Struktur Beton i

117
STRUKTUR BETON I (SNI 2847-2002) OLEH : MUDJI IRMAWAN BAMBANG PISCESA

Transcript of Struktur Beton i

Page 1: Struktur Beton i

STRUKTUR BETON I(SNI 2847-2002)

OLEH :

MUDJI IRMAWANBAMBANG PISCESA

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TABLE OF CONTENTS (1)

Design Method And Strength Requirement General Principles Of Strength Design Design For Flexure Design For Flexure And Axial Load Design For Slenderness Effect Shear Torsion Shear Friction

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TABLE OF CONTENTS (2)

Bracked, Corbel And Beam Ledges Deep Flexural Members One Way Slab System Two Way Slab System Footings

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TABLE OF CONTENTS (3)

Additional : Design For Biaxial Loading Shear In Slabs Walls Structural Plain Concrete Unified Design Provision

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REFERENCES

PCA NOTES-ON ACI 318-99 SNI 2847-2002 NAWY MCGREGOR JACK C. MCCORMAC CHUKIAWANG-CHARLE S G.SALMON

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DESIGN METHOD AND STRENGTH REQUIREMENTS (1)

Design Strength >= Required Strength (U)Design Strength = Strength Reduction Factor (f)

x Nominal StrengthStrength Reduction Factor :1. Faktor yang memperhitungkan kemungkinan

terjadinya kekuatan elemen struktur dibawah kekuatan yang diinginkan akibat variasi dari material penyusunnya dan juga akibat variasi dimensinya.

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DESIGN METHOD AND STRENGTH REQUIREMENTS (2)

Strength Reduction Factor :2.Faktor yang memperhitungkan ketidak

akuratan persamaan desain (Design Equation).3.Faktor yang memperhitungkan Derajad

Daktilitas dan Keandalan yang diperlukan pada elemen yang dibebani.

4.Faktor yang memperhitungkan kepentingan dari elemen pada struktur.

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DESIGN METHOD AND STRENGTH REQUIREMENTS (3)

Nominal Strength : Kekuatan elemen strutkur atau potongan-penampang yang dihitung dengan menggunakan asumsi dan persamaan kekuatan dari metode desain kekuatan (Strength Design method) sebelum diaplikasikan Strength Reduction Factor.

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DESIGN METHOD AND STRENGTH REQUIREMENTS (4)

Required Strength (U) : Load Factor x Service Load Effect.

Load Factor : Faktor overload yang terjadi akibat kemungkinan terjadinya variasi pembebanan yang berlebih pada beban kerja (Service Load).

Service Load : Beban spesifik yang diatur oleh peraturan pembebanan (Unfactored).

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DESIGN METHOD AND STRENGTH REQUIREMENTS (5)

Notation : Required Strength (U):Mu = Factored Flexural MomentPu = Factored Axial LoadVu = Factored Shear ForceTu = Factored Torsional Moment

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DESIGN METHOD AND STRENGTH REQUIREMENTS (6)

Notation : Nominal Strength :Mn = Nominal Flexural Moment StrengthPn = Nominal Axial Load Strength At Given

Eccentricity.Vn = Nominal Shear StrengthTn = Nominal Torsional Moment Strength

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DESIGN METHOD AND STRENGTH REQUIREMENTS (7)

Notation : Nominal Strength :fMn = Design Flexural Moment StrengthfPn = Design Axial Load Strength At Given

Eccentricity.fVn = Design Shear StrengthfTn = Design Torsional Moment Strength

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DESIGN METHOD AND STRENGTH REQUIREMENTS (8)

Strength Requirement :Design Strength > Required Strength (U)Strength Reduction Factor (f) x Nominal

Strength > Load Factor x Service Load EffectExample :

f Mn > Mu f Pn > Pu f Vn > Vu

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DESIGN METHOD AND STRENGTH REQUIREMENTS (9)

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DESIGN METHOD AND STRENGTH REQUIREMENTS (10)

Nominal Strength:Mn=As.fy.(d-a/2)f.Mn=f[As.fy.(d-a/2)

Required Strength (U):Mu=1.2Md+1.6Ml

Strength Design Requirement :f.Mn>Muf[As.fy.(d-a/2)>1.2Md+1.6Ml

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DESIGN METHOD AND STRENGTH REQUIREMENTS (11)

Required Strength :U=1.4DU=1.2D+1.6LU=1.2D+1.6L+0.5(A or R)U=1.2D+1.0L+1.6W+0.5(A or R)U=0.9D+1.6WU=1.2D+1.0L+1.0EU=0.9D+1.0EU=1.4(D+F)U=1.2(D+T)+1.6L+0.5(A or R)

