A UHPC (ultra high performance concrete) presentation projects.Nolan Mayrhofer
UHPC presentation featuring select international Ductal projects. This is an in depth look at the types of architectural projects UHPC is best suited for.
Soil nailing is a technique used to reinforce and strengthen existing ground.Soil nailing consists of installing closely spaced bars into a slope or excavation as construction proceeds from top down.It is an effective and economical method of constructing retaining wall for excavation support, support of hill cuts, bridge abutments and high ways.This process is effective in cohesive soil, broken rock, shale or fixed face conditions.
A UHPC (ultra high performance concrete) presentation projects.Nolan Mayrhofer
UHPC presentation featuring select international Ductal projects. This is an in depth look at the types of architectural projects UHPC is best suited for.
Soil nailing is a technique used to reinforce and strengthen existing ground.Soil nailing consists of installing closely spaced bars into a slope or excavation as construction proceeds from top down.It is an effective and economical method of constructing retaining wall for excavation support, support of hill cuts, bridge abutments and high ways.This process is effective in cohesive soil, broken rock, shale or fixed face conditions.
Autoclaved aerated concrete (AAC) block is a building material made of Portland cement, fine aggregates (fly ash or sand), water and an expansion agent in an autoclaving process heated under pressure which results in the production of air voids in the material, making it less dense, easy to cut/mould and better insulating
Quality Control in Concrete and Durability factors : An overviewbybyRAJESH PRASAD,IRSE, CPM/M, RVNL. KOLKATA. An interesting and informative presentation....
Repair, rehabilitation and retrofitting of structures - RRSShanmugasundaram N
Strengthening of Structural elements, Repair of structures distressed due to corrosion, fire, Leakage, earthquake – DEMOLITION TECHNIQUES - Engineered demolition methods - Case studies.
Concrete is the most widely used construction material in India with annual consumption exceeding 100 million cubic meters.
High performance concrete is a concrete in which certain characteristics are developed for a particular application and environment, so that it will give excellent performance in the structure in which it will be placed.
A high-strength concrete is always a high performance concrete, but a high-performance concrete is not always a high-strength concrete.
This presentation gives a brief introduction on FRC's history, definition and why is it used. Types of FRC's and it's applications is explained in detail in later stages.Also, it covers various properties that affects FRC and a Case study in end.
Strengthening structures via external bonding of advanced fibre reinforced polymer (FRP) composite is becoming very
popular worldwide during the past decade because it provides a more economical and technically superior alternative
to the traditional techniques in many situations as it offers high strength, low weight, corrosion resistance, high fatigue
resistance, easy and rapid installation and minimal change in structural geometry. Although many in-situ RC beams
are continuous in construction, there has been very limited research work in the area of FRP strengthening of continuous
beams.
Transparent concrete is a concrete based building material with light-Tran missive properties due to embedded light optical elements usually Optical fibres. Light is conducted through the stone from one end to the other. Therefore the fibres have to go through the whole object. Transparent concrete is also known as the translucent concrete and light transmitting concrete because of its properties. It is used in fine architecture as a facade material and for cladding of interior walls. In this paper, to integrate the merits of concrete and optical fibre, for developing transparent concrete by arranging the high numerical aperture Plastic Optical Fibres (POF) or big diameter glass optical fibre into concrete. The main purpose is to use sunlight as a light source to reduce the power consumption of illumination and to use the optical fiber to sense the stress of structures and also use this concrete as an architectural purpose for good aesthetical view of the building.
Cracks in concrete are inevitable and are one of the inherent weaknesses of concrete. Water and other salts seep through these cracks, corrosion initiates, and thus reduces the life of concrete. So there was a need to develop an inherent biomaterial, a self - repairing material which can remediate the cracks and fissures in concrete. Bacterial concrete is a material, which can successfully remediate cracks in concrete. This technique is highly desirable because the mineral precipitation induced as a result of microbial activities is pollution free and natural. As the cell wall of bacteria is anionic, metal accumulation (calcite) on the surface of the wall is substantial, thus the entire cell becomes crystalline and they eventually plug the pores and cracks in concrete. This paper discusses the plugging of artificially cracked cement mortar using Bacillus Pasteurii bacteria combined with sand as a filling material in artificially made cuts in cement mortar which was cured in urea and Calcium chloride medium. The effect on the compressive strength and stiffness of the cement mortar cubes due to the mixing of bacteria is also discussed in this paper. It was found that use of bacteria improves the stiffness and compressive strength of concrete. Scanning electron microscope (SEM) is used to document the role of bacteria in microbiologically induced mineral precipitation. Rod like impressions were found on the face of calcite crystals indicating the presence of bacteria in those places.
