graduation project (1) strengthening of an existing reinforced concrete structure student name id...

Graduation Project (1)Graduation Project (1)

Strengthening of an existing Strengthening of an existing reinforced concrete structurereinforced concrete structure

Student Name Student Name ID No. ID No.

Nabil Raweh QahtanNabil Raweh Qahtan 980410066 980410066

Mohammed Eisa Al-HarrasiMohammed Eisa Al-Harrasi 980710101 980710101

Hazem Bakri Al-NaserHazem Bakri Al-Naser 199901443 199901443

United Arab Emirates University

College of Engineering

Civil and Environmental Department

Instructor: Dr. Ashraf Biddah

IntroductionIntroduction

Exclusive SummaryExclusive Summary

The general idea of the project.The general idea of the project.

Problems Facing reinforced Problems Facing reinforced concrete structures.concrete structures.

Exclusive SummaryExclusive Summary

The main achievements:The main achievements: Studying the Strengthening Methods.Studying the Strengthening Methods. Selection of an exiting building.Selection of an exiting building. Experimental Test.Experimental Test. Beginning of Structural Analysis.Beginning of Structural Analysis.

The general idea of the projectThe general idea of the project

The owner of a residential building wanted to The owner of a residential building wanted to convert his building to a commercial building.convert his building to a commercial building.

According to change in the use of existing According to change in the use of existing structure, the structural system of the structure, the structural system of the building will be modified to fit the new building will be modified to fit the new changes.changes.

PROBLEM: The old building cannot carry the PROBLEM: The old building cannot carry the new loads that come from the changes. new loads that come from the changes.

DESIGN BRIEF : Design a strengthening DESIGN BRIEF : Design a strengthening system that can increase the capacity of the system that can increase the capacity of the existing structural system to be able to carry existing structural system to be able to carry the new loads that come from the changesthe new loads that come from the changes..

Problems Facing Reinforced Problems Facing Reinforced Concrete StructuresConcrete Structures

Load increases.Load increases.

Damage to structural parts.Damage to structural parts.

Improvements in suitability for use.Improvements in suitability for use.

Modification of structural system.Modification of structural system.

Errors in planning or construction.Errors in planning or construction.

STRENGTHENING REINFORCED STRENGTHENING REINFORCED CONCRETE STRUCTURES BY BONDING CONCRETE STRUCTURES BY BONDING STEEL PLATESSTEEL PLATES::

StrengtheningStrengthening is the process of is the process of adding capacity to a member of adding capacity to a member of structure.structure.

Attachment of steel to concrete:Attachment of steel to concrete:

1.1. Adhesive connecting mechanism. Adhesive connecting mechanism.

2.2. Bolting connecting mechanism. Bolting connecting mechanism.

Explanatory SketchExplanatory Sketch

Fig. 1 Techniques of plating reinforced concrete beams.

STRENGTHENING REINFORCED STRENGTHENING REINFORCED CONCRETE STRUCTURES BY CONCRETE STRUCTURES BY PRESTRESSING CABLESPRESTRESSING CABLES::

Post-tensioningPost-tensioning is a technique is a technique used to prestress reinforced concrete used to prestress reinforced concrete after concrete is placed.after concrete is placed.

The tensioning provides the member The tensioning provides the member with an immediate and active load-with an immediate and active load-carrying capability.carrying capability.

External Post-tensioned pictureExternal Post-tensioned picture

The advantages of External The advantages of External PrestressingPrestressing

Ability to restress, destress and Ability to restress, destress and exchange any external prestressing exchange any external prestressing cable.cable.

Crack free members.Crack free members. Reduce deflection.Reduce deflection. High fatigue and impact resistance.High fatigue and impact resistance.

The Disadvantages of External The Disadvantages of External PrestressingPrestressing

Usually requiring a greater section Usually requiring a greater section depth. depth.

More exposed to environmental More exposed to environmental influences (fire, vandalism, influences (fire, vandalism, aggressive chemicals etc.).aggressive chemicals etc.).

Handling of the tensioning devices Handling of the tensioning devices may be more difficult.may be more difficult.

High cost.High cost.

Concrete JacketsConcrete Jackets(Section Enlargement)(Section Enlargement)

Concrete Jackets Concrete Jackets (Section Enlargement)(Section Enlargement)

Enlargement is the Enlargement is the placement of additional placement of additional concrete and reinforcing concrete and reinforcing steel on an existing steel on an existing structural member.structural member.

Beams, slabs, columns, Beams, slabs, columns, and walls, if necessary, and walls, if necessary, can be enlarged to add can be enlarged to add stiffness or load-carrying stiffness or load-carrying capacity.capacity.

Concrete JacketsConcrete Jackets

In most cases, the In most cases, the enlargement must be enlargement must be bonded to the existing bonded to the existing concrete to create a concrete to create a monolithic member for monolithic member for additional shear or additional shear or flexural capacity.flexural capacity.