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DESIGN METHOD AND STRENGTH REQUIREMENTS (12)

Keterangan :D=Beban MatiL=Beban HidupA=Beban AtapR=Beban HujanW=Beban AnginE=Beban GempaT=Beban Kombinasi Rangkak,Susut Dan Perbedaan Penurunan

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DESIGN METHOD AND STRENGTH REQUIREMENTS (13)

Strength Reduction Factor (f):Flexure Without Axial Load : 0.8Axial Compression And Axial Compression W/ Flexure :Members With Spiral Reinforcement : 0.7Others Member : 0.65Shear And Torsion : 0.75

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GENERAL PRINCIPLES OF STRENGTH DESIGN (1)

Stress-Strain Curves Of Concrete

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GENERAL PRINCIPLES OF STRENGTH DESIGN (2)

Stress-Strain Reinforcement

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GENERAL PRINCIPLES OF STRENGTH DESIGN (3)

Design Assumption #1Strain in Reinforcement And Concrete Shall Be

Assumed Directly Proportional From The Neutral Axis

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GENERAL PRINCIPLES OF STRENGTH DESIGN (4)

Design Assumption #1Strain in Reinforcement And Concrete Shall Be

Assumed Directly Proportional From The Neutral Axis

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GENERAL PRINCIPLES OF STRENGTH DESIGN (5)

Design Assumption #2Maximum usable strain at extreme concrete

compression fiber shall be assumed equal to eu =0.003

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GENERAL PRINCIPLES OF STRENGTH DESIGN (6)

Design Assumption #3Stress in reinforcement fs below the yield strength fy shall be taken as Es times the steel strain es . For strains greater than fy/Es, stress in reinforcement shall be considered independent of strain and equal to fy.

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GENERAL PRINCIPLES OF STRENGTH DESIGN (7)

Design Assumption #4Tensile strength of concrete shall be neglected in

flexural calculation of reinforced concrete.

Design Assumption #5Relationship between concrete compressive stress

distribution and concrete strain shall be assumed to be rectangular, trapezoidal, parabolic, or any other

shape that results in prediction of strength in substantial agreement with results of

comprehensive tests.

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GENERAL PRINCIPLES OF STRENGTH DESIGN (8)

Design Assumption #5

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GENERAL PRINCIPLES OF STRENGTH DESIGN (9)

Design Assumption #5

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GENERAL PRINCIPLES OF STRENGTH DESIGN (10)

Design Assumption #5

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GENERAL PRINCIPLES OF STRENGTH DESIGN (11)

Design Assumption #6Parabolic Stress-

Strain distribution in concrete may be considered satisfied by an

equivalent rectangular

concrete stress distribution.

30MPa 58MPa

65.005.07

30'85.01

cf

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GENERAL PRINCIPLES OF STRENGTH DESIGN (12)

Design Assumption #6

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GENERAL PRINCIPLES OF STRENGTH DESIGN (13)

Design Assumption #6

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GENERAL PRINCIPLES OF STRENGTH DESIGN (14)

Dalam menganalisa struktur beton bertulang ada tiga kondisi kegagalan yang harus diketahui :•Balanced Strain ConditionKondisi dimana kegagalan elemen struktur terjadi pada saat beton serat terluar tertekan mengalami kehancuran bersamaan dengan terjadinya leleh pada tulangan baja tarik terluar.•Over-Reinforced ConditionKondisi dimana kegagalan elemen struktur terjadi pada saat beton serat terluar tertekan mengalami kehancuran tetapi leleh belum terjadi pada tulangan tarik terluar. (Getas)

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GENERAL PRINCIPLES OF STRENGTH DESIGN (15)

Dalam menganalisa struktur beton bertulang ada tiga kondisi kegagalan yang harus diketahui :•Under-Reinforced ConditionKondisi dimana kegagalan elemen struktur terjadi pada saat tulangan tarik terluar mengalami pelelehan tetapi beton pada serat tertekan paling luar belum mengalami kegagalan. (Daktail)

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GENERAL PRINCIPLES OF STRENGTH DESIGN (16)

Balanced Strain Condition

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GENERAL PRINCIPLES OF STRENGTH DESIGN (17)

Balanced Strain Condition

fyfy

600

600

200000/003.0

003.0

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GENERAL PRINCIPLES OF STRENGTH DESIGN (18)

