INVESTIGATION OF RAILWAY BRIDGE USING ACCELEROMETER AND STRAIN GAUGES

International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056

Volume: 13 Issue: 04 | Apr 2026 www.irjet.net p-ISSN: 2395-0072

INVESTIGATION OF RAILWAY BRIDGE USING ACCELEROMETER AND STRAIN GAUGES

Dr. Mulpuru Madhuri, Bandi Sameer, Kanuri Devi Sri Lakshmi Prasanna, Maddu Ganesh Manikanta, Pothina Rakesh

Department Of Civil Engineering Sanketika Vidya Parishad Engineering College (Approved by AICTE, New Delhi, Accredited by NAAC-A and Affiliated to Andhra University) P.MPalem, Behind International Cricket Stadium,VISAKHAPATNAM-530041

Abstract – Heavy trains cross railway bridges, pushing them with moving forces that might lead to issues like bending, tiny breaks, or material wear over time. Because of this stress, watching how these structures behaves matterssafety depends on it. Looking closely at two different kindsa metal one near Yelamanchili and a solid concrete type in Kadapa - helps spot differences through health-tracking methods. Sensors that catch shaking and sensors measuring internal stretch recorded data when trains passed by. The flexible steel version reacted with more movement, whereas the rigid concrete model stayed calmer, showing less shake during use. When sensors like accelerometers team up with strain gauges, measurements get sharper for checking how bridges behave. Evidence shows these tools catch shifts in structure, shape upkeep schedules better, while quietly boosting both safety and lifespan on train spans.

Key Words: Railway Bridge, Accelerometers, Strain gauges, Structural health monitoring, vibration analysis, Dynamic loads, Stiffness, Bridge safety.

1. INTRODUCTION

Heavy trains pass over railway bridges, so these structures face shifting pressures that may lead to cracksorwear.Becauseofthisstress,watchinghow they behave matters a lot. One example looked at a metalbridgenearYelamanchili,anotherataconcrete one in Kadapa. Scientists applied tools like motion sensors and tension detectors. These recorded how each bridgeshook andstretched whentrains moved across. What happens underneath reveals what the eyecannotsee.Fromthedata,itbecomesclear-steel bridgesshakemorebecausetheybendeasier.Onthe flip side, concrete ones stay calmer thanks to their rigidnature.Monitoringthroughsensorsworkswell, catchingissuesearly.Thisapproachhelpstrackhow structures behave over time. Problems get spotted before they grow serious. Maintenance improves whenguidedbyrealmeasurements.Safetyclimbsas aresultofconstantobservation.

1.1 Importance of Railway Bridges

Heavy trains cross rivers, roads, or deep gaps on railwaybridges-thesecrossingsmustholdupunder constant stress. Built tough, they face both steady weight and sudden forces all day long. Safety depends on their ability to last without weakening overtime.

1.2

Need for Structural Health Monitoring (SHM)

Over time, repeatingloads alongwith weather shifts slowly wear down materials in train bridge parts. Watching how these structures behave day by day offersclearsignswhensomethingbeginstoweaken. Spot checks happen less often now since live data streams show problems before they grow. Fixing small issues early keeps bigger breakdowns from happeninglateron.

1.3 Behavior of Bridges under Train Loads

When trains move across bridges, shaking happens along with shifts in shape and changes to internal forces. Because of this motion, engineers watch how weightspreadsthroughmaterials,noticeweakspots, thencheckifeverythingworksasexpected.

1.4Aim of the Study

From vibrations and strain readings captured by monitoring tools, differences in how steel versus concreterailbridgesrespondareexamined.Because trains create shifting forces, the way each material handles stress becomes clearer over time. When movement patterns change, signs of wear or harm might show up early. Through these measurements, upkeep needs come into view without waiting for visible flaws. Safety grows when hidden shifts in structure reveal themselves ahead of failure. Long term trust in bridges depends on catching small

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issues before they grow large. Maintenance works betterwhenbasedonrealresponsesinsteadoffixed schedulesalone.

SCOPE OF THE PROJECT

Lookingintotworailwaybridgesformsthecorehere - one made of steel located at Yelamanchili, another of concrete at Kadapa - both examined through StructuralHealthMonitoringmethods.Vibrationand strain are captured while trains pass, thanks to sensors like accelerometers and strain gauges fixed ontothestructures.Fromthesereadings,patternsin how each bridge moves and handles force begin to emerge clearly. Though built differently, their realworld reactions under load reveal distinct traits when studied closely. Data shapes the comparison betweenthemetalandconcretespans,showinghow each manages stress over time. What stands out is not just material but response, measured precisely acrossrepeatedtrials

OBJECTIVES OF THE PROJECT

1. To study the concept of structural health monitoringinrailwaybridges.

2. To understand the workingof accelerometersand straingauges.

3. To measure vibration responses using accelerometers.

4. To measure strain in bridge components using straingauges

5.Lookingathowsteelandconcretebridgesrespond whentrainspassoverthem.

