CLass notes (partial)

1. BEAMS
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2. 1. Bond stress is stress acting parallel to the
bar on the interface between the
reinforcing bar and the surrounding
concrete. It resists any force which tries to
pull out from the concrete.
2. Anchorage bond : to transfer force from bar
to surrounding concrete before it is
terminated.
3. The length of the bar required to transfer
the force in the bar to surrounding concrete
concrete through bond is called
development length
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3. Cracks in beam
•The combination of shear and bending stresses produces the principle stress which
causes diagonal tension in beam section.
•Flexural cracks occur at points of maximum bending moment ,when the cross section
is insufficient or main reinforcement is not sufficient.
•Crushing of concrete occurs when concrete is disturbed at early stage .
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4. DESIGN OF SHEAR REINFORCEMENT
•Shear reinforcement has to be provided against
diagonal tensile stresses caused by the shear force.
•The longitudinal bars do not provide the failure.
•The inclined shear crack starts at the bottom near the
support and extends towards compression zone. The
shear reinforcement can be any of the following
1. Vertical stirrups.
2. Bent up bars along with stirrups
3. Inclined stirrups.
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6. General arrangement of the vertical stirrups is shown in the fig below:
• The stirrups are placed around the tensile reinforcement and taken to the
compression zone and anchored the hanger bars.
• Hanger bars are provided to keep the stirrups in position otherwise they may
be displaced.
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7. Some of the longitudinal bars can be bent near the supports as bending
moment to be resisted near the supports is very little. Such bent bars
reduce diagonal tension.(73,85)
Doubly reinforced beam -96
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11. Type of
Hook/Bend
U-Hook 45 degree
bend
90 degree
bend
135 degree
bend
180 degree
bend and
more
Anchorage value 16d 4d 8d 12d 16d
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12. Reinforcement detailing
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13. CURTAILMENT OF TENSION REINFORCEMENT
Tension reinforcement is designed for sections where B.M. is
maximum. For economy, it is general practice to curtail the bars
where B.M. is less.
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15. • Slabs are plane structural members whose
thickness is small compared to its length and
breadth.
• Slabs are used as roof covering and floors
• Beams or walls are common supports for them
• Slabs supports mainly transverse loads.
• When slab occurs on both sides of a
beam(intermediate beams) , the beam is known
as T beam
• When the Slab is only on one side of the
beam(end beams), the beam is known as L
Beam
• The total resulting section (slab and beam ) is
known as flanged section.
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16. Dimensions of T beam(37)
1. Monolithic T-Beams: A such type of beam which constructed by moulding a
rectangular beam and slab together. It looks like a rectangular beam supporting slab.
2. Isolated T-Beams: An Isolated T-Beam is such type of beam in which flange of T- Beam
not connected with the slab.
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17. MOMENT OF RESISTANCE OF T SECTIONS
CASE 1( 96- G-2.1)
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18. CASE 2( 96- G-2.2)
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19. CASE 2( 96,97- G-2.2.1)
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