Balanced Strain Condition

fyfy

f c

600

60085.0 '1

Untuk menjamin sebuah struktur berada dalam kondisi under reinforced maka :

fyfy

f cbal 600

60085.075.075.0 '1

max

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GENERAL PRINCIPLES OF STRENGTH DESIGN (19)

Minimum Reinforcement Of Flexural Member

dbf

dbf

fA w

yw

y

cs

4.13 'min

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GENERAL PRINCIPLES OF STRENGTH DESIGN (20)

Stress Strain Diagram In 3 Condition :

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DESIGN FOR FLEXURE (1)

Single Reinforced Concrete Beam

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DESIGN FOR FLEXURE (2)

Force Equilibrium :

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DESIGN FOR FLEXURE (3)

Moment Equilibrium :

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DESIGN FOR FLEXURE (4)

A nominal strength coefficient of resistance Rn is obtained when both sides of Eq. (2) are divided by bd2:

When b and d are preset, r is obtained by solving the quadratic equation for Rn:

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DESIGN FOR FLEXURE (5)

Equation (3) can be used to determine the steel ratio r given Mu or vice-versa if the section properties b and dare known. Substituting Mn = Mu/f into Eq. (3) and dividing each side by fc :

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DESIGN FOR FLEXURE (6)

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DESIGN FOR FLEXURE (7)

Graphics Rn Vs r

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DESIGN FOR FLEXURE (8)

Example 1 (Analyzing) :Calculate the Moment Nominal of The Concrete Section :

d=350mm

h=400mm

b=250mm

cover=50mm

3D19

Mutu Beton (f’c) : 35 MPaMutu Baja (f’c) : 400 MPa

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DESIGN FOR FLEXURE (9)

Example 1 (Analyzing) :22 8501925.03 mmAs

mmbf

fAa

c

ys 71.452503585.0

400850

85.0 '

kNmM

M

adfAM

n

n

ysn

229.111

2

71.45350400850

2

T

C

d

a

d-a/2

Page 48: Struktur Beton i

DESIGN FOR FLEXURE (10)

Example 2 (Design) :Design the concrete section of the beam, which is simple supported and were loaded as below :

L=6m

Ql=1.5t/m;Qd=1t/m

kNmMMM

kNmtmlqM

kNmtmlqM

ldu

ll

dd

76.15815.666.11.442.16.12.1

15.6675.665.18

1

8

1

1.445.4618

1

8

1

22

22

Spesification :Mutu Beton (f’c)=35 MPaMutu Baja (fy)=400 MPa

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DESIGN FOR FLEXURE (11)

Example 2 (Design) :#1 Determine maximum reinforcement ratio (rmax) for material strength f’c=35MPa And fy=400MPa :

65.0814.01

65.005.07

303585.01

65.005.07

30'85.01

cf

0272.0

400600

600

400

35814.085.075.0

600

60085.075.075.0

max

max

'1max

fyfy

f cbal

Calculating b1

Calculating rmax :

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DESIGN FOR FLEXURE (12)

Example 2 (Design) :#2 Compute bd2 required :

32

'22

23008696625.88.0

100000076.158

625.83585.0

4000272.05.014000272.0

85.0

5.01

mmR

Mbd

MPaR

f

ff

bd

M

bd

MR

n

u

n

c

yy

unn

Page 51: Struktur Beton i

DESIGN FOR FLEXURE (13)

Example 2 (Design) :#3 Size member so that bd2 > bd2 required :

mmd

mmb

37.303250

23008696

250

Minimum Beam Depth (h) = d + cover Minimum Beam Depth (h) = 303.37 + 50 = 353.37 mmUse minimum Beam Depth (h) = 400 mmTherefore :d = h – cover = 400 – 50 = 350 mm

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DESIGN FOR FLEXURE (14)

Example 2 (Design) :#4 Using the 400 mm. beam depth, compute a revised value of r :

MPabd

MR

bd

MR

un

un

48.63502508.0

100000076.15822

2

0035.00185.00272.0

400

4.14.1

3585.0

48.6211

400

3585.00272.0

4.1

85.0

211

85.0

minmax

minmax

min'

'max

fy

fyf

R

f

f

c

n

y

c

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DESIGN FOR FLEXURE (15)

Example 2 (Design) :#5 Compute As Required :As = r x b x dAs = 0.0185 x 250 x 350As = 1618.75 mm2Pakai 6 D19 (As=1701 mm2)

#6 CrossCheck The Moment Nominal with Moment Ultimate :

kNmMkNmM

kNma

dfAM

nu

ysn

071.17876.158

071.1782

71.4535040017018.0

2

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DESIGN FOR FLEXURE (16)