6. To compare the performance of Yelamanchili (steel)andKadapa(concrete)bridges.

7.Checkinghowwellsensorsspotshiftsinstructure.

8. To improve bridge safety and maintenance planning

SENSORS CONNECTION LAYOUT

-1:Sensor’sconnectionlayout

Here comes the setup - strain gauges linked with accelerometers for checking bridge health. Wires meet terminals just right, showing how each piece hooks up. Diagrams guide the layout, clear but not fancy. Power flows where needed, arranged so nothing misses a beat. Vibration rides alongside strain, both tracked steady. Data piles up from rails above,feedingchecksonhowwellthingshold.Safety leansonthesenumbers,quietbutfirm.Performance getsitsproofhere,onereadingatatime.

-2:Sensor’sconnectionlayout

Sunlight feeds the setup through photovoltaic cells. Stored energy moves under control to keep things running steady. Sensors on the bridge - ones that trackvibrationsandonesmeasuringtension-gather details constantly. Power flows without interruption thanks to smart management of reserves. This way, readings come in nonstop while using minimal

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resources. Safety climbs because changes show up early. Long spans of usage test how well everything holds up over years. Information builds slowly, paintingaclearpictureofstructuralhealth.

METHODOLOGY

Process 1: Selection of Railway Bridge

Process 2:.Installationofsensors

 Visual Condition Study

Surface Cleaning and Preparation

-0072

Fixing strain gauges on both bridges

Placement of Accelerometers and sensors

Process 3: Data Collection During Train Movement

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6: Identification of Maximum Strain and Time Period from Graph at steel and concrete bridge

Underthegivenloads,safetyperformanceemerged clearly.Fromstraindata,stresslevelsinstructural partsfollowedHooke’sprincipleofelasticity.Where steelreactedsharply,concreteheldsteadywithout notableshift.Loadeffectsstayedwellwithinsecure marginsthroughouttesting.

StressiscalculatedusingHooke’sLaw,wherestress isdirectlyproportionaltostrain.

σ=Stress(N/m²orMPa)E=ModulusofElasticityof material (forsteel≈200GPa,forconcrete≈25GPa)

ε=StrainUsingthemaximum

International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056

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Steel Bridge (Yalamanchili):

Strain=150µε=0.000150,E=200,000MPa

Stress=30MPa→Higherbutsafe

Concrete Bridge (Kadapa):

Strain=150µε=0.000150,E=25,000MPa

Stress=3.75MPa→Safeandstable

Process 8 : Natural Frequency Calculation

Thenaturalfrequencyofeachbridgewasdetermined from the acceleration-time data. The steel bridge demonstrated higher stiffness, whereas the concrete bridge was more flexible but stable, reflecting their respectivedynamiccharacteristics.

Formula: f=1/T

Steel Bridge (Yalamanchili):

T=0.05sec

f=1/0.05= 20 Hz

Concrete Bridge (Kadapa):

T=0.125sec

f=1/0.125= 8 Hz

Process 9: Dynamic Amplification Factor (DAF)

Surprisingly, the DAF analysis revealed how movementchanges things whenstacked againststill loads. One thing became clear - when vibrations enter the picture, both bridges react in ways standard tests miss entirely. The metal structure? It danced more under shifting forces than its counterparteverdid.

Formula: DAF = Dynamic Response / Static Response

Steel Bridge (Yalamanchili):

Yd=10mm,ys=5mm→DAF=10/5=2.0

Concrete Bridge (Kadapa):

Yd=6mm,ys=4mm→DAF=6/4=1.5

Process 10: Allowable stress and safety comparisons

Under pressure tests, each bridge handled force as expected. Safety margins lined up with required standards, showing no risk of failure. Where steel stood strong, concrete did too - both coping well under demand. Load performance matched design goals without issue. Stress levels stayed below maximumssetbyguidelines.

Allowable Stress & Safety Comparison

Steel Bridge (Yalamanchili):

ClculatedStress=30MPa

AllowableStress=250MPa

Status: Safe

Concrete Bridge (Kadapa):

CalculatedStress=3.75MPa

AllowableStress=5MPa

Status: Safe

Process 11: Safety actor calculations

Thebridge'sabilitytohandleweightsafelyshowsup inanumbercalledthesafetyfactor.Thisvaluecomes from dividing strength by expected load. Heavy traffic demands higher margins. Engineers check materials closely before deciding on numbers. Realworld conditions change how much stress a structure can take. Past performance helps guide future designs FOS means you take the stress something can handle, then divide it by what it actually faces.Whatyougetshowshowmuchextra load it could survive before failing. When FOS increases, safety improves too. The greater the number, the less likely failure becomes. Strength goes up as that figure climbs. Safety grows right along with it. A bigger margin shows things can handle more stress. The Yalamanchili steel bridge stands strong, its factor of safety measured at 8.33. Safety like that doesn’t come by accident - built in through careful design. This number means stress levels stay far below failure points under normal loads. Engineers checked every part before giving

approval. High margin? Yes - but needed for longterm reliability. Eight point three three isn’t just a figure-itreflectsreal-worldtoughness.

