How to calculate the effective span of the RCC continuous beam? (Part-3) / Calculating the effective length of a continuous beam as per IS-456.

 

 Part -2  👈 Back      

Example -4:

Let us calculate the effective span of the continuous beam as shown below.

Given data:

Clearspan of the beam = 4500mm.=4.5m.

Width of the column support=450mm.

Beam depth = 450mm.

Beam width =230mm.

Clear cover = 25mm.

Dia. of stirrup bar = 8mm.

Dia. of bottom bar = 20mm.

Calculation:

Let us check condition-1 of the IS-456 code.

         [1/12 × clear span] 

        = [1/12 ×4500mm.]

        = 375mm. < 450mm.

Here, the width of the column support is more than 1/12th of the clear span of the beam.

According to IS-456:2000, the effective span (length) of a continuous beam is defined as given below.

                              

The given continuous beam has one free end & the other continuous.

So, as per IS-456,

Step-1:

The effective span of the beam

= [clear span of the beam + 1/2 ×  effective depth]

= [4500mm. + 1/2 × 407mm.]

= [4500mm.+ 203.5mm.]

= 4703.5mm.

Step-2:

The effective span of the beam

= [clear span of the beam + 1/2 × width of support]

= [4500mm. + 1/2 × 450mm.]

= [4500mm. + 225mm.]

= 4725mm.

Note: The effective depth (taken above) is calculated in the separate article as linked below.

Go through the article 👇

👀.  How to calculate the effective cover & effective depth of a simply supported beam?

Step-3

The actual effective span of the beam will be the lesser of the values calculated in step-1 & step-2

Here,  step-1 < step-2

i.e. 4703.5mm.< 4725mm.

So, the effective span of the beam = 4703.5mm.

Note: Go through all the 3 parts to understand the effective span wholistically.

👀  To go through all types of construction-related procedures & checklists, click here.

Thank you for going through this article❤. Have a good day 😄.

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