DOUBLY REINFORCED BEAM

By:-

ISHAN GARG

120695030

B.Arch. , 5th Sem.

Having steel in compression and tension zones

Used in such situations

the ultimate moment of resistance required is

greater than the ultimate moment of resistance of

the singly reinforced balanced section

when depth of the beam is constraints

Beam will be found necessary when the depth of the

beam is restricted

Also to serve functional or aesthetic requirements.

Reinforcing on the tension side not enough to resist the

bending moment.

As increase in quantity of steel on tension side,

moment of resistance get increased indefinitely.

However, the total tension reinforcement cannot

exceed the maximum permissible tension

reinforcement.

Live loads may alternate could occur on both face of

member.

Loading may be eccentric,

Also eccentricity of the load may change from one

side of the axis to another side.

The member may be subjected to dynamic loading

(eg.:-vibrations or impact or accidental lateral thrust)

Assumption Compression is resisted only by compression steel.

Tension is resisted by tension steel.

Stress in compression steel = Stress in tension steel

Concrete serves only as a web of an I

Determining the amount of moment of resistanceknowing breadth, depth, area of tension andcompression steels and their covers.

Design involves the determination of cross-sectionaldimensions, area of tension and compressionreinforcements

First step

to determine whether compression steel is required.

done by comparing the factored bending momentwith the limiting moment of resistance of a singlyreinforced section