8th Sem Project Report

1

STRENGTHENING OF LOAD BEARING FRAME WORK

OF RESIDENTIAL BUILDING BEFORE AND AFTER

EARTHQUAKE

2

STRENGTHENING OF LOAD BEARING FRAME WORK

OF RESIDENTIAL BUILDING BEFORE AND AFTER

EARTHQUAKE

A PROJECT REPORT

Submitted by

YAGNIK PATEL (100220106014)

HITESH PANCHAL (100220106040)

MEHUL SOLANKI (100220106053)

In fulfillment for the award of the degree

Of

BACHELOR OF ENGINEERING

In

Civil Department

Government Engineering College, Patan

3

GUJARAT TECHNOLOGICAL UNIVERSITY

4 We hereby certify that we are the sole authors of this project report and that neither any part of this UDP

project report nor the whole of the Project report has been submitted for a degree by other student(s) to

any other University or Institution.

We certify that, to the best of our knowledge, the current Project report does not infringe upon anyone’s

copyright nor violate any proprietary rights and that any ideas, techniques, quotations or any other

material from the work of other people included in our Project report, published or otherwise, are fully

acknowledged in accordance with the standard referencing practices. Furthermore, to the extent that we

have included copyrighted material that surpasses the boundary of fair dealing within the meaning of the

Indian Copyright (Amendment) Act 2012, we certify that we have obtained a written permission from the

copyright owner(s) to include such material(s) in the current Project report and have included copies of

such copyright clearances to our appendix.

We have checked the write up of the present Project report using anti-plagiarism database and it is in the

allowable limit. In case of any complaints pertaining to plagiarism, we certify that we shall be solely

responsible for the same and we understand that as per norms, University can even revoke BE degree

conferred upon the student(s) submitting this Project report, in case it is found to be plagiarised.

Team:-

Enrolment number

Name

Signature

100220106014 Patel Yagnik

100220106040 Panchal Hitesh

100220106053 Solanki Mehul

Place:- Guide:- M.D. Vakil

Date:- Sign:

4

CERTIFICATE

Date:

This is to certify that the dissertation entitled “STRENGTHENING OF LOAD

BEARING FRAME WORK OF RESIDENTIAL BUILDING BEFORE AND

AFTER EARTHQUAKE” has been carried out by YAGNIK PATEL, HITESH

PANCHAL and MEHUL SOLANKI under my guidance in fulfilment of the degree

of Bachelor of Engineering in CIVIL (8th Semester) of Government Engineering

College, Patan during the academic year 2013-14.

Guided by:- Head of the Department

Prof.,M.D.Vakil Prof., V.R.Patel

5

SELF-DECLARATION

We,

YAGNIK PATEL , HITESH PANCHAL and MEHUL SOLANKI the students of CIVIL

ENGINEERING Branch 100220106014, 100220106040, 100220106053 respectively enrolled

at Government Engineering College, Patan hereby certify and declare the following:

• We have not purchased the solutions developed by any 3rd party directly and the efforts are made by me/us under the guidance of guides.

The project work is not copied from any previously done projects directly.

• The project work submitted by us is prepared by us and we fully understand the contents.

We will make best efforts to solve the problems given by the user/ industry. If the project

is in relay model we will share credits with the initial contributors.

Names: YAGNIK PATEL, HITESH PANCHAL, MEHUL SOLANKI

Contact number: 9998887142, 9898382622, 8866131767

Date: Sign:/signs: Place: Patan

6

INDEX

Chapter Page

1. Introduction………………………………………………………………….7

2. Strengthening Methods……………………………………………………....9

� Base Isolation…………………………………………………………....9

� Jacketing………………………………………………………………...16

� FRP Reinforcements………………………………………......................24

3. Design Procedure for Strengthening of using ACI 440.2R-08………………31

4. Excel Program………………………………………………………………..39

5. Comparative study…………………………………………………………...53

6. Conclusion…………………………………………………………………....54

7. References……………………………………………………………………55

7

Chapter-1

INTORDUCTION

The casualties from the earthquakes suffered during the last decade have made it necessary to

control and access buildings that have been constructed without any regard to appropriate

seismic design characteristics. Earthquake poses an important challenge for the art and science of

structural engineering to construct safe structures by proper design procedures. The lack of

adequate knowledge of structural behaviour under seismic loads has claimed many lives and

caused extensive property loss for many decades.

Recent earthquakes in Bhuj and Jammu Kashmir demonstrated the power of nature and the

catastrophic impact of such power upon urban cities. Casualties and damage associated with

older buildings, which were designed and constructed using codes that are now known to provide

inadequate safety, are far worse than that for newer buildings which have been designed and

built in accordance with more stringent code requirements. Earthquake occurrence is uncertain

and can be possible partially for faults. The earthquake predictions cannot be eliminated by the

earthquake events. Therefore the earthquake resistant structure is the only solution for the

damaging effect of earthquake on structures.

With the improvements in the earthquake engineering for new construction, more recent effort

focused on the seismic behaviour of older reinforced concrete frames. The effort of evaluating

and improving seismic performance of building requires a detailed investigation of their

deficiencies with regard to strength, stiffness, deformation capacity. For such detail study of the

structure Performance based earthquake engineering is most essential.

Design for seismic resistance has been undergoing a critical reappraisal in recent years, with the

emphasis changing from “strength” to “performance”. However, over the past 25 years there has

been a gradual shift from this position with the realization that increasing strength may not

enhance safety, nor necessarily reduce damage. The development of capacity design principles

8

was an expression of the realization that the distribution of strength through a building was more

important than the absolute value of the design base shear. It was recognized that a frame

building would perform better under seismic attack if it could be assured that plastic hinges

would occur in beams rather than in columns (weak beam/strong column mechanism), and if the

shear strength of members exceeded the shear corresponding to flexural strength. This can be

identified as the true start to performance based seismic design, where the overall performance of

the building is controlled as a function of the design process.

Before going for the strengthening of structures it is essential to have an idea about the reasons

of failure of the structures and need of retrofitting. In case of reinforced concrete buildings it is

necessary to know about the failure pattern of structures. Generally R.C.C. buildings are

designed from a detailed analysis for dead, live and seismic loads. The reinforced buildings often

get damaged in earthquakes because of lack of good design and faulty reinforcement detailing

practice.

9

Chapter-2

STRENGTHNING METHODS

1) BASE ISOLATION:-

10

INTRODUCTION

In recent years base isolation has become an increasingly applied structural design technique for

buildings and bridges in highly seismic areas. Many types of structures have been built using this

approach, and many others are in the design phase or under construction. Most of the completed

buildings and those under construction use rubber isolation bearings in some way in the isolation

system.