In this study, bacterial concrete is to be prepared under grade of concrete OPC 43.The design mix proportioning also carried under IS code provision. Testing of specimens are carried at 7 days ,14 days and 28 days of curing by Compression Testing Machine and Universal Testing Machine for corresponding specimens. The Compressive Strength and Flexural Strength of Bacterial Concrete are found.
Here, I attach a PowerPoint presentation created by me for a competition held by UltraTech. Have a look at this and feel free to share your views with me.
Autoclaved aerated concrete (AAC) block is a building material made of Portland cement, fine aggregates (fly ash or sand), water and an expansion agent in an autoclaving process heated under pressure which results in the production of air voids in the material, making it less dense, easy to cut/mould and better insulating
Quality Control in Concrete and Durability factors : An overviewbybyRAJESH PRASAD,IRSE, CPM/M, RVNL. KOLKATA. An interesting and informative presentation....
Repair, rehabilitation and retrofitting of structures - RRSShanmugasundaram N
Strengthening of Structural elements, Repair of structures distressed due to corrosion, fire, Leakage, earthquake – DEMOLITION TECHNIQUES - Engineered demolition methods - Case studies.
Concrete is the most widely used construction material in India with annual consumption exceeding 100 million cubic meters.
High performance concrete is a concrete in which certain characteristics are developed for a particular application and environment, so that it will give excellent performance in the structure in which it will be placed.
A high-strength concrete is always a high performance concrete, but a high-performance concrete is not always a high-strength concrete.
This presentation gives a brief introduction on FRC's history, definition and why is it used. Types of FRC's and it's applications is explained in detail in later stages.Also, it covers various properties that affects FRC and a Case study in end.
Strengthening structures via external bonding of advanced fibre reinforced polymer (FRP) composite is becoming very
popular worldwide during the past decade because it provides a more economical and technically superior alternative
to the traditional techniques in many situations as it offers high strength, low weight, corrosion resistance, high fatigue
resistance, easy and rapid installation and minimal change in structural geometry. Although many in-situ RC beams
are continuous in construction, there has been very limited research work in the area of FRP strengthening of continuous
beams.
Transparent concrete is a concrete based building material with light-Tran missive properties due to embedded light optical elements usually Optical fibres. Light is conducted through the stone from one end to the other. Therefore the fibres have to go through the whole object. Transparent concrete is also known as the translucent concrete and light transmitting concrete because of its properties. It is used in fine architecture as a facade material and for cladding of interior walls. In this paper, to integrate the merits of concrete and optical fibre, for developing transparent concrete by arranging the high numerical aperture Plastic Optical Fibres (POF) or big diameter glass optical fibre into concrete. The main purpose is to use sunlight as a light source to reduce the power consumption of illumination and to use the optical fiber to sense the stress of structures and also use this concrete as an architectural purpose for good aesthetical view of the building.
Cracks in concrete are inevitable and are one of the inherent weaknesses of concrete. Water and other salts seep through these cracks, corrosion initiates, and thus reduces the life of concrete. So there was a need to develop an inherent biomaterial, a self - repairing material which can remediate the cracks and fissures in concrete. Bacterial concrete is a material, which can successfully remediate cracks in concrete. This technique is highly desirable because the mineral precipitation induced as a result of microbial activities is pollution free and natural. As the cell wall of bacteria is anionic, metal accumulation (calcite) on the surface of the wall is substantial, thus the entire cell becomes crystalline and they eventually plug the pores and cracks in concrete. This paper discusses the plugging of artificially cracked cement mortar using Bacillus Pasteurii bacteria combined with sand as a filling material in artificially made cuts in cement mortar which was cured in urea and Calcium chloride medium. The effect on the compressive strength and stiffness of the cement mortar cubes due to the mixing of bacteria is also discussed in this paper. It was found that use of bacteria improves the stiffness and compressive strength of concrete. Scanning electron microscope (SEM) is used to document the role of bacteria in microbiologically induced mineral precipitation. Rod like impressions were found on the face of calcite crystals indicating the presence of bacteria in those places.