Column Compressive strengthening by Column Compressive strengthening by Section EnlargementSection Enlargement

•Enlarging the cross section of an existing column will strengthen the column by increasing its load carrying capacity. •A column can be enlarged in various configurations. •The drying shrinkage effects in the concrete used to enlarge the column must be considered.

Section EnlargementSection EnlargementMethod AMethod 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.

Section EnlargementSection EnlargementMethod AMethod A

•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.

Section EnlargementSection EnlargementMethods B & CMethods 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.

Disadvantages of the concrete Disadvantages of the concrete jacketsjackets

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

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

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

Fiber Reinforced Fiber Reinforced PolymerPolymer

Fiber Reinforced Polymer Fiber Reinforced Polymer (FRP)(FRP)

FRP is a new class of composite FRP is a new class of composite material for the development and material for the development and repair of new and deteriorating repair of new and deteriorating structures in Civil Engineering. structures in Civil Engineering.

Search for alternatives to Steel and Search for alternatives to Steel and alloys to combat the high costs of alloys to combat the high costs of repair and maintenance of structures repair and maintenance of structures damaged by corrosion and heavy use.damaged by corrosion and heavy use.

FRP Laminate StructureFRP Laminate Structure

• FRPs are organized in a laminate FRPs are organized in a laminate structure.structure.

• each lamina (flat layer) contains an each lamina (flat layer) contains an arrangement of unidirectional fibers arrangement of unidirectional fibers fabrics embedded within a thin layer fabrics embedded within a thin layer of light polymer matrix material.of light polymer matrix material.

FRP consists of two main FRP consists of two main components:components:1.1. Fibers.Fibers.2.2. Resin or Matrix.Resin or Matrix.

FRP Laminate StructureFRP Laminate Structure

Types of FRPTypes of FRP

The three main types of fibers used The three main types of fibers used are: are: • Carbon.Carbon.• Glass.Glass.• Aramid.Aramid.

Suitability of FRP for Uses in Suitability of FRP for Uses in Structural EngineeringStructural Engineering

FRP properties and advantages makes it FRP properties and advantages makes it ideal for wide spread applications in ideal for wide spread applications in construction worldwide.construction worldwide.

FRP has a few disadvantages.FRP has a few disadvantages.

Advantages of FRPAdvantages of FRP::

Corrosion Resistance.Corrosion Resistance. Lightweight.Lightweight. Ease of installation.Ease of installation. Less Finishing.Less Finishing. Less maintenance.Less maintenance. Ductility of FRP wrapped members Ductility of FRP wrapped members

improves dramatically.improves dramatically. They are ideal for external application.They are ideal for external application.

Advantages of FRPAdvantages of FRP

They are extremely durable.They are extremely durable. They are available in various They are available in various

forms: sheets, plates, fabric, etc.forms: sheets, plates, fabric, etc. They are available in long lengths They are available in long lengths

that eliminates joints and splices.that eliminates joints and splices. They cure within 24 hours.They cure within 24 hours. Versatility.Versatility. Anti-seismic behavior.Anti-seismic behavior.

Disadvantages of FRPDisadvantages of FRP

High cost, susceptibility to High cost, susceptibility to deformation under long-term loads deformation under long-term loads

Temperature and moisture effects, Temperature and moisture effects, lack of design codes, and most lack of design codes, and most importantly, lack of awareness.importantly, lack of awareness.

DecisionDecision

Steel platesSteel platesConcrete Concrete jacketingjacketing

FRPFRP

High CorrosionHigh CorrosionMedium CorrosionMedium CorrosionCorrosion resistanceCorrosion resistance

Low CostLow CostHigh CostHigh CostHigh CostHigh Cost

High Installation High Installation costcost

High Installation costHigh Installation costEase of installationEase of installation..

more Maintenancemore Maintenancemore Maintenancemore MaintenanceLess MaintenanceLess Maintenance

Heavy WeightHeavy WeightHeavy WeightHeavy Weightlight Weightlight Weight

IntroductionIntroduction

M.S.Project gantt chart.M.S.Project gantt chart. Lab tests on FRP material.Lab tests on FRP material. Cost estimation for G.P.1Cost estimation for G.P.1

M.S. Project Gantt ChartM.S. Project Gantt Chart

Experimental lab test on FRP Experimental lab test on FRP material.material.

The main objective of this experiment The main objective of this experiment was to study the effect of different was to study the effect of different environments on the behavior of FRP environments on the behavior of FRP material. material.

