Determination of effective length of simply supported beam, hi guys in this article we know about determination of effective length of simply supported beam and what is effective length and what is simply supported beam and how we calculate effective length of simply supported beam.
Effective length of beam shall be define as the smaller of the distance between the centre of bearing support or the clear span between two supports + effective depth of beam.
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As we know beam is load bearing structure member of building and their design should be made according to IS code because of calculation of effective length is quite helpful in their designing.
What is simply supported beam
Beam is load bearing structure if it has two support at their end then it is known as simply supported in other words those beams which are supported by tw support at their end and beam is flexural number of building structure consist of compression and tension bending moment.
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What is effective length of simply supported beam
Effective length of simply supported beam shall be taken as the smaller of the distance between the centre of bearing support or the clear span between two supports + effective depth of beam. Effective span of simply supported beam least of the following which one is smaller value:-
1) clear span + effective depth of beam
2) Centre to Centre distance between two supports
Now taking the short definition of following terms that’s help in understanding the effective length
1) Clear span:– Clear span is distance between inner edge of two supports for beam and it is represented by c.s.
2) effective depth of beam :- effective depth of the beam is the distance from the tension Steel to the edge of compression fibre. In other word it is also described as effective depth of beam is equal to overall depth minus the effective cover of reinforcement.
effective depth = depth _ effective cover
3) effective cover :- is the distance measured from the the outer face of concrete member to the centre of main reinforcement in tension zone or compression zone.
effective cover = Clear cover + half dia of main reinforcement
4) Clear cover :- and clear cover is defined as distance from the outer face of concrete member to the outermost face of reinforcement including shear or torsion stirrup or link.
Clear cover = concrete cover+ dia of stirrup
How to calculate effective length of simply supported beam
Given following diagram we have simply supported beam which is supported by two column at both end and their different values are following
Clear span of beam = 4000 mm inner edge distance
Width of column = 300 mm
Depth of beam = 300 mm
Dia of main reinforcement used in beam = 12mm
Clear cover = 25 mm
Calculation :- value of effective length for simply supported beam is calculated by two factors, and which one have smaller value will be taken as effective length of simply supported beam
1) clear span + effective depth of beam
2) Centre to Centre distance between two supports
1) effective length = clear span + effective depth of beam
We have clear span = 4000 mm
depth of beam = 300 mm
effective depth = depth _ effective cover
efective cover = Clear cover + half dia of main reinforcement
effective cover = 25 mm + Dia/2
effective cover = 25 mm + 12/6 mm
Effective cover = 25+6 =31 mm putting this value
effective depth = 300 mm _31 = 271 mm
effective length of beam = 4000 + 271 mm
effective length of beam = 4271 mm
Now do another calculation
2) effective length of beam is equal to Centre to Centre distance between two supports
C–C distance = clear span + half of width of two column
Effective length = 4000 + w/2 +w/2
Width of column = 300 mm put this value
Effective length = 4000 +300/2 +300/2
Effective length = 4300 mm
1) in case first effective length of simply supported beam is coming 4271 mm
2) in case second effective length of simply supported beam is coming 4300 mm
You have to choose smaller values between two cases and smaller value is 4271 mm. So 4271 mm is effective length of simply supported beam.