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The Kadapa concrete bridge holds steady with a factorofsafetyat 1.33 -itsstrengthstandsupwhen tested against real-world forces. Safety here isn’t assumed; numbers backhow well it bears load after load.

Process 12 : Structural safety evaluations

Checking bridge safety involved looking at stress levelsalongsidewhatthoselevelsshouldstayunder. Natural vibrations gave clues about structural behavior instead of just static measures. Impact effects appeared through something called DAF rather than pure load numbers. Strength margins showed up in FOS values, offering another layer beyondbasiccapacity.Eachfactorplayedaroleapart from the others, yet together they shaped the full picture. Steel Bridge Yalamanchili stress frequency DAF safety factor within limits Concrete Bridge Kadapa stress frequency DAF safety factor within limits.

Process 13: Final assessment of bridge

Stresschecks,howoftentheyvibratenaturally,their reaction to moving loads, and safety margins were usedto testthe Yalamanchilisteel bridgealongwith theKadapaconcreteone.Thoughbuiltfromdifferent materials, each stayed below maximum permitted stress levels during testing. Vibration patterns sat well within ranges considered secure, meaning shaking won’t grow out of control. Responses under load changes remained predictable, thanks to low dynamic amplification readings. Safety numbers came back solid - no red flags there. With greater rigidity, the metal structure reacted more firmly when tested. Meanwhile, the concrete version handled everything steadily, without surprise shifts. Built differently, yet both stand ready for regular trafficwithoutconcern.

OBSERVATION OF STRUCTURAL RESPONSE

The structural response of the two railway bridges was observed using accelerometers and strain gauges during train movements. Key observations include:

Vibration Response: The steel structure near Yelamanchili swayed more, being less rigid. On the opposite end, Kadapa's concrete crossing stayed steadierthankstoitsfirmbuild.

Strain Response: Midway along the beam, sensors showed greater tension building up. Where forces piled on most, especially by the ends, stretching reached its peak. Readings shifted noticeably depending on which part of the structure was measured.

Dynamic Behavior: Flexing slightly when trains passed, each bridge held up without issue. Not once did they sag too much or shake in strange waysproof enough they’re sound. A smooth ride every timemeantallwaswellunderneath

Load Effects: The bridges showed predictable increases in strain and vibration with higher train speedsorheavierloads.

Sensor Performance: Sensors that measure movement along with devices tracking material stressdeliveredpreciseupdatesinstantly-thismade it possible to watch howthe bridge responded at all times.

From these findings, it's clear that using sensors helps track how railroad bridges react at any given moment. Tracking stress spots becomes possible whendataflowscontinuouslyfrommonitoringtools.

International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056

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Safety assessments gain accuracy once live measurements are taken into account across entire structures

CONCLUSION

1. Study conducted on steel bridge (Yelamanchili)andconcretebridge(Kadapa)

 NaturalFrequency:

Steel:20Hz

Concrete:8Hz

 DynamicAmplificationFactor(DAF):

Steel:2.0

Concrete:1.5

 StressValues:

Steel:30MPa(Safe)

Concrete:3.75MPa(Safe)

 FactorofSafety(FOS):

Steel:8.33

Concrete:1.33

2. Steelbridgeshowshighervibration(flexible)

3. Concretebridgeshowslessvibration(stiffer)

4. Sensorsprovidedaccuratereal-time measurements

5. Bothbridgesarestructurallysafeundertrain loads

6. SHMsystemiseffectiveformonitoringand safetyimprovement

REFERENCES

Strength of Materials & Mechanics of Materials

 Bansal, R. K. – Strength of Materials Used for basic concepts of stress, strain, and Hooke’s Law(σ=Eε).

 Hibbeler, R. C. –Mechanicsof MaterialsUsed for understanding material behavior, deformation,andelasticity.

Structural Analysis

C. S. Reddy – Structural Analysis Used for load distributionandbehaviorofstructuralmembers.

Structural Dynamics

• S. Rajasekaran – Structural Dynamics Used for natural frequency, vibration, and dynamic responseanalysis.

Structural Health Monitoring (SHM)

•C. R. Farrar & K. Worden – Structural Health Monitoring Used for sensor-based monitoring andbridgeperformanceanalysis.

• Various research papers on SHM Used for advanced concepts of damage detection and monitoring.

Indian Standard (IS) Codes

ThefollowingcodesarepublishedbytheBureau of Indian Standards (BIS), India and used for designandsafetyevaluation:

• IS 800:2007 – General Construction in Steel Usedforsteeldesignandallowablestresslimits.

• IS 456:2000 – Plain and Reinforced Concrete Usedforconcretedesignandstructuralbehavior.

• IS 1893 (Part 1):2016 – Earthquake Resistant Design Used for dynamic analysis and vibration effects.

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