The ideas behind the concept of base isolation are quite simple. There are two basic types of

isolation systems. The system that has been adopted most widely in recent years is typified by

the use of elastomeric bearings, the elastomer made of either natural rubber or neoprene. In this

approach, the building or structure is decoupled from the horizontal components of the

earthquake ground motion by interposing a layer with low horizontal stiffness between the

structure and the foundation. This layer gives the structure a fundamental frequency that is much

lower than its fixed-base frequency and also much lower than the predominant frequencies of the

ground motion. The first dynamic mode of the isolated structure involves deformation only in the

isolation system, the structure above being to all intents and purposes rigid. The higher modes

that will produce deformation in the structure are orthogonal to the first mode and consequently

also to the ground motion. These higher modes do not participate in the motion, so that if there is

high energy in the ground motion at these higher frequencies, this energy cannot be transmitted

into the structure. The isolation system does not absorb the earthquake energy, but rather deflects

it through the dynamics of the system. This type of isolation works when the system is linear and

even when undamped; however, some damping is beneficial to suppress any possible resonance

at the isolation frequency.

The second basic type of isolation system is typified by the sliding system. This works by

limiting the transfer of shear across the isolation interface. Many sliding systems have been

proposed and some have been used. In China there are at least three buildings on sliding systems

that use a specially selected sand at the sliding interface. A type of isolation containing a lead-

bronze plate sliding on stainless steel with an elastomeric bearing has been used for a nuclear

power plant in South Africa. The friction-pendulum system is a sliding system using a special

11

interfacial material sliding on stainless steel and has been used for several projects in the United

States, both new and retrofit construction.

LITERATURE REVIEW

Many researchers have considered various aspects of ground-borne vibration and its effects on

buildings and their occupants, and several detailed studies have already been undertaken. Some

of the papers giving thought to Base Isolation of Buildings, Retrofitting of building by Seismic

Base Isolation and the study of structural response due to actual earthquake are studied and

abstract of the same are presented below.

Yeong-Bin Yang, Kuo-Chun Chang, Jong-Dar Yau [2]

presented the philosophy behind

Seismic Isolation systems, basic requirements of Seismic Isolation systems and the design

criteria for Isolation devices like HDR, LRB & FPS. Example is provided to illustrate the

practical application of the design concept and a comparison is carried out for the three types of

bearings for the same project. It was concluded by the author that the procedures presented2.

Literature Review here serve merely as a key concept involved in initial sizing of the base

isolation systems. Extra care must be given in applying isolators to the rehabilitation of existing

buildings.

Rihui Zhang [3]

presented basic concepts, modeling and analysis for an isolated structure.

Seismic Isolation and Energy Dissipation devices like elastomeric isolators, sliding isolators and

few dampers are presented. This is followed up by performance and testing requirements for

isolation devices. Design guidelines and design examples are presented, where the design

guidelines follow AASHTO guidelines for bridges and UBC guidelines for buildings. This

guideline contains general requirements for isolation, selecting proper isolation device, methods

of analysis, design displacement & design force. Recent development in this field and

application are presented. The author has made an attempt to introduce the basic concepts of

seismic isolation and supplemental energy dissipation devices and their history, current

developments, applications, and design related issues.

12

James M. Kelly [11]

presented the ideas behind the concept of base isolation. In this approach the

building or structure is decoupled from the horizontal components of earthquake ground motion

by interposing a layer with low horizontal stiffness between the structure and the foundation.

Research and development on the use of natural rubber bearings for Isolating buildings from

earthquakes is presented. U.S. applications of base isolation are presented followed by

application of base isolation in Japan and finally the application of base isolation for nuclear

power plants is presented. From the research work carried out it was proved that research has

improved the effectiveness of isolators in decreasing problems of stability, roll-out, failure of

isolators, or unexpected response. The difficulties of manufacturing large isolators have

diminished. It was now possible to make bearings of large diameters, because of the research

work carried out.

Principle of Base Isolation

The principle of Seismic Isolation is to introduce flexibility at the base of a structure in the

horizontal plane. The system operates by decoupling the structure from the horizontal

components of earthquake ground motion by interposing a layer of low horizontal stiffness

between structure and foundation. By using Isolators the building is "decoupled" from the

ground motion of any earthquake and the transmission of seismic energy to the building is

dampened. This is done by lowering the vibration frequency, allowing the building to move or

displace, and lowering the shock acceleration of the seismic event thus reducing the tendency for

the upper floors to move faster than the lower floors.

13

Objective of Base Isolation

The objective of seismic isolation systems is to decouple the building structure from the

damaging components of the earthquake input motion, i.e. to prevent the superstructure of the

building from absorbing the earthquake energy. The entire superstructure must be supported on

discrete isolators whose dynamic characteristics are chosen to uncouple the ground motion.

Some isolators are also designed to add substantial damping. Displacement and yielding are

concentrated at the level of the isolation devices, and the superstructure behaves very much like a

rigid body.

Basic Elements of Base Isolation System

There are three basic elements in any practical Seismic Isolation system. They are:-

1. A Flexible mounting so that the period of vibration of the total system is lengthened

sufficiently to reduce the force response.

14

2. A damper or energy dissipater so that the relative deflections between the building &

ground can be controlled to a practical design level; and

3. A means of providing rigidity under low load levels such as wind and minor EQ.

Base Isolation:- Isolation layer is located on the base of building.

Advantages:

a. Minimal added structural costs.

b. Separation at the level of base is easy to incorporate.

c. Base of Columns may be connected by diaphragm.

D. Easy to incorporate back-up systems for vertical loads.

Disadvantage:

a. May require cantilever pit.

Basement Isolation:- Isolation layer located on the certain story of the basement.

Advantages:

a. No Sub-basement required.

b. Minimal added structural costs.

c. Base of columns connected by diaphragm at isolation level.

d. Back-up system for vertical loads provided by columns.

Disadvantage:

a. May require cantilevered elevated shaft below first floor level.

b. Special treatment required for internal stairways below first floor level.

Storey Isolation:- Isolation layer is located on the top of the first story or certain storey

of super structure.

15

Advantages:

a. Minimal added structural costs.

b. Economic if first level is for parking.

c. Back-up system for vertical loads provided by columns.

Disadvantages:

a. Special detail required for elevators and stairs.

b. Special cladding details required if first level is not open.

c. Special details required for vertical services.

Top Isolation:- Isolation layer is located on the top of the building. It is always used to add 1-

2 stories on the top of existing building for seismic retrofit.

