L- beams or flanged beams

this is the presentation on L-beams made bi jagmeet singh sidhu, student of gndec ludhiana.

1. PROJECT REPORT
ON
L-BEAMS
Submitted By:-
Jagmeet Singh Sidhu
D3Ce,6040.
Submitted To:-
Dr.HS Rai
HOD Civil Depertment

2. L - Beams
The end beams which have slabs on one side only,acts as L-beams.
In most of the reinforced concrete structures,concrete slabs are cast
monolithic. In a floor consisting of several beams cast monolithically with
the slab,the intermediate beams act as T-beams whereas the beams at
top of the corners of the walls or beams around the staircase or lift
openings are called L-beams.Thus,T-beams and L-beams forms a part
of the floor system together with slab. L-beams are typical floor beams
because of the reduced overall structural depth,the beams are in
prestressed or reinforced concrete.

3. Analysis of Flanged SectionAnalysis of Flanged Section
Slab acts as a top
flange to the beam. T-
beams and Inverted L
Beams are shown.

4. Type of stress in L-beams:-

In bending the beams take tension forces and slabs takes
compression forces. Since the L-beams receive their loads from one side
only,they are subjected to considerable amount of torsional
moments.So L-beams are subjected to bending moment,shear force
and torsional moment.

5. Combination of T and L-beams

6. Moment carried by flange of L-beams.
The moment M1 causes
torsion in the beam and is
known as the torsion
moment which is restricted
by the rectangular portion
only and the flange does
not contribute to torsional
moment of resistance.

7. The central load W
causes bending
moment in the beam
which is joined
restricted by the
rectangular portion
of the beam as well
as the flange.
Moment carried by flange of L-beams and
the slab.

8. Changes in floor level may be accommodated by either an L-
beam or by building up one side of an inverted T-beam, as
shown in the figure.

9. Code recommends that effective width of the
flange of beams may be taken as follows:-
1. For L-beams,lesser of:-
[a] bf = lo/12 + bw + 3Df
[b] bf = X1 + bw
2. For Isolated L-beams,lessor of:-
[a] bf = 0.5lo/(lo+b)+4 + bw
[b] bf = b
Where,bf = effective width of flange
bw = breath of rib or web
b = actual width of flange
lo = distance between points of zero moment in abeam.
X1 and X2 = half of clear distance between two adjacent beams.

10. The design principles to be followed
while designing L-beam.
Given:-
1. Type of mix
2. Thickness of slab
3. Bending and shear force
Step-1:- Determine width of flange bf.
Step-2:- Fix up a suitable depth arbitery.
Step-3:- Calculate moment of resistance of the section assuming
the failure of concrete to occur.If the moment of resistance
is greater than bending moment assumed depth is
ok,otherwise either increase the depth of the section or
provide additional reinforcement in compression side in
addition to the tension side.

11. Step 4:- Calculate the amount of tension steel for actual bending
moment treating it as a balanced section.
Step 5:- Check for the shear and provide shear reinforcement.
Step 6:- Check of Deflection.
Step 7:- Check for end anchoring and development length.

12. THANK YOU.