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Sound in engineering
1. ï ï
Dr. ir. Eva Lantsoght
3/2/2018 Sound Applications in Engineering
1
2. ï General applications
ï Applications in bridge engineering
o NDT techniques
o Acoustic emission
o => Proof loading
ï Summary
3/2/2018 Sound Applications in Engineering 2
3. ï Sound in Engineering? Acoustic
Engineering
o Design, analysis and control of sound
ï Applications
o Noise control: reduce unwanted noise
o Ultrasound
o Programming digital sound of
synthesizers
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4. ï Design of building ~ sound experience
ï Depends on the use of the building
o Theatre: good speech intelligibility
o Concert hall: quality of sound of music
o Offices: pleasant space, not too noisy
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6. ï Noise pollution = disturbances caused by unwanted
sounds
o Transport
o Industry
o Recreation
ï Civil Engineering
o Development of better material mixes to reduce noise levels of
traffic
o Open graded asphalt
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7. ï Used in The Netherlands (ZOAB)
ï âWhisper asphaltâ
ï Very porous mix
o More coarse material
o Less fine material
ï Advantages
o Noise reduction: 4dB at 120km/h
o Drainage of water â no aqua planning
o No rutting
ï Disadvantages
o Less friction => longer distance when breaking
o Raveling problems
o Shorter lifetime than regular asphalt
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8. ï Extending the service life of existing bridges
o Improved calculation methods
o Improved inspection methods
o Improved rehabilitation methods
ï Inspection:
o Visual inspection
o Non-destructive inspection
o Destructive inspection
o Proof loading
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9. ï Non-destructive testing method
ï Evaluation of material properties (e.g. E-modulus)
ï For near surface zone
ï Surface wave dispersion
o Velocity of propagation as function of frequency and wavelength
o In layered system
o To obtain information about layer thickness and E
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11. ï More commonly used â with electro-magnetic waves (not
sound waves)
ï Objects inside depth of concrete
o Reinforcement
o Wire meshes
ï Produces contour maps of subsurface features
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12. ï Fast methods:
o Where sound changes from clear ringing to mute and hollow
ï Finds delaminations in concrete
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13. ï Stress-wave based method
ï Detection of defects in concrete
o Delamination
ï Detect wave reflectors
ï Frequency range 3 - 40 kHz
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14. ï Dynamic response characteristics to a given impulse
excitation
ï Lower range than impact echo
o 0 â 1kHz
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15. ï Combine methods to get
overview of condition of
bridge
ï More info: FHWA
o https://fhwaapps.fhwa.dot.gov
/ndep/
16. ï Acoustic waves emitted by material
ï Caused by irreversible change in internal structure
o Crack formation
o Plastic deformation
ï Transient elastic waves
ï < 1kHz â 100MHz
o For applications: 100 kHz â 100 MHz
ï Event => measurement âhitâ
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17. ï Use acoustic emission
during proof loading
ï Information about cracks
before we can see them
ï Combine with other
measurement techniques
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19. ï Levels of assessment of bridges
o Hand calculation
o Linear finite element calculation
o Non-linear finite element calculation
o Probabilistic analysis
o Coupling probabilistic + NLFEA
ï Still uncertainties?
o Proof loading until different load levels
âą No permanent damage
âą Unfit for use level
âą Repair level
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20. ï Extend service life of existing
infrastructure
ï Effect of deterioration of materials
on structural performance
ï Test 1 bridge
o But information valid for subset of
bridge stock
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21. ï Proof loading to assess capacity of
existing bridge
ï Study cracks and deformations for
applied loads
ï Crack formation: acoustic
emissions measurements
ï Ruytenschildtbrug: testing to failure
22.
23. ï Sound in Engineering â many
applications
ï General applications: think
about effects of sound for
buildings, pavements, ..
ï Application to bridges
o NDT techniques for better
inspection
o Acoustic emission as measurement
technique
o Acoustic emission used in proof
loading
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