Design of rectangular & t beam using usd

DESIGN OF RECTANGULAR & T-BEAM USING USD

SUBMITED BY- MD.TIPU SULTAN 121116

SUBMITED TO Dr. Md. Rejaul Karim(Ph.D)

DEPARTMENT OF CIVIL ENGINEERING DUET

contents

Definition of T-Beam: slide 4Effective flange width of T-Beam: slide 6Strength Analysis: slide 9Design of T-Beam: slide 12

DESIGN OF RECTANGULAR Beam

Definition of Beam:

Beam is the horizontal member of a structure, carrying transverse load. Beam carry the Floor slab or the roof slab. Bram transfer all the loads including its self-weight to the columns or walls.

Definition of R.C.C Beam:

R.C.CDue . Beam is to bendingtical moments and shear. to the versubjected external load , bending compresses the top fibers of the beam and elongates the bottom fibers. The strength of R.C.C. beam depends on the compsite action of concrete and steels

Rectangular beam design : singly & doubly reinforced beam by USD

• Compressive Strength of Concrete, f‘c (3000-5000psi)• Yield Strength of Steel, fy(40-60 grade)• Spacing of Reinforcement------ (≥ maximum diameter of the

bars or 1-1.5in or 1.50 times maximum size of aggregate) • Concrete Cover------ ( for main bars 1in and stirrups 0.75 in)• Beam Width• Beam Depth, d• Steel Area

Physical Factors

Strength Factors

Important Considerations In Design

•Factored Loads (Generally 1.2 Dead Load + 1.6 Live Load which implies factored moment Mu)•Capacity Reduction Factors,

ɸ = 0.9 for Bending in Reinforced Beam; = 0.75 for Shear and Tension.

Important DefinitionsBalanced Steel Ratio

When due to same load tensile steel theoretically reach its yield and concrete attains its ultimate strain 0.003.

ρb = 0.85 * (f’c/fy) * [{0.003/0.003+(fy/Ey)}*d].Under Reinforced Beam

When steel begin to yield even though concrete compressive strain < 0.003.

Steel ratio <<<< ρb. Failure with warning

Over Reinforced Beam When steel begin to yield with concrete compressive failure. Steel ratio >>>> ρb. Sudden Failure.

Design Types of RCC Beams

Singly Reinforced Beam Steel Only at Tension Zone i.e. below neutral zone. Design procedure is General Flexural Design. Generally Rectangular Beam. Design as when ɸMn ≥ Mu

Doubly Reinforced BeamSteel in Compression as well as Tension Zone.

General Flexural Design both for top and bottom fibre.

Both Rectangular and T-beam.

Design as when ɸMn ≤ Mu.

Flexural Design EquationsSingly Reinforced Beam

Steel calculation Client already deliver

design &demand.

Country code give to you load for this demand.Such as BNBC/ACI.

Moment calculation

For S.S.B M/8If Beam size consider by Architect &Compression zone not perfectTo carry compression load you should be Design doubly Reinforced Beam,

DESIGN OF T- Beam

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T BEAM DESIGN : SINGLY & DOUBLY : USD

Definition of T-Beam:

When slabs are monolithically casted with beams in a positive moment zone, part of the slab act as a part of the beam and resist the longitudinal compression. The resulting section is T beam.

The top of the T-shaped cross section serves as a flange or compression member in resisting compressive stresses.

Fig:T-Beam

Effective flange width of T-Beam:

Strength Analysis:

For case I:Area of concrete section, Area of steel are known a Calculation

Are of concrete section, Area of steel are known

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εc=0.003

d

c

0.85fc’a/2

d-a/2

C

T

Strain Diagram Stress Diagram

As

hf

n n1 n2

n1 s sf y

fn2 sf y

2

2

M M M

aM A A f d

hM A f d

For : fha

b

bw

And Nominal moment capacity will be Mn = Mn1+ Mn2

T- Beam Moment calculation

Design of T-Beam:

Moment or

loading is given

Area of steel in flange

Nominal moment

Moment For Web

Area of steel (Web)

Total area of steel

conclusion