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Analysis Model and Displacement Measurement. Prof. Ho-Kyung Kim (Seoul Nat’l Univ.) Prof. HaeSung Lee (Seoul Nat’l Univ.) Prof. Nam- Sik Kim (Pusan Nat’l Univ.). Korean group. Analysis model and displacement measurement Seoul National University (SNU)

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analysis model and displacement measurement

Analysis Model and Displacement Measurement

Prof. Ho-Kyung Kim (Seoul Nat’l Univ.)

Prof. HaeSung Lee (Seoul Nat’l Univ.)

Prof. Nam-Sik Kim (Pusan Nat’l Univ.)

korean group
Korean group
  • Analysis model and displacement measurement
    • Seoul National University (SNU)
  • Visual inspection and condition assessment
    • PEC (Pyunghwa Engineering Consultants)
    • KCQR (Korea Construction Quality Research Center)
    • Inha Univ.
  • Model updating for the SMART load rating
    • KEC (Korea Expressway Corporation)
    • Sejong Univ.
  • Application of NDT techniques for online monitoring
    • KAIST
  • 4 universities and 3 companies
target span
Target span
  • Southbound of Span 2
    • Severe vibrations have been observed.
    • The longest span length
    • Deteriorations on bearings, bracings and cracks on pier cap
    • Controlled loading test data is available (tested by Drexel Univ.)
fea software
FEA Software
  • MIDAS Civil 2006
    • Database including live load models in the design specification of Korea, U.S., etc.
    • Sectional properties of structural members (such as bracing, diaphragm) are easily obtained using in-built database.
fe modeling
FE modeling

Plate elementfor flange

Plate elementfor web

* 8 node 3D solid element (Isometric formulation with incompatible modes)

**3 or 4 node 3D plate element (Kirchhoff Plate Theory)

  • RC Slab :*solid element
  • Girder
    • Web & flange : ** plate element
fe modeling1
FE modeling

Bracing

Diaphragm

Bracing, diaphragm : 2 node space frame elements

fe modeling2
FE modeling
  • Variation of flange thickness
    • Top flange with two thicknesses
    • Bottom flange with three different thicknesses
    • Sectional properties are varied according to flange details
boundary conditions
Boundary conditions

Fixed bearings

Movable bearings

P1W

P2W

y

x

  • Fixed bearing
    • Between girders and pier 1
    • Rotation in y direction is released
  • Movable bearing
    • Between girders and pier 2
    • Rotation in y direction, translation in x direction are released
measurement of displacement
Measurement of displacement
  • Direct measuring with LVDT
  • Reconstruction from ACCELEROMETER
  • Identification from images of CAMCORDER
reconstruction of displacement from measured acceleration
Reconstruction of displacement from measured acceleration
  • Variational Statement for the Minimization Problem
  • Integration by Parts Twice
  • Governing Equation and Boundary Conditions
    • The same governing equation for a beam on elastic foundation
    • Discretization of governing equation yields FFIR type filter for reconstruction
dynamic displacement
Dynamic displacement
  • Measured Displacement
    • The static displacements are included in measured displacements.
    • To eliminate the static components from the measurements, a moving average technique is employed.
reconstructed displacements
Reconstructed displacements
  • Results
  • LVDT
  • ACC Reconstruction
displacement from camcorder images
Displacement from camcorder images
  • Digital Image Processing Algorithm

Image Arrangement

Grid Generation

(

Target Image

)

Correlation Size Selection

(

ROI

)

Sum Table Calculation

NCC Computation

ROI

ROI

ROI

Target

Target

Target

Searching for the position where the maximum value of Normalized Cross Correlation Coefficient is obtained

Initial coordinate

Coordinates of best

Coordinates of best

(

x

,

y

)

match

(

x

,

y

)

match

(

x

,

y

)

1

1

2

2

3

3

Frame

1

(

t

)

Frame

2

(

t

)

Frame

3

(

t

)

0

1

2

Enhancing the resolution of displacement responses by using the 2nd Order Polynomial Transform Function

Sub

-

pixel Estimation

Displacement Response

identification of displacement from camcorder images
Identification of displacement from camcorder images
  • Measurement conditions

Target Span

Span-2

Target(L/2)

Span-2

Camera Image

Camcorder

SAMSUNG VM HMX10A

Sampling Rate

LVDT : 100Hz

Camcorder : 60fps

Resolution

1280 x 720 pixels (Full High Definition)

50mm/101pixel s= 0.495mm/pixel

Target

(2L/3)

Target

(L/2)

Target

identified displacements
Identified displacements
  • Comparison of Responses on LVDT

Vertical

Vertical

time plan and future test bed in korea
Time plan and future test-bed in Korea
  • Time plan
  • Future test-bed in Korea
  • A new KEC project for evaluating the load carrying capacity of bridges will start from July 2011 to December 2013.
  • Reliability-based approaches will be examined.
  • A typical concrete bridge and a steel bridge will be selected and tested in 2012 and 2013.
  • The bridges will be open for testing to international society.
  • Typical sensors will be installed by Korean side.
time plan and future test bed in korea1
Time plan and future test-bed in Korea
  • Equations for Load Rating
  • AASHTO LRFR
  • CHBDC

Live Load Capacity Factor

Mean Load Method

RC-T Beam

PSC Beam

korean group and ibs supporters
Korean group and IBS supporters

Many thanks to Jeff and Prof. Aktan for their sincere assistance.