t beam usd
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AHSANULLAH UNIVERSITY OF SCIENCE & TECHNOLOGY
DEPARTMENT OF CIVIL ENGINEERING
CE-416PRE-STRESSED CONCRETE LAB
SESSIONAL
PRESENTED BY:S. M. RAHAT RAHMAN
ID NO:10.01.03.044
COURSE TEACHERS:MUNSHI GALIB MUKTADIR
SABREENA NASRIN
T BEAM DESIGN : SINGLY & DOUBLY : USD
USD (ULTIMATE STRENGTH DESIGN METHOD)
T-BEAM
T - BEAM ACTS LIKE SINGLY REINFORCED BEAM
T – ACTION VS RECTANGULAR ACTION
EFFECTIVE FLANGE WIDTH OF T-BEAM
STRENGTH ANALYSIS
NOMINAL MOMENT FOR T SECTION
CONTENTS
ULTIMATE STRENGTH DESIGN(USD)
Assuming tensile failure condition
Additional strength of steel after yielding
ACI code emphasizes this method.
T-BEAM
Concrete beams are often casted integrally with the slab and formed a “T” – shaped beam.
These beams are very efficient .
Here slab portion carries the compressive load and web portion carries the tension .
T-BEAM
Occurrence and Configuration of T-Beams• Common construction type• The slab forms the beam flange, while the part of the beam projecting below the slab forms is what is called web or stem.
SINGLY REINFORCED BEAM
Tension Zone
Compression Zone
Figure : Singly Reinforced Beam for positive moment condition
DOUBLY REINFORCED BEAM
Figure : Doubly Reinforced Beam for positive moment condition
Compression Zone
Tension Zone
T BEAM BEHAVES AS SINGLY REINFORCED BEAM
CONTINUOUS T-BEAM
T-Action
Rectangular
CONTINUOUS T-BEAM
T Versus Rectangular Sections
When T-shaped sections are subjected to negative bending moments, the flange is located in the tension zone. Since concrete strength in tension is usually neglected in strength design, the sections are treated as rectangular sections.
On the other hand, when sections are subjected to positive bending moments, the flange is located in the compression zone and the section is treated as a T-section.
EFFECTIVE FLANGE WIDTHFrom ACI 318, Section 8.10.2
Effective Flange Width : Condition 1
For symmetrical T-Beam or having slab on both sides
a) 16 hf + bw
b) Span/4 c) c/c distance
EFFECTIVE FLANGE WIDTHFrom ACI 318, Section 8.10.2
Effective Flange Width : Condition 2 Beams having slabs on one side only
a) bw + span/12 b) bw + 6hf
c) bw + 1/2 * beam clear distance
EFFECTIVE FLANGE WIDTHFrom ACI 318, Section 8.10.2
Effective Flange Width :Condition 3
Isolated T Beam
a) beff ≤ 4 bw
b) hf ≥ bw/2
T - SECTION (STRENGTH ANALYSIS)
Strength Analysis :
1st case : (N.A. is with in the flange)
Analyseas a rectangular beam of width
=
T-SECTION (STRENGTH ANALYSIS)
Case 1 : (N. A. is with in Flange)
hf
Strain Diagram Stress Diagram
T-SECTION (STRENGTH ANALYSIS)
Case 2 : (N. A. is with in Web)
ANALYSIS OF T-BEAM
18
Analysis of T-Beams - ( a > hf)
Consider the total section in two parts:
1) Flange overhangs and corresponding steel;2) Stem and corresponding steel;
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
T BEAM MOMENT CALCULATION
For : fha
T BEAM MOMENT CALCULATION
Part-1
0.85 fc’ bw a = As1 fy
Part-2
0.85 fc’ (b-bw) hf = As2 fy
0.85 fc’ bw a + 0.85 fc’ (b-bw) hf = As fy
Where,
As1 = As – Asf
As2 = Asf
Thank you
ANY QUESTION ?
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