FEA Based Level 3 Assessment of Deformed Tanks with Fluid Induced Loads
Strain measurement in RCC structure
1. 2CL404 Civil Engineering Project
Strain Measurement in RCC
Structure
By:
Ankit Ahir 11BCL003
Rekan Gadhecha 11BCL009
Nakul Gami 11BCL010
Nisarg Gandhi 11BCL011
Guided By:
Prof. Digesh Joshi
2. CONTENTS
• INTRODUCTION
• OBJECTIVES & SCOPE OF PROJECT
• NEED OF PROJECT
• LITERATURE REVIEW
• APPROACH
• TASKS PERFORMED
• TASKS TO BE PERFORMED
3. STARTING WITH THE BASICS…
• What Is Strain?
When External Forces Are Applies On A Object Made Of Elastic Material It Tends To
Change Its Shape And Size
The Relative Change In Shape Or Size Of An Object Due To Externally Applied
Forces Called Strain
• What Is Stress?
The Internal Resistive Force Developed InThe Body DueTo Strain Is Called Stress
4. STARTING WITH THE BASICS…
• Relation Between Stress And Strain
Initially The Stress And Strain Are Directly
Proportional (Up to Point A)
Then As The Strain Increases There Is Some
Permanent Deformation InThe Body
The Region Till Point B Is Called Elastic Region
And The Region Further Is Called The Plastic
Region
5. STARTING WITH THE BASICS…
• What Is Strain Gauge?
A device for indicating the strain of a material
or structure at the point of attachment.
There are some materials whose resistance
changes when strain is applied to them or
when they are stretched and this change in
resistance can be measured easily
It is basically of two types
1) Mechanical strain gauges
2) Electrical strain gauges
6. STARTING WITH THE BASICS…
• MECHANICAL STRAINGAUGE
It is made up of two separate plastic layers.
The bottom layer has a ruled scale on it and
the top layer has a red arrow or pointer.
One layer is glued to one side of the crack
and one layer to the other. As the crack
opens, the layers slide very slowly past one
another and the pointer moves over the
scale. The red crosshairs move on the scale
as the crack widens.
7. STARTING WITH THE BASICS…
• Electrical STRAINGAUGE
When an electrical wire is stretched within
the limits of its elasticity such that it does
not break or permanently deform, it will
become narrower and longer, changes that
increase its electrical resistance end-to-end.
Strain can be inferred by measuring change
in resistance.
8. WHAT IS OUR PROJECT?
• Our Project Is Basically To MeasureThe Strain In RCC Structures
• Our Main Aim Is To Measure Strain In The Concrete Beam As Well As In The
Steel Reinforcement OfThe Beam
9. WHAT IS OUR PROJECT?
• Consider A Simply Supported Beam As Shown In
The Figure
• A Concentrated Load F Is Applied At The Mid
Span OfThe Beam
• The BeamWill Undergo Sagging
• So As Shown In The Figure Surface 1 Will Be
Under Compression And Surface 2 Will Be Under
Tension
• We Measure The Strain In This Two Surfaces And
The Strain In The Reinforcement Of These Two
Regions
10. PURVIEW OF THE PROJECT
• The Project Extends To The Study Of Working, Construction And
Experimental Usage Of Mechanical And Electrical Strain gages For The
Measurement Of Strain
• It Also Covers The Casting And Testing Of PCC Cubes, Beams And Cylinders
And To MeasureThe Strain Electrically And Mechanically
• It Also Includes The Casting And Testing Of RCC Beam And To Measure The
Strain Electrically And Mechanically
11. WHY IS THE PROJECT REQUIRED?
• Strain Can Be Calculated Analytically By Various Methods In The RCC Structure But
Those All Calculations Are Based On Some Assumptions And Can Be Erroneous
• Thus This Experiment Exactly Helps To Calculate The Strain Practically As Well As
Analytically AndThe Error In Both Can Be Calculated
• Also It Will Help To DecideWeather The Reinforcements Of Lower Diameter Can Be
Used ForA Given Load To Resist The Allowable Deflection.
• These Project Helps To Understand The Behavior Of Various Elements Of The RCC
Structure DueTo Applied Load
12. WHAT WE REFERRED?
• We Studied Various Articles And Reports OnTheWorking Of Strain gages
• We Emphasized OnTheWorking Of Electrical Strain gages
• We Also Studied The Procedure To install Electrical And Mechanical Strain gages On
The RCC Structures AndThe Procedure ToTake Readings Of The Strain
• We Studied In Detail:
1. The Type Of Electrical Strain gagesAvailable In The Market
2. The Type Of Electrical Strain gage To Be Used For Measuring Strain Concrete
3. The Type Of Electrical Strain gage Required ToMeasure Strain In Steel
13. WHAT WE REFERRED?
• Student Strain Gage Manual-published By Vishay Measurements Groups Inc.
This Literature Talked All About Various Types Of Strain Gages And Its Use In
Various Criteria
It Says That The Installation And Operating Characteristic Depend On
1) Backing Material
2) Gage Length
3) Gage Pattern
14. WHAT WE REFERRED?
• Strain gages And Instrumentation: Application Note TT-661
This Note Refers To Strain gage Installation For Concrete Structures
It Describes The Procedure To Install Electrical Strain gage
It Includes Following Steps
1) Degreasing 2) Conditioning
3) Filling 4) Layout Lines
5) gage Bonding 6) Soldering
15. WHAT WE REFERRED?
• Report on Direct Tensile strength on concrete by Raghuraj Ranjendra
Vaidya(11MCLC18)
The whole report had different tests and results of direct tensile test on
concrete
It also describes the installation and testing by mechanical strain gage
It enumerates some basic steps to get readings from a mechanical strain
gage
16. APPROACH TO THE PROJECT
• To Achieve Our Aim Of Getting Strain In RCC
Structures
We Will Study The Working & Installation Of
Electrical And Mechanical Strain gages
We Are Going To Cast As Per Given In The
Table ForM25 Grade Concrete
We Will Attach The Electrical Strain gage
And Measure The Strain In Each Of The
Structure Electrically And Mechanically
We Will Compare The Readings Obtained
Analytically And Experimentally
Specimens Nos
PCC Cubes 6
PCC Beams 6
PCC cylinders 6
RCC beams 6
17. What we have done till now..
• We have studied various literature related to our objectives as discussed in
literature review
• We calculated the mix design forM25 grade of concrete
• We also designed RCC beams with under reinforced and over reinforced section
• Then we casted cubes, beams & cylinders from the designed plain concrete mix
• We also casted 3 cubes extra from each batch to test it for the required designed
strength
21. What we have done till now..
• As the results were not satisfactory, we have casted new cubes, beams &
cylinders with different cement and some corrections in the mix design
22. What we will do further…
• We will place an order for the electrical strain gages and the protective
coating required to be done to protect the strain gages while concreting
• After 28 days we will measure the strength of the new cubes casted
• After getting satisfactory results we will install the electrical strain gage on
the PCC specimens and measure the strain electrically and mechanically
• Meanwhile we will construct the reinforcement cage for the RCC beams for
over-reinforced and under-reinforced structure
23. What we will do further…
• We will design the formwork for the beam as per our required dimensions
• We will install the electrical strain gage on the reinforcement at predefined critical
places
• Then we will cast the beam with M25 grade of concrete
• We will then install electrical strain gages on the surface of concrete
• And hence we will measure the strain in the beams electrically and mechanically
• Then we will compare the results obtained by analytical calculations and our
experimental results