In this study, bacterial concrete is to be prepared under grade of concrete OPC 43.The design mix proportioning also carried under IS code provision. Testing of specimens are carried at 7 days ,14 days and 28 days of curing by Compression Testing Machine and Universal Testing Machine for corresponding specimens. The Compressive Strength and Flexural Strength of Bacterial Concrete are found.
Here, I attach a PowerPoint presentation created by me for a competition held by UltraTech. Have a look at this and feel free to share your views with me.
Introduction
Types Of Fibers
Production Of SCFRC
Fresh Concrete Tests
Concrete Mixing And Casting Of Beams
Influence Of Concrete Type And Coarse Aggregate Characteristics On Shear
Influence Of Shear Span To Depth Ratio On Shear
Influence Of Beam Size On Shear
Advantages
Conclusions
References
What is corrosion?
Corrosion mechanism
Protective measures against corrosion
Methods of protecting metals
Corrosion inhibitors and types
Advantages and disadvantages of corrosion inhibitors
Concrete coating
Types and where to use it
Advantages and disadvantages of concrete coating
Final project report on grocery store management system..pdfKamal Acharya
In today’s fast-changing business environment, it’s extremely important to be able to respond to client needs in the most effective and timely manner. If your customers wish to see your business online and have instant access to your products or services.
Online Grocery Store is an e-commerce website, which retails various grocery products. This project allows viewing various products available enables registered users to purchase desired products instantly using Paytm, UPI payment processor (Instant Pay) and also can place order by using Cash on Delivery (Pay Later) option. This project provides an easy access to Administrators and Managers to view orders placed using Pay Later and Instant Pay options.
In order to develop an e-commerce website, a number of Technologies must be studied and understood. These include multi-tiered architecture, server and client-side scripting techniques, implementation technologies, programming language (such as PHP, HTML, CSS, JavaScript) and MySQL relational databases. This is a project with the objective to develop a basic website where a consumer is provided with a shopping cart website and also to know about the technologies used to develop such a website.
This document will discuss each of the underlying technologies to create and implement an e- commerce website.
Industrial Training at Shahjalal Fertilizer Company Limited (SFCL)MdTanvirMahtab2
This presentation is about the working procedure of Shahjalal Fertilizer Company Limited (SFCL). A Govt. owned Company of Bangladesh Chemical Industries Corporation under Ministry of Industries.
NO1 Uk best vashikaran specialist in delhi vashikaran baba near me online vas...Amil Baba Dawood bangali
Contact with Dawood Bhai Just call on +92322-6382012 and we'll help you. We'll solve all your problems within 12 to 24 hours and with 101% guarantee and with astrology systematic. If you want to take any personal or professional advice then also you can call us on +92322-6382012 , ONLINE LOVE PROBLEM & Other all types of Daily Life Problem's.Then CALL or WHATSAPP us on +92322-6382012 and Get all these problems solutions here by Amil Baba DAWOOD BANGALI
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CW RADAR, FMCW RADAR, FMCW ALTIMETER, AND THEIR PARAMETERSveerababupersonal22
It consists of cw radar and fmcw radar ,range measurement,if amplifier and fmcw altimeterThe CW radar operates using continuous wave transmission, while the FMCW radar employs frequency-modulated continuous wave technology. Range measurement is a crucial aspect of radar systems, providing information about the distance to a target. The IF amplifier plays a key role in signal processing, amplifying intermediate frequency signals for further analysis. The FMCW altimeter utilizes frequency-modulated continuous wave technology to accurately measure altitude above a reference point.
Welcome to WIPAC Monthly the magazine brought to you by the LinkedIn Group Water Industry Process Automation & Control.
In this month's edition, along with this month's industry news to celebrate the 13 years since the group was created we have articles including
A case study of the used of Advanced Process Control at the Wastewater Treatment works at Lleida in Spain
A look back on an article on smart wastewater networks in order to see how the industry has measured up in the interim around the adoption of Digital Transformation in the Water Industry.