Example 2 (Design) :#7 Ilustrated The Section With Reinforcement :

d=350mm

b=250mm

h=400mm

cover=50mm

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DESIGN FOR FLEXURE (17)

Concrete Section With Compression Reinforcement

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DESIGN FOR FLEXURE (18)

Concrete Section With Compression Reinforcement

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DESIGN FOR FLEXURE (19)

Concrete Section With Compression Reinforcement

2'

'85.0

1

'

1

adfAAM

fAAabf

TC

yssn

yssc

c

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DESIGN FOR FLEXURE (20)

Concrete Section With Compression Reinforcement

''

''

'

'

2

2

2

ddfAM

or

ddfAM

fAfA

TC

ysn

ssn

yssss

s

Page 59: Struktur Beton i

DESIGN FOR FLEXURE (20)

Concrete Section With Compression Reinforcement

''2

'

21

ddfAa

dfAAM

MMM

ssyssn

nnn

21

'

TTT

CCC

TC

sc

Force Equilibrium :

Solving The Force Equilibrium We Achieved That :

bf

fAAa

bf

fAfAa

c

yss

c

ssys

'' 85.0

';

85.0

'

Page 60: Struktur Beton i

DESIGN FOR FLEXURE (21)

Design Procedure :#1 Calculate c < 0.75 cb :

dfy

cc b 600

60075.075.0

#2 Calculate As1 with c determined from above :

y

cs f

cbfA '185.0

#3 Calculate Mn1 :

21

adfAM ysn

Page 61: Struktur Beton i

DESIGN FOR FLEXURE (22)

Design Procedure :#4 Calculate Mn-Mn1 :

#5 If Compression Reinforcement is Required Then Calculate T2 :

#6 Control The Yield Of Compression Reinforcement :

0

0

1

1

nn

nn

MM

MM (Compression Reinforcement Is Required)

(Compression Reinforcement Is Not Required)

'' 12 dd

MMTC nn

s

fyc

dfs

fyc

dfs

600'

1

600'

1 (Compression Reinforcement Yield)

(Compression Reinforcement Not Yield)

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DESIGN FOR FLEXURE (23)

Design Procedure :#7 Calculate The Required Compression Reinforcement :

#8 Calculate The Additional Tension Reinforcement :

#9 Calculate Required Reinforcement :As = As1 + AssAs’ = As’

#10 Check Required Strength :fMn > Mu

cs

ss ff

CA

'85.0'

''

yss f

TA 2

Page 63: Struktur Beton i

DESIGN FOR FLEXURE (24)

Example 3 (Design) :Design the concrete section below if the factored moment applied to the concrete section is 300 kNm (Mu) :

d=550mm

h=600mm

b=300mm

cover=50mm

Mutu Beton (f’c) : 35 MPaMutu Baja (f’c) : 400 MPa

cover=50mm

Page 64: Struktur Beton i

DESIGN FOR FLEXURE (25)

Example 3 (Design) :#1 Calculate c < 0.75 cb :

mmdfy

cc b 5.247550400600

60075.0

600

60075.075.0

#2 Calculate As1 with c determined from above c=85mm:

2' 1543400

3008535814.085.085.0mm

f

cbfA

y

cs

#3 Calculate Mn1 :

kNmM n 134.3182

85813.055040015431

Page 65: Struktur Beton i

DESIGN FOR FLEXURE (26)

Example 3 (Design) :#4 Calculate Mn-Mn1 :

#5 If Compression Reinforcement is Required Then Calculate T2 :

#6 Control The Yield Of Compression Reinforcement :

0686.56314.3188.0

3001 kNmM

Mn

u

Ndd

MMTC nn

s 113372500

1000000686.56

'' 1

2

MPafyMPafs 40024760085

501

(Compression Reinforcement Not Yield)

(Compression Reinforcement Is Required)

Page 66: Struktur Beton i

DESIGN FOR FLEXURE (27)

Example 3 (Design) :#7 Calculate The Required Compression Reinforcement :

#8 Calculate The Additional Tension Reinforcement :

#9 Calculate Required Reinforcement :As = 1543 + 283 = 1826 mm2 ( 7 D 19 = 1988 mm2)As’ = 521 mm2 (2 D 19 = 568 mm2)

2

'

5213585.0247

113372

85.0'

'' mm

ff

CA

cs

ss

22 283400

113372mm

f

TA

yss

Page 67: Struktur Beton i

DESIGN FOR FLEXURE (28)

