FLITCHED BEAMS

GUIDED BY-Prof- PRIYANKA CHATORAJ

PRESENTED BY-GROUP- 2

OVERVIEW

WHAT IS A BEAM?

TYPES OF BEAMS

WHAT IS A COMPOSITE BEAM?

TYPES OF COMPOSITE BEAMS

WHAT IS A FLITCHED BEAM?

DESIGN PRINCIPLE OF A FLITCHED BEAM

APPLICATIONS & ADVANTAGES

LIMITATIONS & DRAWBACKS

WHAT IS A BEAM?

• A beam is a structural element that is capable of withstanding load primarily by

resisting against bending.

• The bending force induced into the material of the beam as a result of the

external loads, own weight, span and external reactions to these loads is called

a bending moment.

• Beams are characterized by their profile (shape of cross-section), their length, and

their material.

TYPES OF BEAMS

Beams are characterized by their profile (shape of cross-section), their geometry,

equilibrium condition, by their supports and their material.

According to end support:

• Simply Supported beam

• Continuous Beams

• Overhanging Beam

• Cantilever Beam

• Fixed BeamOverhanging beam

Simply supported beam Continuous beam

According to cross section:A beam may have different cross section. The most common cross section of beam are as follow.• I Beam• T Beam• C beam

According to Geometry:• Straight beam• Curved beam• Tapper beam

According to equilibrium:• Statistically determinate beam• Statistically indeterminate beam

According to material:• Timber beam• Steel beam• Concrete beam

WHAT IS COMPOSITE BEAM ?

• A structural member composed of two or more dissimilar materials joined

together to act as a unit in which the resulting system is stronger than the

sum of its parts.

• There are two main benefits of composite action in structural members

first, by rigidly joining the two parts together , the resulting system is

stronger than the sum of its parts. Second, composite action can better

use the properties of each constituent material

TYPES OF COMPOSITE BEAMS

1. BEAMS OF UNSYMMETRICAL STRUCTURES

2. BEAMS OF UNIFORM STRENGHT

3. FLITCHED BEAMS

WHAT IS A FLITCHED BEAM ?

• A flitch beam (or flitched beam) is a compound beam used in the construction of

houses, decks, and other primarily wood-frame structures.

• Typically, the flitch beam is made up of a steel plate sandwiched between two

wood beams, the three layers being held together with bolts.

• In that common form it is sometimes referenced as a steel flitch beam.

• Further alternating layers of wood and steel can be used to produce an even

stronger beam.

TYPES OF FLITCHED BEAMS

THEORY OF COMPOSITE SECTION

Consider a beam of composite section made up of two different materials say

( timber and steel)

Where they behave like a single piece and on application of load they bend to

same radius of curvature

In such cases the total moment of resistance will be equal to the sum of

moments of individual sections

12

E1- Modulus of elasticity of part1

I1-Moment of inertia of part1

M1-Moment of resistance for part1

S1- Stress in part1

Z1-Modulus of section for part1

Similarly, E2, I2, M2, S2 and Z2 are corresponding values of part2

We know that the moment of resistance for beam1:

M1 = S1 × Z1M2 = S2 × Z2

Therefore total momentum of resistance of composite sections

M = M1 + M2 = (S1 × Z1) + (S2 × Z2)

From the above to relations it is evident that a flitched beam is more efficient tocarry good load with high resistance to Bending Moment.

We also know that any distance from neutral axis, strain in both materials issame

S1/E1 = S2/E2

APPLICATIONS & ADVANTAGES

• Flitch beams are significantly stronger than wood alone.

• They require less depth than a wood-only beam of the same

strength

• They are much lighter than a steel beam of the same size.

• They can still be nailed to the rest of a wooden structure.

• Flitch beams can also be created from existing in-situ joists or

beams permitting easier renovations.

LIMITATONS & DRAWBACKS

• Due to the high cost of labour, use of this type of beam has greatly

declined.

• The advent of high-strength engineered lumber which uses modern

adhesives and lower cost wood fibres has rendered this system largely

obsolete.

• Engineered lumber is cut to length and installed similar to sawn lumber.

• The flitch requires shop fabrication and/or field bolting.

• This coupled with a much increased self weight of the beam (11.4

pounds (5.2 kg) for engineered wood vs. 25.2 pounds (11.4 kg) for a

flitch beam) decreases the viability of the system

THANK YOU