Beams DetailsBeams Details This experiment consists of 16 beams and 6 cubes.This experiment consists of 16 beams and 6 cubes. Beams were divided to 4 groups, each group consists Beams were divided to 4 groups, each group consists

of 4 beams with four different reinforcements.of 4 beams with four different reinforcements. Beams dimensions were 10cm x 10cm x 50cm.Beams dimensions were 10cm x 10cm x 50cm. Minimum reinforcement of one bar with 6mm Minimum reinforcement of one bar with 6mm

diameter (1diameter (1ΦΦ6) was used.6) was used.

Groups EnvironmentGroups EnvironmentEach group was exposed to four different Each group was exposed to four different

environments as follows:environments as follows:

Group 1:Group 1: Room temperature with 26Room temperature with 26ooC.C.Group 2:Group 2: Hot water tank with 100 % humidity at 45Hot water tank with 100 % humidity at 45ooC.C.Group 3:Group 3: Oven (0% humidity) at 45Oven (0% humidity) at 45ooC.C.Group 4:Group 4: Outside exposed to sun radiation and the Outside exposed to sun radiation and the

variation in temperature through the 24 variation in temperature through the 24 hours. hours.

Digital balance.Digital balance. Molds of beams and cubes.Molds of beams and cubes. Mixer.Mixer. Vibrator.Vibrator. Hot water tank.Hot water tank. Oven.Oven. Cube test machine.Cube test machine. Beam test machine.Beam test machine.

EquipmentsEquipments

MaterialsMaterials

Concrete mix: water, Concrete mix: water, cement, sand, coarse cement, sand, coarse and small aggregates.and small aggregates.

Plastic sheet.Plastic sheet. FRP strips.FRP strips. Strain gages.Strain gages.

ProceduresProcedures Steel reinforcements were Steel reinforcements were

prepared.prepared. Strain gages were fixed on the Strain gages were fixed on the

steel reinforcement.steel reinforcement. Concrete ingredients were Concrete ingredients were

calculated, weighted and calculated, weighted and mixed using a big mixer.mixed using a big mixer.

Concrete was poured in the Concrete was poured in the molds of beams and cubes.molds of beams and cubes.

Concrete was vibrated and Concrete was vibrated and covered by plastic sheet.covered by plastic sheet.

ProceduresProcedures

3 cubes were tested after 7 days.3 cubes were tested after 7 days. Concrete beams and cubes were Concrete beams and cubes were

removed from molds and cured in removed from molds and cured in potable water for 14 days.potable water for 14 days.

Beams and cubes were exposed to Beams and cubes were exposed to air drying in laboratory.air drying in laboratory.

ProceduresProcedures

FRP was applied with FRP was applied with layer of epoxy.layer of epoxy.

Beams were exposed to Beams were exposed to the different the different environments for 1000 environments for 1000 hours.hours.

3 cubes was tested after 3 cubes was tested after 28 days.28 days.

All beams was tested All beams was tested after 1000 hoursafter 1000 hours..

Experimental ResultExperimental Result

Experimental ResultsExperimental Results

Experimental ObservationsExperimental Observations

1.1. Effect of Fiber Reinforcement Polymer Effect of Fiber Reinforcement Polymer (FRP) on strengthening the beams:(FRP) on strengthening the beams:

One FRP strip increased the beam's capacity One FRP strip increased the beam's capacity by about 100% for all environments.by about 100% for all environments.

Two strips of FRP increased the beam's Two strips of FRP increased the beam's capacity by about 200% for all environments.capacity by about 200% for all environments.

All reinforced beams strengthen with FRP All reinforced beams strengthen with FRP failed on de-bonding of the FRP at the end of failed on de-bonding of the FRP at the end of strips due to the shear force at this location.strips due to the shear force at this location.


2.2. Environmental effect on the Environmental effect on the beams:beams:

The effect of environment on reinforced The effect of environment on reinforced concrete beams with steel only is concrete beams with steel only is negligible. negligible.

Plain concrete with one strip of FRPPlain concrete with one strip of FRP (shear force) was affected in hot (shear force) was affected in hot environments (humid and dry). Where environments (humid and dry). Where the effect of outdoor and indoor the effect of outdoor and indoor environments was negligible.environments was negligible.


The reinforced concrete beams strengthen The reinforced concrete beams strengthen with FRP; with FRP; ((bond capacity between the bond capacity between the FRP and the concreteFRP and the concrete)) was affected in was affected in hot hot and humid environment.and humid environment.

Although the FRP in the outdoor Although the FRP in the outdoor environment was subjected to the Ultra environment was subjected to the Ultra Violet during the 1000 hrs exposure, no Violet during the 1000 hrs exposure, no reduction in the beam capacity was reduction in the beam capacity was noticed.noticed.