16

2) JACKETING:-

17

INTRODUCTION

Jacketing is the most popularly used method for strengthening of building columns. The most

common types of jackets are steel jacket, reinforced concrete jacket, fibre reinforced polymer

composite jacket, jacket with high tension materials like carbon fibre, glass fibre etc. The main

purposes of jacketing are:-

1. To increase concrete confinement by transverse fibre reinforcement, especially for circular

cross-sectional columuns.

2. To increase shear strength by transverse fibre reinforcement.

3. To increase flexural strength by longitudinal fibre reinforcement provide.

Such types of multi-shaped jackets provide a high degree of confinement by virtue of their shape

to the splice region proving to be more effective. Rectangular jackets typically lack the flexural

stiffness needed to fully confine the concrete. However, circular and oval jackets may be less

desirable due to:

(i) Need of large space in the building potential difficulties of fitting in the jackets with existing

partition walls, exterior cladding, and non-structural elements and

(ii) Where an oval or elliptical jacket has sufficient stiffness to confine the concrete along the

long dimension of the crosssection is open to question. The longitudinal fibers similar to

longitudinal reinforcement can be effective in increasing the flexural strength of member

although they cannot effectively increase the flexural capacity of building frames because the

critical moments are located at beam-column ends where most of the longitudinal fibers are

difficult to pierce through to get sufficient anchorage.

Strengthening of RC beam Several methods are used for strengthening of beam like concrete jacketing, steel jacketing, precast concrete jacketing, external prestressing and FRP wrapping. These methods are explained as follows:

18

Concrete Jacketing Concrete jacketing involves addition of a thick layer of RC in the form of a jacket, using

longitudinal reinforcement and transverse ties. Additional concrete and reinforcement contribute

to strength increase of section. General thickness of jacket is up to 100 mm. The stiffness of the

system is highly increased due to jacketing. For beam section stirrups are required to be anchored

in slab. For column longitudinal bars need to be anchored to the foundation and should be

continuous through the slab. Jacketing requires drilling of holes in existing column, slab, beams

and footings. After jacketing size, weight and stiffness of the column increase.

Concrete Jacketing

19

Methods of Concrete Jacketing

Method-A

In the illustration, Method A will accomplish efficient load transfer if the new portion is cast

with a bond breaker between the new and old concrete.

After most of the drying shrinkage has occurred, the ties that link the old and new concrete can

be installed.

20

The gap between the new portion of the column and the existing member (to be partially

supported by this column) can be filled with dry packing material.

This will allow the new material to share its portion of the load.

Method-B&C

When Methods B and C are used, extreme care should be exercised to select concrete mix

designs with very low shrinkage rates.

Pre placed aggregate concrete generally offers the lowest drying shrinkage; it is, therefore, an

excellent material for column enlargements.

Disadvatages

1. Increasing the size of the element, which make its usage very limited.

2. Difficult to construct in some active buildings such as hospitals, schools because of the

noise of equipments.

3. Needs shuttering, formworks, reinforced steel, concrete, concrete pumps, vibrators, etc.

21

Steel jacketing In steel jacketing encasing the column with steel plates and filling the gap with a non-

shrink grout is carried out. Steel jacketing provides confinement to core concrete. Its

high young’s modulus causes the steel to take a large axial load. General thickness of

grout is 25 mm. Steel jacket is affected by corrosion and impact with coating

materials, so it is not used for columns in river, lake and seas. New longitudinal

reinforcement is set around the existing column, and precast concrete segments are set

around the new reinforcement. All segments are tied together by strands. After

injecting non-shrinkage mortar between the existing concrete and precast concrete

segment, prestressed force is introduced in the strands to assure the contact of the

segments.

Steel Jacketing

22

Research Significance The need to strengthen beams for any structure may arise at any time from the beginning of the

construction phase until the end of the service life or when the structure is distressed. During the

construction phase, the strengthening of beam may be required because of,

• Design errors

• Deficient concrete production

• Bad execution processes

• Situations involving changes in the structure functionality

• The development of more demanding code requirements

During the service life, the strengthening of beam in any structure may arise on account of,

• An earthquake or other such natural calamity

• An accident, such as collisions, fire, explosions, etc.

• Distress in structure due to various physical and chemical factors

To overcome above related to functionality of beam for any structure, jacketing using additional

reinforcement may be carried out for its strengthening. Further, for the damaged beams during

their service life, the repairing of beams may be carried out by grouting and the beams

strengthening by jacketing. Less amount of research has been performed on techniques for

jacketing using dowel connectors alone, bonding agent alone, combined use of dowel connectors

and bonding agent and without using dowel connectors and bonding agent on smooth and

chipped surfaces of the beams. Also less amount of work has been done for comparing

performance of strengthened and repaired and strengthened beams by jacketing. For above

reasons the present work is aimed towards Study of Repaired and Strengthened RC beams using

different jacketing Techniques for smooth and chipped surfaces.

23

Objectives of Study To study various parameters, following objectives are decided for the major project.

1) To evaluate the response of RC beam subjected to loading by measuring structural parameters

such as ultimate load, failure load, maximum displacement, strain variation, failure shape, crack

patterns, etc.

2) To study e activeness of jacketing on the beam using additional reinforcement.

3) To study e activeness of dowel connectors and micro-concrete, bonding agent and micro-

concrete, combination of dowel connectors and bonding agent and micro-concrete and without

dowel connectors and bonding agent and using only micro-concrete for jacketing of the beam.

4) To study the e activeness of above method jacketing when the beam surface is smooth as well

as chipped.

5) To evaluate e activeness of grouting for damaged beams before jacketing.

6) To determine bond strength between old and new concrete for smooth surface and chipped

surface of the beams.

7) To compare behavior of strengthened beams and repaired and strengthened beams for

evaluating efficiency of the jacketing method in case of beams.

24

3) FRP REINFORCEMENT:-

25

INTRODUCTION

The use of fiber reinforced polymers (FRP) as a construction material has increased in recent

years, primarily because of the non-corrosive nature and high tensile strength of the material.

Though the principle application of FRPs has been in the form of glass and carbon sheets for

retrofit and rehabilitation projects, FRP reinforcing bars are being considered as an alternative to

steel reinforcements for use in new reinforced concrete structures. A major challenge for using

FRP re-bars in seismically active regions remains to be their brittle failure characteristics.

Fiber-reinforced polymer (FRP) reinforcements have been used extensively as an alternative

reinforcement material to steel for new construction as well as for strengthening and repair of

existing structures. Strengthening of Reinforced concrete (RC) elements mostly use two methods

EBR (Externally Bonded Reinforcements) method and NSM (Near Surface Mounted) method.