6th International Conference on Machine Learning & Applications (CMLA 2024)ClaraZara1
6th International Conference on Machine Learning & Applications (CMLA 2024) will provide an excellent international forum for sharing knowledge and results in theory, methodology and applications of on Machine Learning & Applications.
About
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
• Remote control: Parallel or serial interface.
• Compatible with MAFI CCR system.
• Compatible with IDM8000 CCR.
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
• Easy in configuration using DIP switches.
Technical Specifications
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
Key Features
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
• Remote control: Parallel or serial interface
• Compatible with MAFI CCR system
• Copatiable with IDM8000 CCR
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
Application
• Remote control: Parallel or serial interface.
• Compatible with MAFI CCR system.
• Compatible with IDM8000 CCR.
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
• Easy in configuration using DIP switches.
Overview of the fundamental roles in Hydropower generation and the components involved in wider Electrical Engineering.
This paper presents the design and construction of hydroelectric dams from the hydrologist’s survey of the valley before construction, all aspects and involved disciplines, fluid dynamics, structural engineering, generation and mains frequency regulation to the very transmission of power through the network in the United Kingdom.
Author: Robbie Edward Sayers
Collaborators and co editors: Charlie Sims and Connor Healey.
(C) 2024 Robbie E. Sayers
Protection Method and Structural Health Monitoring.pptx
1. I AM MOHANRAJA.G
ME- Structural Engineering
Thanthai Periyar Government
Institute of Technology,
Vellore.
2. CONTENTS
⬥ INTRODUCTION
⬦ Process of Corrosion
⬦ Causes of Corrosion
⬦ Effects of Corrosion
⬥ CORROTION RESISTANT STEEL
⬥ COATINGS TO REINFORCEMENT
⬦ Encapsulation
⬦ Cathodic Protection/Sacrificial Anode
⬦ Cathodic Protection/ Impressed Current
⬦ Alkaline Slurry Coating
⬦ Reinforcement Protection
⬥ CATHODIC PROTECTION
⬦ Sacrificial Anode
⬦ Impressed Current
2
3. STRUCTURAL HEALTH MONITORING
⬥ Objective of Structural Health Monitoring
⬥ Steps of Structural Health Monitoring
⬥ Need for Structural Health Monitoring
⬥ World wide SHM Projects
⬥ How to do SHM in Practice
⬥ Current Practice
⬦ Static Based
⬦ Vibration Based
⬥ SHM by Structural Sys Identification
⬥ Structural Health Monitoring Challenges
⬥ Monitoring Metric
⬥ Application
⬥ Technology Solution
3
4. 4
INTRODUCTION
Premature failure of steel-reinforced concrete
structures has been one of the major problems confronting
civil engineers. The reinforcement used to provide strength to
the concrete structure, in most cases, is found to be the main
culprit. This is primarily due to early corrosion of steel
reinforcement A number of methods and materials have been
developed or are being developed to prevent corrosion of
reinforcement steel. This Seminor reviews the work carried
out so far on reinforcement corrosion, its mechanism and
prevention.
5. 5
Process of Corrosion
⬥ Corrosion of metals is an electrochemical process, involves transfer of charge
from one species to another
⬥ For corrosion to occur, there must be two half cell reactions, one capable of
producing electrons (anodic reaction) and the other capable of consuming
them (cathodic reaction)
⬥ For corrosion of steel, the anodic reaction can be
⬥ And the cathodic reactions can be
6. Causes of Corrosion
⬥ Steel in concrete is usually in a no corroding, passive condition
⬥ However, steel is often used in severe environments where sea
water or deicing salts are present
⬥ When chlorides moves into the concrete it disrupts the passive
layer protecting the steel, causing it to rust and pit
⬥ Carbonation is another cause of steel corrosion, when concrete
carbonates to the level of the steel rebar, the normal alkaline
environment which protects the steel form corrosion is replaced
by a more neutral environment 6
7. 7
Effects of Corrosion
⬥ The formation of rust leads to a loss of bond
between the steel and concrete
⬥ Corrosion of steel produces a bulky reaction
product with volume 7-8 times that of steel
⬥ This puts pressure on the surrounding concrete
cover which first cracks and eventually spalls
⬥ Extensive corrosion of the steel can lead to
mechanical weakening of the reinforced
structure
⬥ The ultimate result can be collapse of the
structure
Image Space
Image Space
8. 8
CORROTION RESISTANT STEEL
What does corrosion resistant means?
