Post on 08-Apr-2018
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RAILWAY BRIDGE MONITORING
PRESENTED BY
VINEESH K P
10ME63R38
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CONTENTS
OBJECTIVE OF MONITORING
STEPS IN MONITORING
MONITORING TECHNIQUES
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MONITORING OBJECTIVES
Structural assessment
Performance monitoring
Post strengthening monitoring Life time prediction monitoring
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MONITORING OBJECTIVES
STRUCTURAL ASSESSMENT
Monitoring stress, strain, displacement and
acceleration for assessing the globalbehaviour of the bridge.
Monitoring of local strains for assessing the
critical spots against fatigue.
Monitoring of temperature for assessing the
real temperature profiles and their effect on
the bridge.
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MONITORING OBJECTIVES
PERFORMANCE MONITORING
The goal of performance monitoring is to
assess the current performance of a bridgewith respect to serviceability condition.
POST STRENGTHENING MONITORING
Goal is to verify the effectiveness ofstrengthening action.
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MONITORING OBJECTIVES
LIFE TIME PREDICTION MONITORING
Collect real life data that contribute to
estimate the residual life time bridge.
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STEPS IN MONITORING
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DATA ACQUISITION
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DATA ACQUISITION
It deals with the installation of various sensing
elements that can measure the following
Strain Accelerations
Displacement
Temperature
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DATA ACQUISITION
FUNCTIONS OF SIGNAL CONDITIONER
1. Amplification of low level signal.
2. Filtering. Removal of unwanted signal received by the
signal.
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DATA ACQUISITION
DATA ACQUISITION BOARD
Convert the analog signal into digital signal.
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COMMUNICATION OF DATA
It refers to the conveyance of data from the
data acquisition system to the location where
the data is processed.
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DATA PROCESSING
A data processing step is defined by an
algorithm which transform one or more input
data into one or more output data.
It is important that process the data from all
sensors and relate it to a common reference.
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STEPS IN DATA PROCESSING
SPECTRAL ANALYSIS
Decompose the time series into frequency
components.
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STEPS IN DATA PROCESSING
DATA REDUCTION
Data reduction should be considered for every
measurements that needs to be sample with ahigh sampling rate.
METHODS OF DATA REDUCTION
Data compression Data transformation
Data evaluation
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STORAGE AND DIAGNOSTICS
Storage of processed data
Conversion of processed data into quantities
that relate directly to the response of thestructure.
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MONITORING
PERIODIC MONITORING
CONTINOUS MONITORING
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MONITORING TECHNIQUES
VISUAL INSPECTION
Accuracy of inspection depends upon
inspectors experience and skill time- and labour-consuming job
No information about the behaviour of the
strctuture due to dynamic loading.
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MONITORING THROUGH AMBIENT VIBRATION
To determine the vibration characteristics of a
structure excited by wind or human activity or
passage of train
Response is measured by accelerometers
Used for determination of natural frequencies,
structural damping, mode shapes, Damage
detection
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AMBIENT VIBRATION TEST
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AMBIENT VIBRATION TEST
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FREE VIBRATION TEST
It is based on sensing the accelerations of a
freely vibration structure.
The free vibrations can be generated by a train
or releasing the structure from a deformedstructure.
The accelerations data can be used for
extraction of natural frequencies,determination of structural damping and
mode shapes.
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LINEAR EXCITER TESTING
The structure is forced to vibrations by an
exciter, which moves a mass in vertical or
horizontal directions.
The inertial forces of the mass produces
reaction forces on the bridge.
The exciter force and the vibration response of
the structure at different positions are
captured with accelerometers
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LINEAR EXCITER TESTING
It can be sued for determination of natural
frequencies, structural damping, mode shapes
and transfer functions.
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ROTATING UNBALANCED EXCITER TESTING
The structure is forced to vibrations by an
exciter with a rotational mass with
eccentricity.
The centripetal forces of the rotating mass
produce a harmonic reaction forces on the
bridge.
The frequency of the harmonic force is given
by the rotation speed.
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ROTATING UNBALANCED EXCITER TESTING
It can be sued for determination of natural
frequencies, structural damping, mode shapes
and transfer functions
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REFERENCES
O.S.Salawu and C. Williams,Review of full scale dynamic
testing of bridge structures,Journal of engineering
structures,1995, Volume17,113-121
L.Fryba and M.Pirner,Load test and modal analysis of bridge,Journal of engineering structures,2001,volume 23,102-109.
Monitoring guide line for railway bridges,
www.sustainablebridges.com
Guideline for structural monitoring
www.sustainablebridges.com
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THANK YOU