Steel bars have resulted in several disadvantages including difficulty in handling at site and

possibility of corrosion at the adhesive-steel interface. Therefore, the strengthening of concrete

structure by bonding FRP bars to concrete surfaces using polymer adhesives is becoming an

effective way of improving performance of structures. FRP materials are lightweight,

noncorrosive, and exhibit high tensile strength. These materials are readily available in several

forms. FRPs are organized in a laminate structure. Each lamina (flat layer) contains an

arrangement of unidirectional fibers fabrics embedded within a thin layer of light polymer matrix

material.

26

Historical Background In Europe, FRP systems were developed as alternates to steel plate bonding. Bonding steel plates

to the tension zones of concrete members with adhesive resins were shown to be viable

techniques for increasing their flexural strengths (Fleming and King 1967). This technique has

been used to strengthen many bridges and buildings around the world. Because steel plates can

corrode, leading to a deterioration of the bond between the steel and concrete, and because they

are difficult to install, requiring the use of heavy equipment, researchers have looked to FRP

materials as an alternative to steel. Experimental work using FRP materials for retrofitting

concrete structures was reported as early as 1978 in Germany (Wolf and Miessler 1989).

Research in Switzerland led to the first applications of externally bonded FRP systems to

reinforced concrete bridges for flexural strengthening (Meier 1987; Rostasy 1987).

FRP systems were first applied to reinforced concrete columns for providing additional

confinement in Japan in the 1980s (Fardis and Khalili 1981; Katsumata et al. 1987). A sudden

increase in the use of FRPs in Japan was observed after the 1995 Hyogoken Nanbu earthquake

(Nanni 1995).

Researchers in the United States have had a long and continuous interest in fiber-based

reinforcement for concrete structures since the 1930s. Development and research into the use of

these materials for retrofitting concrete structures, however, started in the 1980s through the

initiatives of the National Science Foundation (NSF) and the Federal Highway Administration

(FHWA). The research activities led to the construction of many field projects that encompassed

a wide variety of environmental conditions. Previous research and field applications for FRP

rehabilitation and strengthening are described in ACI 440R and conference proceedings (Neale

2000; Dolan et al. 1999; Sheheta et al. 1999; Saadatmanesh and Ehsani 1998; Benmokrane and

Rahman 1998; Neale and Labossière 1997; Hassan and Rizkalla 2002; Shield et al. 2005).

The development of codes and standards for externally bonded FRP systems is ongoing in

Europe, Japan, Canada, and the United States. Within the last 10 years, the Japan Society of

27

Civil Engineers (JSCE), the Japan Concrete Institute (JCI), and the Railway Technical Research

Institute (RTRI) published several documents related to the use of FRP materials in concrete

structures.

The Canadian Standards Association (CSA) and ISIS have been active in developing guidelines

for FRP systems. Section 16, “Fiber Reinforced Structures,” of the Canadian

Highway Bridge Design Code was completed in 2006 (CAN/CSA-S6-06), and CSA approved

CSA S806-00.

In the United States, criteria for evaluating FRP systems are available to the construction

industry (ICBO AC125; CALTRANS Division of Structures 1996; Hawkins et al. 1998).

FRP consists of two main components:

1. Fibers.

2. Resin or Matrix.

28

Types of FRP Reinforcements

There are main three types of FRP Reinforcements available,

1. Carbon

2. Glass

3. Aramid

Installation of FRP bar

Materials used for installation of FRP bar are epoxy as binder material, white sand and FRP bar.

Pro-portion used for mixing is 1:6 for epoxy sand. Process of installation of the NSM FRP rods

started by cutting the grooves with specified dimensions into the concrete cover in the

longitudinal direction at the tension side and shear side of the beam depending upon the

strengthening conditions. A special concrete saw with a diamond blade is used to cut the

grooves. The remaining concrete lugs formed by sawing the concrete surface is then removed

using a hammer and a hand chisel in such a way that the lower surface became rough. The

grooves are cleaned using air brushing pressure to remove debris and fine particles so as to

ensure proper bonding between the filling material and the concrete. The groove dimensions. The

groove is half filled and the FRP rod is then placed inside and pressed lightly. This forces the

filling material around the FRP rod. More filling material is applied to fill the groove and the

surface is leveled. The beam is left for one week to ensure the filling material gains the adequate

strength.Epoxy is used as filling material.

29

FRP Bars

Preparation of Bond Test Specimens

The structural behavior of RC elements strengthened with NSM FRP rods needs to be fully

characterized, and bond is the first issue to be addressed. Bond is of primary importance since it

is the means for the transfer of stress between the concrete and the FRP reinforcement to develop

the composite action. The objective of this test is to investigate the bond strength between NSM

FRP rods and concrete by changing the bond length of FRP bar. For formation of groove, at the

time of casting of block, wooden plate is installed having size of 5d,10d and 15d on the surface

of block. concrete blocks and cubes. Purpose of casting of cubes is to compare bond strength of

concrete with HYSD bars and GFRP bars. Four cubes and six concrete blocks are cast for the

bond test. GFRP bar and HYSD bar are installed in center of cube at time of casting. Wooden

30

plate is installed in the concrete block. The view of the block after removing the woo den plate

The procedure of installation of the FRP bar is presented.

Details of Instruments

Load, displacement and strain for beam specimens are measured using hydraulic jack,

LVDT and electrical strain gauge respectively. Different instruments used in

experimental work are as follows:-

- LVDT (Linear Variable Differential Transducer)

- De action dial gauge

- Hydraulic Jack

- Mechanical Strain Gauges

- Electrical Strain Gauges

LVDT(Linear Variable Differential Transducer)

LVDT is used to measure displacement of the RC column when the load is being applied on it.

LVDT is attached at the position where de action is to be measured in beam. Strength of the

LVDT sensor’s principle is that there is no electrical contact across the transducer position

sensing element for which the user of the sensor means clean data, infinite resolution and a very

long life. Figure4.21 shows LVDT.

31

De action dial gauge Dial gauge is used to measure displacement of a beam during the load

application. It is fitted in such a way that it touches point at which the measurement of de action

is required for the beam. Dial gauge is used for above application.

Hydraulic Jack

Hydraulic jack of 1000 kN capacity is used. It works based on Pascal’s principle.

Basically, the principle states that the pressure in a closed container is the same at all

points. The pressure is described mathematically by a Force divided by Area.

Therefore, if there are two cylinders connected together, a small one and a large one,

and a Force is applied to the small cylinder, it would result in a given pressure.