Corrosion resistance can be defined as the ability to protect
the substrate from corrosion. In this case coating microstructure, in
particular the appearance of open porosity and cracks, can be more
important than the coating composition.
Corrosion resistant steel are defined as the class of steel that
are inherently resilient to degradation caused by corrosion. A steel
that is not naturally corrosion resistant can be made so by combining it
with small amounts of another metal in a process known as alloying
9. 9
Pure Steel
⬥ Usage of pure steel which is free of
impurities makes it resistive to
corrosion
⬥ An example of such structure using
pure steel is the Iron Pillar in New
Delhi which hasn’t corroded for
hundred of years
⬥ Pure steel, though resistant to
corrosion, will not be strong enough
to be used in structures as the
impurities added increase the
structural strength of steel
Image Space
10. 10
Cathodic Protection
⬥ The steel rebar are coupled with with
reactive metals such as Cu, Zn etc.
⬥ This creates negative charge on the
rebar
⬥ The OH- ions that are produced are
attracted towards the anode made of
Cu or Zn
⬥ Thus the reactive metal is corroded
and the steel is protected
⬥ This method provides non uniform
resistance to corrosion and the steel
further away from anode is corroded
Image Space
11. 11
Epoxy coated rebar
⬥ A fusion based epoxy coating is applied
to steel rebar through shot blasting
⬥ The epoxy coating acts as a protective
layer and prevents the corrosion of steel
⬥ But epoxy coating of rebar reduces the
bond strength between concrete and
steel
⬥ The epoxy coating can be easily
damaged during transportation and
handling, the exposed steel can corrode
under the coating
⬥ The epoxy coating of rebar is expensive
and increases the costs by approx. Rs.
8-10 thousand per ton
Image Space
Image Space
12. 12
Galvanized Rebar
⬥ Galvanized rebar have a protective layer of
zinc metal
⬥ The zinc coating serves as a barrier to
corrosive elements that the rebar is exposed
to when embedded in concrete
⬥ It also provides a level of cathodic protection
where the zinc will preferentially corrode
when in contact with bare steel
⬥ But galvanizing also reduces the bond
strength between rebar and concrete
⬥ The steel is exposed below zinc coating
during cutting and bending
⬥ Galvanizing of rebar is expensive and costs
around Rs. 4000 per ton
Image Space
13. 13
Stainless Steel Rebar
⬥ Stainless steel rebar have inherently good
corrosion resistance
⬥ They don’t have the any coatings which can
chip, crack or degrade and cause corrosion
⬥ Capable of withstanding shipping, handling and
bending
⬥ However, the mechanical properties of
stainless steel are not at par with construction
grade steel (strength ~216MPa)
⬥ Due to reduced strength, the quantity of steel
used is increased
⬥ The stainless steel rebar are prohibitively
expensive and hence are not widely used
Image Space
14. 14
Fiber Rebar
⬥ These rebar are made from fiber-reinforced
plastic
⬥ The material used for fabrication of rebar is
resistant to corrosion
⬥ But it has lower bonding strength with
concrete compared to that of steel as grip is
provided by epoxy coating
⬥ The strength of the material is also lower than
that of steel
⬥ Fiber rebar is are relatively new and therefore
are prohibitively expensive
Image Space
15. 15
Corrosion Resistant Steel (CRS) Rebar
⬥ CRS rebar are inherently resistant to corrosion
⬥ They are manufactured b y adding 0.5% of Copper,
Nickel or Chromium to increase the resistance
⬥ CRS rebar are only Rs. 2-2.5K expensive than normal
rebar and can double the life of structure under
harsh conditions
⬥ The rebar can withstand rough handling and
transportation; can be cut and bend without
lowering their resistance to corrosion
⬥ The mechanical properties of CRS rebar is at par with
normal rebar
⬥ Use of CRS Rebar can provide a cost saving of 4-5%
with welding
Image Space
16. 16
COATINGS TO REINFORCEMENT
⬥ Reinforcing steel is naturally protected from corrosion when
surrounded by an alkaline environment of newly cast , good
quality concrete.
