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MASTER OF SCIENCEIn Civil Engineering

THE EFFECT OF CREATED OPENING UNDER WORKING LOAD ON BEHAVIOR OF R.C BEAMS

ByEng. Michael Mabrouk Abd Elnaeem Zaki

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Supervisors

Assoc. Prof. Dr. Mustafa Osman Abd ElmigeedAssociate Professor of Civil Engineering Faculty of Engineering Al-MatariaHelwan University

Assoc. Prof. Dr.Ata El Kareim Shoeib

Associate Professor of Civil EngineeringFaculty of Engineering Al-MatariaHelwan UniversityDr. Magdy Mahmoud GenidiLecturer of Civil EngineeringFaculty of Engineering Al-MatariaHelwan University2

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THESIS OUTLINES Introduction Objectives Experimental program Results and analysis Conclusions

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INTRODUCTION

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INTRODUCTIONOpening uses and shapesShear studyOpening in shear zoneBehavior of beam with openingStrengthening of openingFRP uses and advantages

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Opening uses

Openings are usually found in floors due to staircase, ducts and pipes. Openings are provided through beam web to facilitate the passage of utility pipes and service ducts. These service ducts accommodate essential services such as conduits, power supply, water and drainage pipes, ventilation system, air-conditioning and network system access or even for inspection purposes in beam structures.

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Different shapes of opening9

Shear study10

1.At load transfer2.At service load stage

Opening in beam in shear zone

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Opening in beam in shear zone12

Opening in beam in shear zone with different locations13

However, the presence of opening in the web of a reinforced concrete beam resulted to many problems in the beam behavior including reduction in beam stiffness, excessive cracking and deflection and reduction in beam capacity. Furthermore, inclusion of openings leads to high stress concentration around the openings especially at the opening corners.

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Opening Effect

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Strengthening of opening16

In general, shear failure of concrete structures is catastrophic due to the brittle nature and the fact of no advance warning prior to failure. Thus, in an existing beam, strengthening externally around the opening is crucial with the use of external reinforcing material, such as steel plates or by Fiber Reinforced Polymer materials.

Different uses of FRP17

Advantages of using FRP in opening strength18

Research Objectives

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Research Objectives

The time of creating opening before cast OR after cast The behavior of beam with opening Size effect Strengthening materials used in opening strength 20

Experimental program21

Experimental program Test Parameters The test setup A detailed description of specimens The test procedure.

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The main test parameters are:-Types of opening Small opening or Large opening

Types of strengthening material GFRP or CFRP or Steel plates

Time of creating of opening Existed opening or Opening created after cast Test Parameters23

The test setup

No.Description1Specimen2Lever3Concrete beam load (Load 1) 4Nuts for addition load(Load 2) 5Load cell 16Load cell 27Supporting frame8Cross beam9Bracing10Anchors

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A detailed description specimens

11 beams specimens were divided into 5 groups. All specimens was casted at the same time to predict the behavior beams with variables conditions.

11 beams specimens were divided into 1 solid beam, 5 beams with small opening and 5 beams with large opening.

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All 11 RC simple beams were tested to failure under two points loading to investigate the structural behavior including crack patterns, failure mode, failure load and load-deflection relation.

1 solid control beam.2 beams with existed opening.2 beams with opening created after casting.6 beams with opening was strengthened by FRP laminates and steel plates.

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GroupNo.SpecimenNo.Strengthen materialOpening dimensions(mm)Opening location(mm)Opening casesIB1------------------------B2------120X360250Existed opening B3------120X120250IIB4------120X360250Created after casting under loadB5------120X120250

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GroupNo.SpecimenNo.Strengthen materialOpening dimensions(mm)Opening location(mm)Opening casesIIIB6GFRP120X360250Created after casting under loadB7GFRP120X120250VIB8CFRP120X360250Created after casting under loadB9CFRP120X120250

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GroupNo.SpecimenNo.Strengthen materialOpening dimensions(mm)Opening location(mm)Opening casesVB10Steel plates120X360250Created after casting under loadB11Steel plates120X120250

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Specimen No.Images

B1

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Specimen No.Images

B2

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Specimen No.Images

B3

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Specimen No.Images

B4

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Specimen No.Images

B5

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Specimen No.ImagesB6

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Specimen No.Images

B7

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Specimen No.Images

B8

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Specimen No.Images

B9

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Specimen No.Images

B10

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Specimen No.Images

B11

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The test procedure.There were two procedures in this test 1-Existed opening :- a) Make box out before casting b) Put strain gauge in steel stirrups c) Make formwork of beam d) Ready for cast e) Curing till age 28 days f) Put dial gauges g) Start of loading test

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The test procedure.2- Opening created after casting:- a) Put strain gauge in steel stirrups b) Make formwork of beam c) Ready for cast d) Curing till age 28 days e) Put dial gauges f) Start of loading test till 18% failure load of B1 g) Create an opening by using drilling machine h) Strength opening by using FRP or Steel plates k) Resume the loading test

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Results and Analysis Test results including :-Failure loads. Crack to failure load ratioCrack pattern and Mode of failure.Theoretical results Load deflection relationship.Deflection profile of beam with opening

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Failure loads of beams with large opening.45

Failure loads of beams with small opening.46

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Failure loads of beams with opening width.47

Crack load to failure load ratio for .beam with large opening48

Crack load to failure load ratio for beam with small opening49

Failure modes and Crack patterns.