Mechanical Strain Gauges (DEMEC)

Mechanical strain gauges are known as DEMEC (Demountable Mechanical) strain

gauges. The DEMEC gauges consist of a digital dial gauge attached to an Invar bar. A

fixed conical point is mounted at one end of the bar, and a moving conical point is

mounted on a knife edge pivot at the opposite end. The pivoting movement of this

second conical point is measured by the dial gauge. A setting out bar is used to

position pre-drilled stainless steel discs which are attached to the structure using a

suitable adhesive. In this way, the strain changes in the structure are converted into a

change in the reading on the dial gauge. Figure 4.24 shows mechanical strain gauge.

The Model P3 Strain Indicator and a strain Recorder is a portable, battery-operated

instrument capable of simultaneously accepting four inputs from quarter- half- and

full- bridge strain-gage circuits, including strain-gage-based transducers. Designed for

use in a wide variety of physical test and measurement applications, the P3 functions

32

as a bridge amplifier, a static strain indicator, and a digital data logger. An extensive,

easy-to-use menu-driven user interface operates through a front-panel keypad to

readily configure the P3 to meet particular measurement requirements. Selections

include active input and output channels, bridge configuration, measurement units,

bridge balance, calibration method, and recording options, among others. Data,

recorded at a user-selectable rate of up to 1 reading per channel per second, is stored

on a removable multimedia card and is transferred by USB to a computer. Figure 4.25

shows P-3 strain indicator. A highly stable measurement circuit, regulated bridge

excitation supply, and precisely settable gage factor enable measurements of 0.1%

accuracy and 1 micro-strain resolution. Bridge completion resistors of 120, 350 and

1000 ohms are built in for quarter-bridge operation.

Properties of FRP Bars

FRP STEEL ALUMINIUM TIMBER

Corrosion Resistance High Low Medium Low

Strength High High High Low

Weigth Low High Low Medium

Electrical Conductivity Low High High Moderate

Thermal Conductivity Very Low High High Low

EMI/RFI Tranparency Yes No No Yes

Fabrication Easy Easy Moderate Easy

Life Cycle Cost Low Moderate Moderate High

Environmental Impact Low High High Low

33

Objectives

� To study utility of NSM FRP reinforcement for strengthening of RC beams

� To evaluate effectiveness of variation in number and diameter of GFRP reinforcement on

comparative flexural performance of RC beams

� To study shear behavior of RC beams by incorporating GFRP reinforcement with variation

in diameter and spacing

� To check suitability of incorporating GFRP reinforcement for improving performance of

damaged and undamaged beams compared to control beams

� To evaluate maximum moment, load carrying capacity, displacement and strain

experimentally and compare with analytical calculations

Advantages of FRP

• Corrosion Resistance.

• Lightweight.

• Ease of installation.

• Less Finishing.

• Less maintenance.

• Ductility of FRP wrapped members improves dramatically.

• They are ideal for external application.

• They are extremely durable.

• They are available in various forms: sheets, plates, fabric, etc.

• They are available in long lengths that eliminates joints and splices.

• They cure within 24 hours.

• Anti-seismic behavior.

34

Literature Survey

Various techniques are available for strengthening of RC elements. Use of Fiber Reinforced

Polymer Composites is the most latest alternative for strengthening of RC elements. FRP

reinforcements have higher tensile strength compared to the steel rods. Use of FRP composites is

not limited to new construction, but they are also used to enhance the structures deficient in

shear information available in literature have been studied related to structural elements

strengthened using NSM FRP reinforcement.

35

Chapter- 3

Design Procedure for Strengthening of using ACI 440.2R-08

Example:-

A simply supported concrete beam reinforced with three No. 9 bars (See below fig.,) is located in

an unoccupied warehouse and is subjected to a 50% increase in its live-load carrying

requirements. An analysis of the existing beam indicates that the beam still has sufficient shear

strength to resist the new required shear strength and meets the deflection and crack-control

serviceability requirements. Its flexural strength, however, is inadequate to carry the increased

live load.

7.32 m

FRP

546

mm 609.6 mm

Elevation

Plan

36

Table:-1

Length of the beam, l 7.32 mm

Width of the beam, w 305 mm

d 546 mm

h 609.6 mm

fc′ 34.5 N/mm2

fy 414 N/mm2

φMn without FRP 361 kN-m

Bars φ= 28.6 mm

Table:-2

Loading/Moment Existing Loads Anticipated Loads

Dead loads wDL 14.6 N/mm 14.6 N/mm

Live load wLL 17.5 N/mm 26.3 N/mm

Unfactored loads (wDL + wLL) 32.1 N/mm 40.9 N/mm

Unstrengthened load limit (1.1wDL + 0.75wLL ) N/A 35.8 N/mm

Factored loads (1.2wDL + 1.6wLL) 45.5 N/mm 59.6 N/mm

Dead-load moment MDL 98 kN-m 98 kN-m

Live-load moment MLL 117 kN-m 176 kN-m

Service-load moment Ms 214 kN-m 274 kN-m

Unstrengthened moment limit (1.1MDL + 0.75MLL) N/A 240 kN-m

Factored moment Mu 304 kN-m 399 kN-m

The existing reinforced concrete beam should be strengthened with the FRP system described in

Table 15.4, specifically, two 12 in. (305 mm) wide x 23.0 ft (7 m) long plies bonded to the soffit

of the beam using the wet layup technique.

37

Table:-3

Thickness per ply tf 1.02 mm

Ultimate tensile strength ffu* 621 N/mm2

Rupture strain εfu* 0.015 mm/mm

Modulus of elasticity of FRP laminates Ef 37,000 N/mm2

Solution:-

Procedure Calculation

Step 1—Calculate the FRP system

design material properties

The beam is located in an interior space and a CFRP material will be used. Therefore, per Table 9.1, an environmental reduction factor of 0.95 is suggested. ffu = (CE)*(ffu*)

εfu = (CE)*(εfu*)

ffu = (0.95)*(621 N/mm2) = 590 N/mm2

εfu = (0.95)*(0.015 mm/mm)

= 0.0142 mm/mm

Step 2—Preliminary calculations

Properties of the concrete: β1 from ACI 318-05, Section 10.2.7.3

Ec = 57,000√fc′ Properties of the existing reinforcing steel: Properties of the externally bonded FRP reinforcement:

β1 = 1.05 – 0.05fc/6.9

= 0.80

Ec = 4700 (34.5)^1/2

= 27,600 N/mm2

As = 3(645) = 1935 mm2

Af = (2 plies)*(1.02 mm/ply)(305 mm)

38

Af = n*tf*wf

= 619 mm2

Step 3—Determine the existing state of

strain on the soffit

The existing state of strain is calculated assuming the beam is cracked and the only loads acting on the beam at the time of the FRP installation are dead loads. A cracked section analysis of the existing beam gives k = 0.334 and Icr = 2471 × 106 mm4 εbi= {MDL(df – kd)}/IcrEc

ebi = {(97.6)*[609.6– (0.334)*(546.1)]}/(2471×

10^6)*(27.6)

