in Gebze.

Instead of treating such disasters purely as matters of fate, we must turn:

• soil investigations,
• periodic assessments,
• sensor-based Structural Health Monitoring systems,
• digital twins and advanced data analytics

into standard practice in our cities.

Whether it is a single apartment block, an industrial plant, a school or a hospital:

If we cannot answer the question “How does this building really behave?”, we cannot be sure about its safety.

Would you like to evaluate your building with StructHealth? (CTA section)

Share a few details about your building or project. Our team will contact you with Structural Health Monitoring and risk assessment options tailored to your needs.

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StructHEALTH proudly shares the successful installation of our cutting-edge sensors at the esteemed Istanbul Technical University (ITU) Nuclear Reactor Building.

Structural Health Monitoring systems have been installed to Ferrero Duzce Factory.

Burdur Hospital is located in western part of Türkiye. The Burdur city prone to Earthquakes.

Real time monitoring is a crucial for valuable structures.

Healthy Structures-Structural Health Monitoring- Earthquake Risk Reduction-Digital Twin-Earthquake Early Warning-Safety Structures

We are thrilled to announce a significant milestone in our journey towards revolutionizing structural health monitoring systems. With great pride and enthusiasm, we share the news of our first successful installation of a cutting-edge structural health monitoring (SHM) system.

Located in IT Valley, Kocaeli-TÜRKİYE this installation marks the beginning of a new era in structural monitoring technology. Our team of experts has worked tirelessly to design and implement a state-of-the-art system tailored to the unique needs of the structure. Through meticulous planning, innovative engineering, and relentless dedication, we have achieved a remarkable feat in enhancing the safety and reliability of our built environment.

Our commitment to excellence extends beyond the installation phase. We remain steadfast in our dedication to ongoing monitoring, analysis, and optimization of the system, ensuring its reliability and effectiveness throughout its operational lifespan.

We extend our heartfelt gratitude to all members of the StructHEALTH team whose unwavering dedication and expertise have made this achievement possible. We also express our sincere appreciation to our valued partners and clients for their trust and collaboration in this endeavor.

As we celebrate this milestone, we reaffirm our commitment to pushing the boundaries of innovation in structural health monitoring. With each installation, we strive to raise the bar and set new standards of excellence in the industry.

Stay tuned for more updates as we continue to pave the way towards safer, smarter, and more resilient structures.

StructHEALTH Technology is a company with a passionate and ambitious team dedicated to pioneering advances in infrastructure resilience and delivering innovative solutions for structural monitoring. Their goal is to redefine industry standards.

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