Example 3 (Design) :#10 Check The Moment Required :

kNmMkNmM

M

ddfAa

dfAfAM

un

n

ssssysn

300325148.70190.3378.0

505502475682

26.7055024756840019888.0

''2

'

mmbf

fAfAa

c

ssys 378.733003585.0

2475684001988

85.0

'

'

Page 68: Struktur Beton i

DESIGN FOR FLEXURE (29)

Example 3 (Design) :Design the concrete section below if the factored moment applied to the concrete section is 300 kNm (Mu) :

d=550mm

h=600mm

b=300mm

cover=50mm

Mutu Beton (f’c) : 35 MPaMutu Baja (f’c) : 400 MPa

cover=50mm

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DESIGN FOR FLEXURE (30)

T-Beam Concrete Section

bw

hd

beff

hf

Page 70: Struktur Beton i

DESIGN FOR FLEXURE (31)

T-Beam Concrete Section

bw 2bo bw bw2bo

beff beff beff

hf

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DESIGN FOR FLEXURE (32)

T-Beam Concrete Section

Lo

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DESIGN FOR FLEXURE (33)

T-Beam Concrete Section

No Effective Width

Spandrel Center T-Beam

1 beff < bw + 1/12 Lo beff < 1/4 Lo

2 beff < bw + 6 hf beff < bw + 16 hf

3 beff < bw + bo beff < bw + 2bo

Single T-Beam

1 beff < 4 bw

2 Flange Thickness (hf) > 1/2 bw

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DESIGN FOR FLEXURE (34)

T-Beam Concrete Section Neutral Axis x < hf

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DESIGN FOR FLEXURE (35)

T-Beam Concrete Section Neutral Axis x < hf

abfC effc '85.0

ys fAT

Force Equilibrium :

effc

ys

bf

fAa

'85.0

2

adfAM ysn

Page 75: Struktur Beton i

DESIGN FOR FLEXURE (36)

T-Beam Concrete Section Neutral Axis x > hf

Page 76: Struktur Beton i

DESIGN FOR FLEXURE (37)

T-Beam Concrete Section Neutral Axis x > hf

fweffc hbbfC '2 85.0

ys fAT

Force Equilibrium :

feff

e

wc

ys hb

b

bf

fAa

1'85.0

22 21f

n

hdC

adCM

abfC wc '1 85.0

Page 77: Struktur Beton i

DESIGN FOR FLEXURE (38)

T-Beam Concrete Section (Example 1) Analyze Mn :

bw=300mm

d=510mm

beff

hf=120mm

h=600mm

Specification :f’c = 40 MPafy = 400 MpaLo = 6000 mmBo = 2000 mm

10 D19

Page 78: Struktur Beton i

DESIGN FOR FLEXURE (39)

T-Beam Concrete Section (Example 1) :#1 Calculate Beff Of T-Beam :

mmbbb

mmhbb

mmLb

oweff

fweff

oeff

4300200023002

22201201630016

1500600025.04

1

Diambil beff = 1500 mm

Page 79: Struktur Beton i

DESIGN FOR FLEXURE (40)

T-Beam Concrete Section (Example 1) :#2 Calculate a Of T-Beam :

mmhfmmbf

fyAsa

effc

120235.2215004085.0

4002835

'85.0

kNmM

adfAM

n

ysn

565

2

235.225104002835

2

#3 Calculate Mn Of T-Beam :

Page 80: Struktur Beton i

DESIGN FOR FLEXURE (41)

T-Beam Concrete Section (Example 2) Analyze Mn :

bw=300mm

d=510mm

beff

hf=120mm

h=600mm

Specification :f’c = 20 MPafy = 500 MpaLo = 4000 mmBo = 2000 mm

10 D25

Page 81: Struktur Beton i

DESIGN FOR FLEXURE (42)

T-Beam Concrete Section (Example 2) :#1 Calculate beff Of T-Beam :

mmbbb

mmhbb

mmLb

oweff

fweff

oeff

4300200023002

22201201630016

1000400025.04

1

Diambil beff = 1000 mm

Page 82: Struktur Beton i

DESIGN FOR FLEXURE (43)

T-Beam Concrete Section (Example 2) :#2 Calculate a Of T-Beam :

mmhfmmbf

fyAsa

effc

120375.14410002085.0

5004908

'85.0

mmb

b

bf

fyAsa

eff

e

wc

76.2011300

1000

3002085.0

50049081

'85.0

Page 83: Struktur Beton i

DESIGN FOR FLEXURE (44)