= 0.00061

Step 4—Determine the design strain of

the FRP system

The design strain of FRP accounting for debonding failure mode εfd is calculated using

Because the design strain is smaller than the rupture strain, debonding controls the design of the FRP system.

efd = 0.41*[34.5/2*37000*1.02]^1/2

= 0.009 ≤ 0.9(0.0142)

= 0.0128

Step 5—Estimate c, the depth to the

neutral axis

A reasonable initial estimate of c is 0.20d. The value of the c is adjusted after checking equilibrium. c = 0.20d

C = (0.20)*(546.1)

= 109 mm

Step 6—Determine the effective level

of strain in the FRP reinforcement

The effective strain level in the FRP may be found from Eq. (10-3). εfe = 0.003[(df-c)/c] – εbi ≤ εfd

Note that for the neutral axis depth

efe = 0.003*{(609.6-109.2)/109.2} –0.00061≤

0.009

εfe = 0.0131 > 0.009

39

selected, FRP debonding would be in the failure mode because the second expression in this equation controls. If the first expression governed, then concrete crushing would be in the failure mode. Because FRP controls the failure of the section, the concrete strain at failure εc

may be less than 0.003 and can be calculated using similar triangles: εc = (εfe + εbi)[c/(df-c)]

εfe = εfd = 0.009

εc = (0.009 + 0.00061)*[109.2/(609.6-109.2)]

= 0.0021

Step 7—Calculate the strain in the

existing reinforcing steel

The strain in the reinforcing steel can be calculated using similar triangles according to Eq. (10-10).

εs = (εfe + εbi)[(d – c)/(df – c)]

εs = (0.009 + 0.00061)*[(546.1-109.2)/(609.6-

109.2)]

=0.0081

Step 8—Calculate the stress level in

the reinforcing steel and FRP

The stresses are calculated using Eq. (10-11) and Eq. (10-9). fs = Es*εs ≤ fy

ffe = Ef*εfe

fs = (200 kN/mm2)(0.0084) ≤ 0.414 kN/mm2 fs = 1.68 kN/mm2 ≤ 0.414 kN/mm2 Hence, fs = 0.414 kN/mm2 ffe = (37 kN/mm2)(0.009) = 0.33 kN/mm2

Step 9—Calculate the internal force

resultants and check equilibrium

Concrete stress block factors may be calculated using ACI 318-05. Approximate stress block factors may also be calculated based on the parabolic stress-strain relationship for concrete as

εc′ =1.7*(34.5)/27,600 = 0.0021

β1= [4(0.0021) – 0.0021}/{6(0.0021) – 2(0.0021)}

40

follows: β1= (4εc′ ε– c)/(6εc′ 2ε– c)

α1= (3εc′ εc –εc^2)/3β1εc′2 where εc′ is strain corresponding to fc′ calculated as εc′=(1.7fc′)/Ec

Force equilibrium is verified by checking the initial estimate of c with Eq. (10-12). C=(As fs+ Af ffe)/α1 fc′ β1b

= 0.749

α1 = {3(0.0021)*(0.0021) -(0.0021)*(0.0021) /{3(0.749)(0.0021)*(0.0021) = 0.886

c

=(1935.48*414+619*330)/(0.886*34.5*0.749*304.8)

= 149 mm ≠ 109 in. n.g.

So, Revise estimate of c and repeat Steps 6 through 9 until equilibrium is achieved.

Step 10—Adjust c until force

equilibrium is satisfied

Steps 6 through 9 were repeated several times with different values of c until equilibrium was achieved. The results of the final iteration are β1 = 0.786; α1 = 0.928;

C

=(1935.5*414+619*330)/(0.928*34.5*0.786*304.8)

= 131 ___OK

So, the value of c selected for the final iteration is

correct.

Step 11—Calculate flexural strength

Components

The design flexural strength is calculated using Eq. (10-13). An additional reduction factor, ψf = 0.85, is applied to the contribution of the FRP system. Steel contribution to bending:

Mns= As fs ( d-β1c/2) FRP contribution to bending: Mnf= Af ffe( d f- β1c/2)

Mns =( 1935.5*414) {(546.1) –(0.786*131/2)

= 3.963 × 10^8 N-mm

= 396.3 kN-m

Mnf = (619*330) *{(609.6) – 0.786*131/2}

= 1.140 × 10^8 N-mm

41

= 114 kN-m

Step 12—Calculate design flexural

strength of the section

The design flexural strength is calculated using Eq. (10-1) and Eq. (10-13). Because εs = 0.0083 > 0.005, a strength reduction factor of φ = 0.90 is appropriate per Eq. (10-5). φMn = φ[Mns + ψfMnf ]

φMn = 0.9[396.3 kN-m + 0.85(114 kN-m)] φMn = 443 kN-m ≥ Mu = 399 kN-m So, the strengthened section is capable of sustaining the new required moment strength.

Step 13—Check service stresses in the

reinforcing steel and the FRP

Calculate the elastic depth to the cracked neutral axis. This can be simplified for a rectangular beam without compression reinforcement as follows: k = [(ρs* Es/ Ec + ρf* Ef/ Ec

)+2{ ρs* Es/ Ec + ρf* Ef* Ec

(df/d) }]^2 - (ρs* Es/Ec+ ρf* Ef/ Ec)

Calculate the stress level in the reinforcing steel using Eq. (10-14) and verify that it is less than the recommended limit per Eq. (10-6). fs,s = [{Ms + εbi*Af*Ef*(df – kd/3)}(d –

kd)Es] / [As*Es*(d – kd/3) + Af*Ef*(df –

kd/3)*(df – kd)]

fs,s ≤ 0.80fy

See EQUATION NOTE I (SI) after Step 14.

k = 0.343 kd = (0.343)(546.1 mm) = 187 mm See EQUATION NOTE II (SI) after Step 14.

fs,s = 279 ≤ (0.80)*(410) = 330 N/mm2 so, the stress level in the reinforcing steel is within the recommended limit.

Step 14—Check creep rupture limit at

service of the FRP

Calculate the stress level in the FRP using Eq. (10-15) and verify that it is less than creep-rupture stress limit given in

ffs = 0.278*(37/200)*{(609.6-187)/(546-187)}-

(0.00061)*(38)

42

Table 10.1. Assume that the full service load is sustained.

ff,s = fs,s(Ef/Es)*{(df-kd)/(d-kd)} –biEf

For a carbon FRP system, the sustained plus cyclic stress limit is obtained from Table 10.1: sustained plus cyclic stress limit = 0.55ffu

= 38 ≤ (0.55)*(590)

= 324 N/mm2

So, the stress level in the FRP is within the recommended sustained plus cyclic stress limit.

