L- beams or flanged beams

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

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.

Analysis of Flanged Section ,[object Object]

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.

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.

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.

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.

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.

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.

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.

L- beams or flanged beams

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