T-Beam Concrete Section (Example 2) :#3 Calculate Mn Of T-Beam :

kNmM

M

adC

hdCM

kNabfC

kNhbbfC

hdC

adCM

n

n

fn

wc

fweffc

fn

57.106397.4206.642

2

76.2015101028

2

1205101428

22

102876.2013002085.085.02

142812030010002085.085.01

22

21

'

'

21

Page 84: Struktur Beton i

DESIGN FOR FLEXURE (45)

T-Beam Concrete Section (Example 3) Analyze Mn :

bw=300mm

d=510mm

beff

hf=120mm

h=600mm

Specification :f’c = 40 MPafy = 400 MpaLo = 6000 mmBo = 2000 mm

10 D19

d’=20mm

5 D19

Page 85: Struktur Beton i

DESIGN FOR FLEXURE (46)

T-Beam Concrete Section (Example 3) :#1 Calculate Beff Of T-Beam :

mmbbb

mmhbb

mmLb

oweff

fweff

oeff

4300200023002

22201201630016

1500600025.04

1

Diambil beff = 1500 mm

Page 86: Struktur Beton i

DESIGN FOR FLEXURE (47)

T-Beam Concrete Section (Example 3) :#2 Calculate a Of T-Beam with assumption that compression and tension steel yield :

'12.11

15004085.0

40014172835

'85.0

'dhmm

bf

fAAa f

effc

yss

Therefore the first assumption that the compression steel is yield is not true because a < d’, this means that the compression steel is tension steel. Analyzing the beam using single reinforced concrete :

'235.2215004085.0

4002835

'85.0dhfmm

bf

fyAsa

effc

Page 87: Struktur Beton i

DESIGN FOR FLEXURE (48)

T-Beam Concrete Section (Example 3) :From the calculation before a < hf and a > d’ this means that actualy the top reinforcement is in compression but not yielding. #3 Calculate the stress in compression reinforcement :

65.0778.0

65.005.07

304085.0

65.005.07

3085.0

1

1

'1

cf

mma

x 57.28778.0

235.22

1

Page 88: Struktur Beton i

DESIGN FOR FLEXURE (49)

T-Beam Concrete Section (Example 3) :#3 Calculate the stress in compression reinforcement :

MPax

dfs 978.179600

57.28

201600

'1'

mm

bf

fAfAa

effc

ssys 23.1715004085.0

99.17914174002835

'85.0

'

#4 Calculate the new value of a :

kNmM

M

ddfAa

dfAfAM

n

n

ssssysn

5678215.12639.441

2

205101791417

2

23.1751017914174002835

''2

'

Page 89: Struktur Beton i

DESIGN FOR FLEXURE (50)

T-Beam Concrete Section (Example 4) Analyze Mn :

bw=300mm

d=510mm

beff

hf=100mm

h=600mm

Specification :f’c = 20 MPafy = 500 MpaLo = 4000 mmBo = 2000 mm

10 D25

5 D19

Page 90: Struktur Beton i

DESIGN FOR FLEXURE (51)

T-Beam Concrete Section (Example 4) :#1 Calculate beff Of T-Beam :

mmbbb

mmhbb

mmLb

oweff

fweff

oeff

4300200023002

22201201630016

1000400025.04

1

Diambil beff = 1000 mm

Page 91: Struktur Beton i

DESIGN FOR FLEXURE (52)

T-Beam Concrete Section (Example 4) :#2 Calculate a Of T-Beam with assumption that compression and tension steel yield :

'103

10002085.0

50014174908

'85.0

'dhmm

bf

fAAa f

effc

yss

Therefore the first assumption that the compression steel is yield is might be true because a > d’, #3 Calculate the stress in compression reinforcement :85.01

mma

x 176.12185.0

103

1

MPafyMPax

dfs 50097.500600

176.121

201600

'1'

Page 92: Struktur Beton i

DESIGN FOR FLEXURE (53)

T-Beam Concrete Section (Example 4) :#4 Since the compression steel is yielding therefore the first assumption is right, therefore the a value before is used :

kNmM

M

ddfAa

dfAfAM

n

n

ssssysn

69,113825.35444.784

2

205105001417

2

176.12151050014175004908

''2

'

Page 93: Struktur Beton i

DESIGN FOR SHEAR (1)

Shear Strength Of Concrete Section

Page 94: Struktur Beton i

DESIGN FOR SHEAR (2)

Shear Strength Of Concrete Section

Perlawanan geser yang terjadi setelah retak miring :1. Perlawanan geser beton yang belum retak, Vcz.2. Gaya ikat (interlock) antara aggregat atau

transfer geser antar permukaan.3. Aksi pasak (dowel action), Vd.4. Aksi pelengkung (arch action), Deep Beam.5. Perlawanan tulangan geser bila ada, Vs.