⬥ In certain repair situation, additional protection for the encased
reinforcement is prudent.
⬥ Protection system fall into four categories
⬦ Encapsulation
⬦ Cathodic Protection/Sacrificial Anode
⬦ Cathodic Protection/ Impressed Current
⬦ Alkaline Slurry Coating
⬦ Reinforcement Protection
17. 17
Encapsulation
⬥ Insulating the bar from electrical currents in the surrounding concrete can be
accomplished by encapsulating the bar with epoxy
⬥ When new bars are used, fusion bonded epoxy is provides the best
protection.
⬥ Bard=s are Shot-blasted and heated and powdered epoxy is sprayed into
them under controlled environment.
⬥ In field application where encapsulation of existing bars is necessary, epoxy
resin is sprayed or more commonly, brushed into the bars,
⬥ With field application of epoxy it is very difficult to achieve 100% coverage of
the exposed bars
⬥ Intersections and black side of bar create almost impossible access.
⬥ Encapsulation works well when all bars in the affected member are protected
however, when bars are partially coated either within the repair zone or
adjacent to the repair, electrical currents can become concentrated in the
unprotected bars and accelerated corrosion may be a problem.
18. 18
Cathodic Protection/Sacrificial Anode
⬥ Protecting bars from corrosion can be accomplished by coating them with a
sacrificial metal.
⬥ Zinc is the metal commonly used for this purpose
⬥ Zinc applied to the bars with a brush.
⬥ Recently , Molten zinc has been used(California DOT) as a sacrificial surface-applied
coating.
⬥ This method is used after all surface are repaired.
⬥ The surface-applied zinc is electrically connected to the reinforcing steel .
⬥ Since this method is sacrificial , the service life is dependent upon the degree of exposure
to a corrosive environment and anode activity
⬥ This method of protection is used only on an experimental basis
19. 19
Cathodic Protection/ Impressed Current
⬥ Protecting bars from corrosion can be accomplished by reversing the
electrical current flow which causes the corrosion process.
⬥ Anode are installed on or near the concrete surface and are electrically connected to the
reinforcing bars
⬥ Electrical current is pumped into the circuit protecting the bars
⬥ Impressed current must be balanced with the environment on a continual basis in order
to provide protection.
⬥ Constant monitoring and necessary adjustments are required.
20. 20
Alkaline Slurry Coating
⬥ Like un carbonated concrete , alkaline slurry coating protects the reinforcing
steel from corrosion(Alkaline) fillers.
⬥ Some questions exists concerning whether the epoxy insulates the alkaline fillers from
direct contact with the rebar and whether epoxy provides any benefits other than
electrical insulating the bars.
⬥ There are many unanswered questions regarding reinforcement protective systems and
their effects on surround reinforcement.
⬥ By protecting reinforcement steel in a repaired area we have created an island new
material.
⬥ In doing so, potentially more corrosion could occur than would have originally.
⬥ Only independent research, testing and monitoring will answer these question
21. 21
Reinforcement Protection
⬥ The reinforcement in new construction in can be protected using the
following
⬥ Cement-based coating
⬥ Galvanizing/Zinc-Based paints
⬥ Epoxy Coating
⬥ Bitumen-based paints
⬥ Phosphate coating
⬥ Coating for reinforcement bars must satisfy the following
⬥ Ensure uniform coating on the deformed surface configuration of the bars
⬥ Be flexible enough to allow post-coated bending bars
⬥ Be mechanically stable to sustain handling, transportation and fabrication of
reinforcement
⬥ Provide the facility to easy application
⬥ Resist Corrosion
22.
23.
24.
25.
26.
27.
28.
29.
30.
31.
32.
33.
34. Conclusion
3
4
Cathodic protection is a method to control the corrosion of steel
in contaminated concrete that works by making the embedded
reinforcing steel cathodic. When the steel becomes cathodic,
hydroxyl ions are accumulated around it making it passive for a
longer time. The reinforcing steel is electrically connected to
another metal that becomes the anode with or without the
application of an external power supply. Cathodic protection is
used to protect almost any type of reinforced concrete
structure, including horizontal slabs, walls, towers, beams,
columns and foundations.
