Effective span of beam for simply supported, Cantilever, Continous- IS

The effective span of beam is different for different types of the beam. It depends upon the clear span as well as the depth of the beam.

The Span of different beam are given below. But, first of all you should know about,

What is Clear Span?

The span of the beam without measuring the length of support is known as Clear span of the beam.

What is effective Span?

It is measured according to IS code 456-2000.

What is effective cover?

It is distance between the outer surface of beam and the middle of the main steel rod provided in the beam.

What is effective depth?

It is the (Total depth of beam – effective cover of beam). You can see in picture below.

Effective span for Simply supported beam

The effective span of a simply supported beam is taken as the least of the following:

Clear span + the effective depth of beam.

Center to center ( c/c ) distance between supports.

For Continuous beam

In case of continuous beam, if the width of the support is less than 1/12 of the clear span, the effective span is taken as in (a).

If the width of support is more than 1/12 of the clear span or 600 mm whichever is less, the effective span is taken as:

For end span with one end fixed and the other continuous or for intermediate spans, the effective span is taken as the clear span between supports;

For end span with one end free and the other continuous, the effective span is equal to the clear span + half the effective depth of the beam or the clear span + half the width of the discontinuous supports, whichever is less.

In case of span with roller or rocket bearings, the effective span always the distance between the centre of bearing.

Cantilever beam

The effective length of a cantilever beam is taken as its length to the face of the supports + half the effective  depth except where it forms the end of a continuous beam.

I hope you got something new.

Happy Learning – Civil Concept

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