EQUATION NOTE I (SI.):

k = [{0.0116*(200/27.6) + 0.00372*(37/27.6)}^2 + 2{0.0116*(200/27.6) +

0.00372*(37/27.6)609.6/546)}]^1/2 – {0.0116*(200/27.6) + 0.00372*(37/27.6)}

EQUATION NOTE II (SI):

fs,s = [{273,912 + 0.00061*619*37*(609.6 – 187/2)}(546 -187)*200] / 1935*200*(546 – 187)

+ 619*37* (607 – 187/3)(607 – 187)

In detailing the FRP reinforcement, the FRP should be terminated a minimum of ldf, calculated per Eq. (13-2), past the point on the moment diagram that represents cracking. The factored shear force at the termination should also be checked against the shear force that causes FRP end peeling, estimated as 2/3 of the concrete shear strength. If the shear force is greater than 2/3 of the concrete shear strength, the FRP strips should be extended further toward the supports. U-wraps may also be used to reinforce against cover delamination.

43

Chapter-4

EXCEL PROGRAM

(SPREAD SHEET)

(Case I, II, III)

44

Length of the beam l (m) 7.32Width of the beam w (mm) 305d (mm) 546h (mm) 609.6fc' (N/mm^2) 34.5fy (N/mm^2) 414ɸMn (kN-m) 361ɸ (mm) 28.6

Loading/moment Existing loads Anticipated loads

Dead loads wDL (N/mm) 14.6 14.6Live load wLL (N/mm) 17.5 26.3Unfactored loads (wDL + wLL) (N/mm) 32.1 40.9Unstrengthened load limit (1.1wDL+ 0.75wLL) (N/mm) N/A 35.8Factored loads (1.2wDL+ 1.6wLL) (N/mm) 45.5 59.6Dead-load moment MDL (kN-m) 98 98Live-load moment MLL (kN-m) 117 176Service-load moment Ms (kN-m) 214 274Unstrengthened moment limit (1.1MDL+ 0.75MLL) (kN-m) N/A 240Factored moment Mu (kN-m) 304 399

Thickness per ply tf (mm) 1.02Ultimate tensile strength ffu* (N/mm^2) 621Rupture strain εfu* (mm/mm) 0.015Modulus of elasticity of FRP laminates Ef (N/mm^2) 37000

envirommental reduction factor CE 0.95no. of plies n 2k 0.334Icr (mm^4) 2471000000Es (kN/mm^2) 200ɸ (Strength reduction factor) 0.9Ψf 0.85ρs 0.0116ρf 0.00372Ec (kN/mm^2) 27.6

SPREADSHEET (Case I)

Loadings and corresponding moments

Manufacturer’s reported FRP system properties

Constants

45

Ψf 0.85ρs 0.0116ρf 0.00372Ec (kN/mm^2) 27.6

ffu (N/mm^2) 589.95εfu (mm/mm) 0.01425


β1 0.8Ec (kN/mm^2) 27.60624929As (mm^2) 1935Af (mm^2) 622.2

εbi 0.00073278

εfd' 0.008765515εfd 0.008765515

c (mm) (change this to B81 for equilibrium, for iteration) 131.7547482

c (mm) initial value 109.2εfe' 0.010147555εfe 0.008765515εc 0.002618935

εs 0.008234096

fs'(kN/mm^2) 1.646819228fs (kN/mm^2) 0.414

Step 5—Estimate c, the depth to the neutral axis

Step 6—Determine the effective level of strain in the FRP reinforcement

Step 7—Calculate the strain in the existing reinforcing steel

Step 8—Calculate the stress level in the reinforcing steel and FRP

Step-1 : Calculate the FRP system design material properties

Step 3—Determine the existing state of strain on the soffit

Step 4—Determine the design strain of the FRP system

46

fs (kN/mm^2) 0.414ffe (kN/mm^2) 0.324324071

Step 9—Calculate the internal force resultants and check equilibrium

εc' 0.002124519β1 0.782920472α1 0.927536022c (mm) 131.2452285Step-10 Iteration

Step 11—Calculate flexural strength components

Mns (kN-m) 396.2373082Mnf (kN-m) 112.6462378

Step 12—Calculate design flexural strength of the section

ɸMn (kN-m) 442.7879493 OK

Step 13—Check service stresses in the reinforcing steel and the FRP

k 0.313266218f(s,s) (N/mm^2) 246.0336987 OK

Step 14—Check creep rupture limit at service of the FRP

f(f,s) (N/mm^2) 26.36417511 OK

47

Spread sheet-2 (l=5m, load capacity=100%)

Enter the Length of the beam l (m) 5

Enter the Width of the beam w (mm) 305

d (mm) 546

Enter the height of the beam h (mm) 609.6

fc' (N/mm^2) 34.5

fy (N/mm^2) 414

ɸMn (kN-m) 361

ɸ (mm) 28.6


Loading/moment Existing loads

Anticipated

loads

Dead loads wDL (N/mm) 14.6 14.6

Live load wLL (N/mm) 17.5 17.5

Unfactored loads (wDL + wLL) (N/mm) 32.1 32.1

Unstrengthened load limit (1.1wDL+ 0.75wLL) (N/mm) N/A 29.185

Factored loads (1.2wDL+ 1.6wLL) (N/mm) 45.52 45.52

Dead-load moment MDL (kN-m) 45.625 45.625

Live-load moment MLL (kN-m) 54.6875 54.6875

Service-load moment Ms (kN-m) 100.3125 100.3125

Unstrengthened moment limit (1.1MDL+ 0.75MLL) (kN-m) N/A 91.203125

Factored moment Mu (kN-m) 142.25 142.25


Thickness per ply tf (mm) 1.02

Ultimate tensile strength ffu* (N/mm^2) 621

Rupture strain εfu* (mm/mm) 0.015

Modulus of elasticity of FRP laminates Ef (N/mm^2) 37000

Constants

envirommental reduction factor CE 0.95

no. of plies n 2

k 0.334

Icr (mm^4) 2471000000

Es (kN/mm^2) 200

ɸ (Strength reduction factor) 0.9

Ψf 0.85

ρs 0.0116

ρf 0.00372

Ec (kN/mm^2) 27.6

48


ffu (N/mm^2) 589.95

εfu (mm/mm) 0.01425


β1 0.8

Ec (kN/mm^2) 27.60624929

As (mm^2) 1935

Af (mm^2) 622.2


εbi 0.000285753


εfd' 0.008765515

εfd 0.008765515




c (mm) initial value 109.2

εfe' 0.010479739

εfe 0.008765515

εc 0.0025223


εs 0.00784379


fs'(kN/mm^2) 1.568757932

fs (kN/mm^2) 0.414

ffe (kN/mm^2) 0.324324071

Step 9—Calculate the internal force resultants and check

equilibrium

εc' 0.002124519

β1 0.775821531

α1 0.924687402

49

c (mm) 132.8541693

Step-10 Iteration


Mns (kN-m) 396.1105162

Mnf (kN-m) 112.6142989


ɸMn (kN-m) 442.6494033 OK


k 0.313266218

f(s,s) (N/mm^2) 102.5784151 OK


f(f,s) (N/mm^2) 11.72323325 OK

50

Spread sheet (l=10m, load capacity 75%)