35. What is Structural Health Monitoring (SHM)
“The process of implementing a damage
detection and characterization strategy for
engineering structures”
SHM Involves:
Health monitoring
Operational Evaluation
Data Feature Extraction
Statistical Models Development 3
5
36. Objective of Structural Health Monitoring
3
6
Performance enhancement of an existing structure
Monitoring of structures affected by external factors
Feedback loop to improve future design based on
experience
Assessment of post-earthquake structural integrity
Decline in construction and growth in maintenance needs
The move towards performance-based design philosophy
37. Determination of damage existence
Determination of damage’s geometric location
Quantification of damage severity
Prediction of remaining life of the structure
Steps of Structural Health Monitoring
3
7
40. How to Do SHM in practice?
• Visual Inspection
Fully experience-based
Subjective/Non-quantitative
• Non-Destructive Evaluation (NDE)
Various technologies for different purposes
Demands a high degree of expertise
Time consuming and costly
Works only in accessible regions of the structure
Interruption and downtime
Labour intensive and risky
8
41. Current Practice : Visual Inspection
9
vibration-based methods are gaining popularities in
structural health monitoring and damage detection
45. How to Do SHM in practice?
45
Static-Based SHM
• Based on the premise that damage will alter the static
properties of the structure.
– e.g. displacements, rotations
• Drawback
Considerable static deflection requires large amount of
static force
46. How to Do SHM in practice?
46
Vibration-Based SHM
• Based on the premise that damage will alter the dynamic
properties of the structure.
– e.g. structural response, frequencies, mode shapes, damping
or modal strain energy change
• By measuring the structural response by means of sensors
strategically placed on the structure, and intelligently
analyzing these measured responses, it is possible to
identify damage occurrence.
• It can be done either in modal domain or physical domain
47. Vibration Based SHM: Sensors
• Different forms of dynamic structural response:
– Displacement, Velocity,Acceleration,Strain.
– Which ones to measure depends on monitoring conditionsand objectives.
• Sensing technology: an ever emerging field of study
• Based on what to measure, different sensors available:
– Laser Displacement Sensors (LDS)
– Velocity Transducers
– Seismometers
– PiezoelectricAccelerometers
– Strain Gauges
• Most of these sensors can be wirelessly connected 14
49. Vibration Based SHM: Sensors
49
Pros and cons of various types of sensors:
– Bandwidth:
• displacement sensors capture low frequency modes
• acceleration sensors capture high frequency modes
– Global vs. Local:
• strain gauges capture local dynamics better
• accelerometers/displacement sensors measure global
dynamics
50. Vibration Based SHM:Model-Based Techniques
50
*Based on a model (e.g. F.E.) of the monitored structure.
*Optimization based methods:
• An initial model is updated using measured structural response. Also called
FE model updating
• Optimization algorithms are run by iteratively changing the values of
some structural properties (e.g. Young’s modulus), so that the FEM parameters
match measured parameters.
• Measured parameters: Measured responses or some parameters obtained
from measured responses (e.g. modalproperties).
• Usually require repeatedly solving the forward problem.
51. Vibration Based SHM:Model-Based
Techniques
51
Alternatively, inverse problem solution approach:
• Identify modal parameters using some system
identification method.
• Use identified modal parameters to obtain physical
parameter (mass, damping, stiffness) matrices.
• Does not require repeatedly solving the forward
problem, but is more complicated.
52. Vibration Based SHM Model-Based Techniques
52
• PROS:
• Allow damage detection, as well as damage location and extent estimation. May
even be used to assess the damage type and to estimate the structure’s remaining
life, though research is still at its onset in this regard
• CONS:
• Require high user expertise
• Affected by modelling assumptions (e.g. boundary conditions,
number of DOFs, material properties, etc.)
• Often too many unknowns
• Usually computationally expensive
53. Vibration Based SHM:Data-Based
Techniques
53
Data-Based techniques are based on statistical, rather
than physical models of the structure. These methods
are called from the operations itself,and
⬥data-basedbecause the features extracted structural
response are obtained bysimple performed
on the response time histories do not
require any physical model
assumptions. These approaches are often said to “let the
data speak by themselves”.
54. Vibration Based SHM: Data-Based Techniques
54
PROS
• Do not require high user expertise.
• Often coined using machine learning knowledge: highly
computationally efficient and ideal to be automated.