Page 95: Struktur Beton i

DESIGN FOR SHEAR (3)

Shear Strength Of Concrete SectionTypes of Reinforcement

Page 96: Struktur Beton i

DESIGN FOR SHEAR (4)

Shear Strength Of Concrete Section

Fungsi tulangan geser (Sengkang Begel):1. Memikul sebagian gaya geser, Vs.2. Melawan pertumbuhan geser miring dan ikut

menjaga terpeliharanya lekatan/geseran antar aggregat.

3. Mengikat batang tulangan memanjang untuk tetap diposisinya.

4. Aksi pasak pada beton dan aksi ikatan (confinement) sengkang meningkatkan kekuatan.

Page 97: Struktur Beton i

DESIGN FOR SHEAR (4)

Shear Strength Of Concrete Section

Shear nominal strength (Vn) of concrete section is a combination of shear strength from concrete (Vc) and sehar strength from shear reinforcement (Vs) :

Vn=Vc+VsWhere Vc :

If accurate calculation were used then :

dbfVc wc'6

1

dbfdbbM

dVfV wcw

u

uwcc '' 3.0120

7

1

Page 98: Struktur Beton i

DESIGN FOR SHEAR (5)

Shear Strength Of Concrete Section

Where :

bd

Asw 1

u

u

M

dV

If there is an axial compression load acting in the concrete section therefore Vn can be calculated as follows:

dbfA

NV wc

g

uc '6

1

141

Nu/Ag is in MPa.

Page 99: Struktur Beton i

DESIGN FOR SHEAR (6)

Shear Strength Of Concrete Section

If accurate calculation were used (Axial Compression Load) :

Where :

g

uwcw

m

uwcc A

Ndbfdb

M

dVfV

3.013.0120

7

1''

8

4 dhNMM uum

Page 100: Struktur Beton i

DESIGN FOR SHEAR (7)

Shear Strength Of Concrete Section

If there is an axial tension load acting in the concrete section therefore Vn can be calculated as follows:

Nu/Ag is in MPa.

For circular concrete section area for Vc can be calculated from diameter multiplied by effective width (d=0.8h).

06

13.01 '

dbf

A

NV wc

g

uc

Page 101: Struktur Beton i

DESIGN FOR SHEAR (8)

Shear Strength Of Concrete Section

Minimum shear reinforcement area Avmin :

Minimum shear force acquired from shear reinforcement :

y

wv f

sbA

3min

dbV ws 3

1min

Page 102: Struktur Beton i

DESIGN FOR SHEAR (9)

Design Of Shear Reinforcement

Design of shear reinforcement is divided into several categories, which each category is corresponds with the shear forces acting on the concrete section. This category is divided as below :Condition 1 :

cu VV 5.0Shear reinforcement is not required.Condition 2 :

cc VVuV 5.0Smax < d/2 or Smax < 600 mm, minimum shear reinforcement need to be chekced.

Page 103: Struktur Beton i

DESIGN FOR SHEAR (10)

Design Of Shear Reinforcement

Condition 3 :

Smax < d/2 or Smax < 600 mm, minimum shear reinforcement need to be chekced.Condition 4 :

minscc VVVuV

dbfVVuVV wccsc 'min 3

1

Smax < d/2 or Smax < 600 mm, shear reinforcement need to be calculated as follows :

s

dfAVVVV yv

scusperlu ;

Page 104: Struktur Beton i

DESIGN FOR SHEAR (11)

Design Of Shear Reinforcement

Condition 5 :

Smax < d/4 or Smax < 600 mm, shear reinforcement need to be calculated as follows :

s

dfAVVVV yv

scusperlu ;

dbfVVudbfV wccwcc '' 3

2

3

1

Page 105: Struktur Beton i

DESIGN FOR SHEAR (12)

Design Of Shear Reinforcement

Condition 6 :

Enlarge the concrete cross section.

dbfVVu wcc '3

2

Page 106: Struktur Beton i

DESIGN FOR SHEAR (13)

Design Of Shear Reinforcement (Example 1)

L=6m

Ql=6t/m;Qd=4t/m Spesification :Mutu Beton (f’c)=35 MPaMutu Baja (fy)=400 MpaLebar Balok = 300 mmTinggi Balok = 500 mm

Desain tulangan geser yang diperlukan untuk memikul beban geser yang terjadi.