Enter the Length of the beam l (m) 10

Enter the Width of the beam w (mm) 305

d (mm) 546

Enter the height of the beam h (mm) 609.6

fc' (N/mm^2) 34.5

fy (N/mm^2) 414

ɸMn (kN-m) 361

ɸ (mm) 28.6


Loading/moment Existing loads

Anticipated

loads

Dead loads wDL (N/mm) 14.6 14.6

Live load wLL (N/mm) 17.5 13.125

Unfactored loads (wDL + wLL) (N/mm) 32.1 27.725

Unstrengthened load limit (1.1wDL+ 0.75wLL) (N/mm) N/A 25.90375

Factored loads (1.2wDL+ 1.6wLL) (N/mm) 45.52 38.52

Dead-load moment MDL (kN-m) 182.5 182.5

Live-load moment MLL (kN-m) 218.75 164.0625

Service-load moment Ms (kN-m) 401.25 346.5625

Unstrengthened moment limit (1.1MDL+ 0.75MLL) (kN-m) N/A 323.796875

Factored moment Mu (kN-m) 569 481.5


Thickness per ply tf (mm) 1.02

Ultimate tensile strength ffu* (N/mm^2) 621

Rupture strain εfu* (mm/mm) 0.015

Modulus of elasticity of FRP laminates Ef (N/mm^2) 37000

Constants

envirommental reduction factor CE 0.95

no. of plies n 2

k 0.334

Icr (mm^4) 2471000000

Es (kN/mm^2) 200

ɸ (Strength reduction factor) 0.9

Ψf 0.85

ρs 0.0116

ρf 0.00372

Ec (kN/mm^2) 27.6

51


ffu (N/mm^2) 589.95

εfu (mm/mm) 0.01425


β1 0.8

Ec (kN/mm^2) 27.60624929

As (mm^2) 1935

Af (mm^2) 622.2


εbi 0.001143011


εfd' 0.008765515

εfd 0.008765515




c (mm) initial value 109.2

εfe' 0.00990071

εfe 0.008765515

εc 0.002691627


εs 0.008593944


fs'(kN/mm^2) 1.718788762

fs (kN/mm^2) 0.414

ffe (kN/mm^2) 0.324324071

Step 9—Calculate the internal force resultants and check

equilibrium

εc' 0.002124519

β1 0.78850619

α1 0.928202679

52

c (mm) 130.2219016

Step-10 Iteration


Mns (kN-m) 396.2668688

Mnf (kN-m) 112.6536841


ɸMn (kN-m) 442.8202502 Not OK


k 0.313266218

f(s,s) (N/mm^2) 356.3336301 Not OK


f(f,s) (N/mm^2) 35.16002075 OK

53

Chapter-5

COMPARATIVE STUDY

Results and conclusion

Case-1 Case-2 case-3

l=7.32m, Load

capacity (150%)

l=5m, Load

capacity (100%)

l=10m, Load

capacity (75%)

design flexural strength of the section

ɸMn (kN-m) 442 442 442

Factored moment Mu (kN-m) 399 142.25 481.5

service stresses in the reinforcing steel

and the FRP f(s,s) (N/mm^2) 278 102.58 356.33

Stress level limit (0.80*fy) 331.2 331.2 331.2

creep rupture limit at service of the FRP

f(f,s) (N/mm^2) 37.77 11.72 35.16

Sustained plus Cyclic stress limit

(0.55*ffu) 324.4065 324.4725 324.4725

Ok/Not ok? OK OK Not OK

Dark cells represents that the current design of beam will not sustain the given loads and moments and

would collapse

54

Chapter-6

Conclusion

As we can see from the result table that if we keep the length of beam 10m, then

even with only 75% load capacity, the beam will most likely collapse, and this is

because if we increase the length of simply supported beam, then even with low

load there will be very high bending moments present in the beam which if

crosses the critical value for a particular material and structure leads the beam to

collapse.

So while designing beams (with FRP) before or after earthquake, we have to

check whether we are putting supports at the safe distance or not, otherwise the

structure may collapse.

Use of FRP sheets indeed provide extra strength to the beam and must be

advisable to use in designing new or damaged structure. It is highly

recommended in earthquake prone areas.

55

Chapter-7

Reference

[1] A. Nadeem W.C. Tang, R.V. Balendran and H.Y. Leung. Flexural strengthening of

reinforced lightweight polystyrene aggregate concrete beams with near-surface mounted gfrp

bars. Building and Environment, pages 1381–1393, 2006.

[2] Raafat El-Hacha and Sami H. Rizkalla. Near-surface-mounted fiber-reinforced polymer

reinforcements for exural strengthening of concrete structures. ACI Structural Journal, V. 101,

No. 5,:717–726, September-October 2004.

[3] J.A.O. Barros, S.J.E. Dias, and J.L.T. Lima. E cacy of cfrp-based techniques for the exural

and shear strengthening of concrete beams. Cement & Concrete Composites,, 29:203–217, 2007.

[4] Khaldoun N. Rahal. Shear strengthening of damaged reinforced concrete beams using nsm

cfrp rods and rebars. pages 1–9.

[5] ACI 440R-96 (Reapproved 2002) State-of-the-Art Report on Fiber Reinforced Plastic (FRP)

Reinforcement for Concrete Structures.

[6] ACI 440.2R-08, Guide for the Design and Construction of Externally Bonded FRP Systems

for Strengthening Concrete Structures.

[7] ACI 318-08, Building Code Requirements for Structural Concrete (ACI 318-08) and

Commentary, An ACI Standard, Reported by ACI Committee 318, Copyright American

[8] www.isiscanada.com, ISIS Educational Module 3, An Introduction to FRP-Reinforced

Concrete.

8th Sem Project Report

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