• Takeinto account uncertainties inherently present in SHM.
• Free from modeling assumption induced errors.
CONS
• Without a physical model, can at most reach the second level of the damage
detection hierarchy (damage location).
• Being based on a statistical model of the features, they require
sufficient data to be available.
55. Vibration Based SHM: Uncertainties
55
Many sources of uncertainty in the different stages of SHM: During data
acquisition:
• Measurement noise,
• Environmental effects (different temperature, humidity levels),
• Unknown and nonstationary inputs (traffic, wind, earthquake; may excite
different frequency regions),
• Missing data (not every point on the structure observed).
During feature extraction/modeling/identification:
• Modeling assumptions,
• Errors associated with any numerical method,
• Non-unique identification (many models may fit the measured data
equally well).
56. Courtesy of Prof. E. Chatzi, ETH
SHM by Structural System Identification
56
57. Infrastructure is expected to provide:
reliable service for long periods of time,
Undergoing major technology changes,
spanning several generations and experiencing dramatic
evolutions
Develop Wireless Sensor Networks
Reliable
Energy aware
Smart
Structural Monitoring Challenges
57
58. Some Barriers in SHM up today
Conventional cables
High installation costs
Vulnerable to ambient signal noise corruption
Vulnerable to earthquake conditions
Size and complexity of large structures require
a large number of sensing points to be installed.
58
59. Smart Sensor concept
Earthquake Event
Events Recorded
and stored in BS
Sensors Wake-up
(unique IDs)
Sensors go back
to sleep 59
61. Study-1: G+8 storey RCC BSNL building in Guwahati (Borsaikia, Dutta,
Deb 2011)
• 1st Earthquake (11th Feb,2006) –Depth 33 Km in
Arunachal Pradesh-Tibet Border.
• 2nd Earthquake (12th Aug,2006) –Depth 66 Km in India-
Bangladesh Border. 29
62. Study-1: G+8 storey RCC BSNL building in Guwahati
(Borsaikia, Dutta, Deb 2011)
• Damage has been localized using Parametric State Space Modeling.
• Stiffness of Each storeys has been computed.
2 triaxial force balance in
ground and top floor, 4
uniaxial accelerometers in 1st,
3rd, 7th and top in shorter
direction and 3 uniaxial
accelerometers in 1st, 5th and
top of longer direction.
30
63. Study-2: Milikan Library, CalTech (Clinton et al
2006)
The current (2006) forced vibration
fundamental frequency of east–west is 22%
and of north-south is 12% lower than that
originally measured in 1968
• forced vibrations using varying forces.
• minor earthquake shaking.
• weather conditions (rain and wind
events, extremes in temperature)
Plan dimension is 21m × 22.9m and height
from basement is 48.9m
Sensors are densely mounted on the
building and these are continuously 31
64. Study-3: Long Beach Public Safety Building (LBPSB),
California (Chassiakos et al 2006)
• Six storey rectangular steel building built in 1950s,
having plan dimension of 82.3m × 21.3m.
• Due to 1994 Northridge earthquake this facility
need significant seismic mitigation measures.
• So health of this structure was monitored and it
was retrofitted.
• The ambient vibration data collected before,
during, and after the structural retrofit.
Mode Freq before Retrofit Freq after Retrofit % change
1 0.94 Hz 2.09 Hz 122.34 %
2 1.20 Hz 2.52 Hz 110.00%
3 1.47 Hz 2.87 Hz 95.24%
4 3.00 Hz 5.21 Hz 73.67%
5 4.25 Hz 7.60 Hz 78.82%
32
65. Study-3: Long Beach Public Safety Building (LBPSB),
California (Chassiakos et al 2006)
Finite element
model of pre-
retrofit Long Beach
Public Safety
Building
65
Finite element model of
post-retrofit Long Beach
Public Safety Building.
66. Application of SHM in ‘Housing for All’
Project
66
North-East India is prone to earthquake hazards
So monitoring is important to reduce seismic hazard
Proposed Idea: One house will be properly instrumented among a
colony of houses
Sensor data will be taken once in a year and the health of that
colony can be estimated
Visual inspection and NDTs will be done in a regular basis
This will also be used for post-earthquake health assessment and
validate retrofitting operations