Ra=Rb=43.2 ton = 423.36 kN

423.36 kN

423.36 kN

Bidang Gaya Lintang

Page 107: Struktur Beton i

DESIGN FOR SHEAR (14)

Design Of Shear Reinforcement

#1 Check All Shear Boundary Condition before calculating the shear reinforcement :Condition 1 :

Condition 2 :

kNdbfVc wc 133450300356

1

6

1'

kNVV cu 9.4913375.05.05.0

kNVukN

VVuV cc

8.999.49

5.0

Page 108: Struktur Beton i

DESIGN FOR SHEAR (15)

Design Of Shear Reinforcement

#1 Check All Shear Boundary Condition before calculating the shear reinforcement :Condition 3 :

Condition 4 :

kNVs 454503003

1min

kNVukN

VVVuV scc

5.1334513375.08.99min

kNVukN

dbfVVuVV wccsc

5.29926613375.05.133

3

1'min

Page 109: Struktur Beton i

DESIGN FOR SHEAR (16)

Design Of Shear Reinforcement

#1 Check All Shear Boundary Condition before calculating the shear reinforcement :Condition 5 :

Condition 6 (Concrete Section Is Satisfied) :

kNVukN

dbfVVudbfV wccwcc

75.49853213375.05.299

3

2

3

1''

kNkN

dbfVVu wcc

75.4986.423

3

2'

Page 110: Struktur Beton i

DESIGN FOR SHEAR (17)

Design Of Shear Reinforcement

#2 Drawing The Shear Boundary Condition :

Vu=423.36 kN

V=498.75kN

IV=299.5kN

III=133kN

II=99.8kN

X1=0.878m

X2=2.057m

X3=2.3m

X4=3m

Page 111: Struktur Beton i

DESIGN FOR SHEAR (18)

Design Of Shear Reinforcement

#3 Calculate each boundary distance :

mX

mQlQd

VuX

mQlQd

VuX

mQlQd

VuX

3

300.28.586.12.392.1

8.9936.423

6.12.1

133

057.28.586.12.392.1

13336.423

6.12.1

133

878.08.586.12.392.1

5.29936.423

6.12.1

5.299

4

3

2

1

Page 112: Struktur Beton i

DESIGN FOR SHEAR (19)

Design Of Shear Reinforcement

#4 Calculate required shear reinforcement in each condition :Condition II :

Use 2 Leg of f10, As = 157 mm2,. Use s = 200 mm.

Since smax < d/2 = 450/2 =225 mm or smax <600mm.Therefore s = 200mm is adequate.

kNdbV ws 453

1min

22min 15750

4003

200300

3mmAvmm

f

sbA

y

wv

kNVkNs

dfAV s

yvs 453.141

200

450400157min

Page 113: Struktur Beton i

DESIGN FOR SHEAR (20)

Design Of Shear Reinforcement

#4 Calculate required shear reinforcement in each condition :Condition III :

Use 2 Leg of f10, As = 157 mm2,. Use s = 200 mm.

Since smax < d/2 = 450/2 =225 mm or smax <600mm.Therefore s = 200mm is adequate.

kNdbV ws 453

1min

22min 15750

4003

200300

3mmAvmm

f

sbA

y

wv

kNVkNs

dfAV s

yvs 453.141

200

450400157min

Page 114: Struktur Beton i

DESIGN FOR SHEAR (21)

Design Of Shear Reinforcement

#4 Calculate required shear reinforcement in each condition :Condition IV :

Therefore in condition IV use s = 100 mm, since smax < d/2 = 450/2 = 225 mm and smax < 600 mm, s =100 mm is adequate.

kNVV

V cusperlu 26.266

75.0

8.995.299

mmV

dfAs

s

yv 10626.266

450400157

Page 115: Struktur Beton i

DESIGN FOR SHEAR (22)

Design Of Shear Reinforcement

#4 Calculate required shear reinforcement in each condition :Condition V :

Therefore in condition IV use s = 50 mm, since smax < d/3 = 450/4 = 112.5 mm and smax < 300 mm, s =50 mm is adequate.

kNVV

V cusperlu 73.431

75.0

8.996.423

mmV

dfAs

s

yv 6573.431

450400157

Page 116: Struktur Beton i

DESIGN FOR SHEAR (23)

Design Of Shear Reinforcement

#5 Drawing the shear reinforcement with the spacing shown below :

3m

0.878m 1.179m

0.943m

S=50mm

S=100mm

S=200mm

Page 117: Struktur Beton i

DESIGN FOR SHEAR (24)

Design Of Shear Reinforcement

#4 Drawing the cross section with longitudinal and shear reinforcement :Condition V

f10-50mm

b=300mm

h=500mm

4D 19

10D 19