Cost Estimation

Total Cost = 1496 Dhs (within the budget)

Item #Item DescriptionManufacturersCost/ unit

# unitsTotal Cost Dhs

15MM Steel Strain Gages Single INSTALLATION middle east

2525625

2Super Glue 5g BottleINSTALLATION middle east

22244

3Fiber Reinforcement Polymer strips (Sika Carbodur S type)

Sika Company75 Dhs/m

7 m525

4FRP Epoxy (Sikadur 30 normal)(6kg)

Sika Company256150

5Reinforcement Steel Bars (#6)Al-Moazam stores21224

6Drawings Copying41768

7Reinforcement Steel Welding5/beam1260

Analysis backgroundAnalysis background

The most important and most The most important and most difficult task faced by the structural difficult task faced by the structural designer is the accurate estimation designer is the accurate estimation of the loads that may be applied to of the loads that may be applied to the structure during its life.the structure during its life.

The next problem is to decide the The next problem is to decide the worst possible combinations of these worst possible combinations of these loads that might occur at one time. loads that might occur at one time.


The loads that will be used in this The loads that will be used in this project are dead and live loads. project are dead and live loads.

Dead loads are loads of constant Dead loads are loads of constant magnitude that remain in one magnitude that remain in one position. position.

Live loads are loads that can change Live loads are loads that can change in magnitude and position. in magnitude and position.


ACI code (9.2) states that the ACI code (9.2) states that the required ultimate load carrying required ultimate load carrying ability of the member U provided to ability of the member U provided to resist the dead load D and the live resist the dead load D and the live load L must at least equal:load L must at least equal:

U = 1.4D + 1.7LU = 1.4D + 1.7L


The Loads carried by the structure are The Loads carried by the structure are transferred from one structural element to transferred from one structural element to another until it reaches its final destination another until it reaches its final destination to the supporting ground.to the supporting ground.

The loads that come from slabs to beams The loads that come from slabs to beams can be estimated according to the slabs can be estimated according to the slabs design system and the geometry of these design system and the geometry of these slabs. slabs.


In one direction slabs the beam is In one direction slabs the beam is carrying half of the slab as a carrying half of the slab as a rectangular or square shape.rectangular or square shape.

In two way slabs the each beam In two way slabs the each beam around the slab is carrying triangle or around the slab is carrying triangle or trapezoidal shape of the slab.trapezoidal shape of the slab.

Prokon Structural Analysis & DesignProkon Structural Analysis & Design

Prokon structural analysis and design Prokon structural analysis and design is a useful tool for analysis and is a useful tool for analysis and design of structures.design of structures.

The PROKON suite has two main The PROKON suite has two main components:components:

PROKON Calcpad.PROKON Calcpad. PROKON analysis and design PROKON analysis and design

modules . modules .


PROKON interface. PROKON interface.


Input parameters.Input parameters.


Section dimensions. Section dimensions.


Spans lengths. Spans lengths.


Input loads.Input loads.


Shear and Moment diagramsShear and Moment diagrams..

Structural system of the buildingStructural system of the building

Area = 750 mArea = 750 m22.. It consists of two stories.It consists of two stories. Types of slabs: One way Hurdy slabs, Types of slabs: One way Hurdy slabs,

two way hurdy slabs and two way two way hurdy slabs and two way solid slabs. solid slabs.

Types of columns: Rectangular and Types of columns: Rectangular and circular.circular.

There are projected beams and There are projected beams and hidden beams. hidden beams.

Structural system of the buildingStructural system of the building

The Floor cover = 2 KN/mThe Floor cover = 2 KN/m22.. The Live load = 2 KN/mThe Live load = 2 KN/m22..

Hurdy slab load Hurdy slab load

The unfactored loads calculation of The unfactored loads calculation of the one way Hurdy slabs. the one way Hurdy slabs.

Comparison between hand & Comparison between hand & Prokon resultsProkon results

Hand results:Hand results:

m

KNweightWall

m

KNmm

m

KNWeightSelf

75.5

48.02.0253

KNlWu

Vu

mKNlWu

Mu

m

KN

m

KN

m

KNWu

5.352

2.565.13

2

.137.468

)2.5(65.13

8

)(

65.13)475.5(4.1

22

Comparison between hand results Comparison between hand results and Prokon resultsand Prokon results

PROKON results:PROKON results:

ConclusionConclusion

It was learned some modern It was learned some modern technologies in strengthening technologies in strengthening concrete structures.concrete structures.

It was learned a new computer It was learned a new computer software program.software program.

The a knowledge that we gained The a knowledge that we gained from structural analysis and design from structural analysis and design courses were applied. courses were applied.

ConclusionConclusion

From the experimental results, it was From the experimental results, it was found that the FRP was effected by found that the FRP was effected by 20 % in the hot (0% humidity) 20 % in the hot (0% humidity) environment.environment.

It was decided to use FRP to strength It was decided to use FRP to strength the building.the building.

It was learned how to analyze one It was learned how to analyze one way Hurdy slabs and beams. way Hurdy slabs and beams.

Thank YouThank Youfor Listening for Listening