The failure modes of tested beams can be classified as follow:- Shear compression failure shear mode at large opening region Frame-type failure of small openingBrittle rupture failure of FRPLittle Brittle failure50

Theoretical results

problems will be classified into three collections according to the beam type :- a. Beam without opening.B. Beams with existed opening.C. Beams with opening created after casting.

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Theoretical results: Shear design a. Beam without opening.Shear design for beam will be solved according to ACI and ECP codes By ACI code:Vu Vn and Vn = Vc + VsVc = 0.17 'c bwd Vs = Av fy.d/ S

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Theoretical results: Shear designBy ECP code Vt = Qt.b.dQt = Vc / 2 + Vs Vc = 0.75 * (Fcu/ c) ^ 0.5 Vs = Av fy / (S.b. s)

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Theoretical results

B. Beams with existed opening.shear design for beam according to the ACI Code and ECP code for beam with opening.

then plastic hinge method simplified method 1 to make check if the section at mid opening is safe or not safe.

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Theoretical results

B. Beams with existed opening.then plastic hinge method simplified method

F'c = 0.85 * fcu Eq. (5.15)d= t- 2*c.c Eq. (5.16)Vc = bw (d do) Eq. (5.17)Vu max = 5* * Vc Eq. (5.18)

If (Vu max Vu) the section is safe, If (Vu max < Vu) the section is not safe. 55

Theoretical results

C. Beams with opening created after casting.It will be solved by plastic hinge method-simplified method 1 then strengthening will be solved by FRP shear strengthening ''U-wrap''.

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Theoretical results

C. Beams with opening created after casting.strengthening will be solved by FRP shear strengthening ''U-wrap''. (D.1) Compute the design material properties. f fu = CE* f*fu Eq. (5.23) fu = CE* *fu Eq. (5.24)(D.2) Calculate the effective strain level strain in the FRP shear reinforcement. Le = 23300 / (n * t f * E f) (0.58) Eq. (5.25)K1 = (f 'c / 27) (2/3) Eq. (5.26)K2 = (dfv - Le) / dfv Eq. (5.27)Kv = (K1* K2 * Le) / (11910 * fu) 0.75 Eq. (5.28)fe = Kv * fu 0.004 Eq. (5.29)

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Theoretical results

C. Beams with opening created after casting.strengthening will be solved by FRP shear strengthening ''U-wrap''. (D.3) Calculate the contribution of the FRP reinforcement to the shear strength.A fv = 2 * n * t f * w f Eq. (5.30)Ffe = fe * Ef Eq. (5.31)Vf = A fv * Ffe (Sin + Cos ) * d fv / Sf Eq. (5.32)(D.4) Calculate the shear strength of the section. Vn = (Vc + Vs + fVf) Eq. (5.33)In case Vn > Vu Eq. (5.34)The strengthened section is capable of sustaining the required shear strength.

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Theoretical results

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Theoretical results for small opening

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Theoretical results for large opening

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Load-Deflection relationship of beams with large opening.

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Load-Deflection relationship of beams with large opening.63

Load-Deflection relationship of beams with small opening.64

Load-Deflection relationship of beams with small opening.65

Deflection profile of beams with .large opening66

+ B6, B8 and B10 at 80% failure load

Deflection profile of beams with .small opening67

CONCLUSIONS

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CONCLUSIONSDeflection profile of beam with opening had a change of line of slope, not the normal curvature deflection in comparison of normal beam without opening.

Create an opening under load causing reduction in the stiffness of RC opening than making an opening before casting.

Create an opening can transfer the maximum deflection from mid span to mid opening approximately according to opening size and locations.

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CONCLUSIONSStrength an opening may compensate failure load of beam with opening according to opening size and type of strengthening.

Using strengthening material make a cracks control around the opening (confined zone).

Using steel plates in strengthening make beam less brittle than using GFRP or CFRP.

Using steel plates achieve the best results in opening strengthening than using GFRP or CFRP.70

CONCLUSIONSConsidering of small opening OR large opening mainly depends on behavior of beam with opening.

Deflection under opening should be considered when making deflection design for beam with opening.

The main failure mode of beam with opening was shear failure at opening region.

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CONCLUSIONSACI has the best prediction in terms of beams with small opening created after casting then strengthened.

Beams with large opening created after casting then strengthened can be designed by ECP code or Simplified method one from (CBO) book.

We can take safety factor equal 1.25 to equivalent actual results with theatrical results in case of beam with opening under load.

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Future Researches

Create an opening in beam under load and its strengthening for RC beam with T-section.

Determination of the classifications of opening according to opening location, shape and size.

The effect of creating an opening on the behavior of beam with high strength reinforced concrete and light weight concrete under load.

Using different types of strengthening around opening.

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Finally I would like to say thanks to my supervisors:

Assoc. Prof. Dr. Mustafa Osman Abd ElmigeedAssociate Professor of Civil Engineering Faculty of Engineering Al-MatariaHelwan University

Assoc. Prof. Dr.Ata El Kareim Shoeib Associate Professor of Civil EngineeringFaculty of Engineering Al-MatariaHelwan UniversityDr. Magdy Mahmoud GenidiLecturer of Civil EngineeringFaculty of Engineering Al-Mataria Helwan University

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Prof. Dr. Mohamed Alsaied EssaProfessor of Concrete Structures Faculty of Engineering - Cairo UniversityAssoc. Prof. Dr. Nasr Zenhom HassanAssociate Professor of Concrete Structures Faculty of Engineering - Helwan University

Finally I would like to say thank to my professors:

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With All my Respectto my lovely Family and Friends76

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